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1
Costa, Marcus Vinicius de Lima, Pedro Antônio de Lima Félis, Kelvin Jean Santos Masselani, Túlio Lopes Marinho Linard, Luis Alberto Bucci, and Willyam de Lima Vieira. "Organization of leaf vascular system and gas exchange in seedlings of Guazuma ulmifolia Lam. in different light conditions." Scientific Electronic Archives 14, no. 7 (July 1, 2021): 68–73. http://dx.doi.org/10.36560/14720211366.
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In tropical forests, different physiological characteristics of leaves in tree species are evidenced by variations in different incident light conditions. We aim to evaluate gas exchange and organization of leaf vascular system in Guazuma ulmifolia Lam. seedlings under different light conditions. Seedlings were obtained from seeds germinated under greenhouse conditions with controlled environment. Ninety days after germination, seedlings in 8kg pots were transferred to the experimental site to allow acclimatization under sun and shade conditions. The experimental design was completely randomized, with two treatments: full sunlight and artificial shading, limiting the luminosity to about 5% of irradiance. Seedlings were maintained under these conditions for 120 days before measuring gas exchange parameters. We measured photosynthetic rate, stomatal conductance, sub-stomatic CO2 concentration, transpiration, and chlorophyll content. Anatomical analysis measured distance between veins, distance from veins to abaxial epidermis, distance from veins to adaxial epidermis, distance from veins to stomata, total leaf thickness, abaxial epidermis thickness, adaxial epidermis thickness, palisade parenchyma thickness, and spongy parenchyma thickness of foliar gas exchange of G. ulmifolia which presented significant differences between light environments. Photosynthetic rate and stomatal conductance were reduced by 78% and 39%, respectively, in shade, while stomatal conductance increased by 31% in full sunlight. Transpiration showed no significant difference between the two treatments, but chlorophyll content was 30% lower in full sunlight. Distance between veins and distance from veins to stomata showed no difference between treatments, but the other parameters increased in full sunlight. Thus, the results showed that the pioneer species G. ulmifolia presented leaf gas exchange acclimated to environments with high luminosity.
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Zoulias, Nicholas, Emily L. Harrison, Stuart A. Casson, and Julie E. Gray. "Molecular control of stomatal development." Biochemical Journal 475, no. 2 (January 31, 2018): 441–54. http://dx.doi.org/10.1042/bcj20170413.
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Plants have evolved developmental plasticity which allows the up- or down-regulation of photosynthetic and water loss capacities as new leaves emerge. This developmental plasticity enables plants to maximise fitness and to survive under differing environments. Stomata play a pivotal role in this adaptive process. These microscopic pores in the epidermis of leaves control gas exchange between the plant and its surrounding environment. Stomatal development involves regulated cell fate decisions that ensure optimal stomatal density and spacing, enabling efficient gas exchange. The cellular patterning process is regulated by a complex signalling pathway involving extracellular ligand–receptor interactions, which, in turn, modulate the activity of three master transcription factors essential for the formation of stomata. Here, we review the current understanding of the biochemical interactions between the epidermal patterning factor ligands and the ERECTA family of leucine-rich repeat receptor kinases. We discuss how this leads to activation of a kinase cascade, regulation of the bHLH transcription factor SPEECHLESS and its relatives, and ultimately alters stomatal production.
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Zhu, Jiali, Ji-Hwan Park, Seulbee Lee, Jae Ho Lee, Daehee Hwang, June M. Kwak, and Yun Ju Kim. "Regulation of stomatal development by stomatal lineage miRNAs." Proceedings of the National Academy of Sciences 117, no. 11 (March 2, 2020): 6237–45. http://dx.doi.org/10.1073/pnas.1919722117.
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Stomata in the plant epidermis play a critical role in growth and survival by controlling gas exchange, transpiration, and immunity to pathogens. Plants modulate stomatal cell fate and patterning through key transcriptional factors and signaling pathways. MicroRNAs (miRNAs) are known to contribute to developmental plasticity in multicellular organisms; however, no miRNAs appear to target the known regulators of stomatal development. It remains unclear as to whether miRNAs are involved in stomatal development. Here, we report highly dynamic, developmentally stage-specific miRNA expression profiles from stomatal lineage cells. We demonstrate that stomatal lineage miRNAs positively and negatively regulate stomatal formation and patterning to avoid clustered stomata. Target prediction of stomatal lineage miRNAs implicates potential cellular processes in stomatal development. We show that miR399-mediatedPHO2regulation, involved in phosphate homeostasis, contributes to the control of stomatal development. Our study demonstrates that miRNAs constitute a critical component in the regulatory mechanisms controlling stomatal development.
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Flore, James A., and Lynn Sage. "Using Video Thermal Image Analysis to Monitor Stomatal Opening in Fruit Crops." HortScience 31, no. 4 (August 1996): 578e—579. http://dx.doi.org/10.21273/hortsci.31.4.578e.
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This study demonstrates that thermal image analysis can be used to localize stomatal opening and closing on leaves of apple, and cherry. An attached leaf was placed in an environmental chamber used for gas exchange and leaf temperature was monitored with cromel-constantan thermocouples, (0.08 mm) pressed against the underside of the leaf, or with an Inframetrics 600 thermal image analyzer that was focused on the upper side of the leaf. Radiation was monitored in the 8–12 μm range and the image was recorded on video tape. A two-degree temperature difference due to stomatal opening was detected. Stomatal opening as monitored by gas exchange was correlated significantly with leaf temperature. Under steady state conditions, stomata from cherry oscillated at 20-minute intervals. Stomata opened and closed uniformly. Factors investigated were light, carbon dioxide, ABA, and water stress. In all cases changes in temperature correlated with stomatal opening and closing. Response time to a change in environment was less than 10 minutes. The practical implications of this study are discussed.
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Klejchová, Martina, Adrian Hills, and Michael R. Blatt. "Predicting the unexpected in stomatal gas exchange: not just an open-and-shut case." Biochemical Society Transactions 48, no. 3 (May 26, 2020): 881–89. http://dx.doi.org/10.1042/bst20190632.
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Plant membrane transport, like transport across all eukaryotic membranes, is highly non-linear and leads to interactions with characteristics so complex that they defy intuitive understanding. The physiological behaviour of stomatal guard cells is a case in point in which, for example, mutations expected to influence stomatal closing have profound effects on stomatal opening and manipulating transport across the vacuolar membrane affects the plasma membrane. Quantitative mathematical modelling is an essential tool in these circumstances, both to integrate the knowledge of each transport process and to understand the consequences of their manipulation in vivo. Here, we outline the OnGuard modelling environment and its use as a guide to predicting the emergent properties arising from the interactions between non-linear transport processes. We summarise some of the recent insights arising from OnGuard, demonstrate its utility in interpreting stomatal behaviour, and suggest ways in which the OnGuard environment may facilitate ‘reverse-engineering’ of stomata to improve water use efficiency and carbon assimilation.
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Higgins, Stewart S., R. Alan Black, Gary K. Radamaker, and William R. Bidlake. "Gas exchange characteristics and water relations of Larixoccidentalis." Canadian Journal of Forest Research 17, no. 11 (November 1, 1987): 1364–70. http://dx.doi.org/10.1139/x87-211.
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Photosynthetic, transpirational, and stomatal responses to light, temperature, humidity, and plant moisture stress were measured for greenhouse-grown seedlings of Larixoccidentalis Nutt. Light saturation was 550 μmol photons•m−2•s−1; light and CO2 compensation points were 26 μmol photons•m−2•s−1 and 59 μL CO2•L−1, respectively. Light-saturated photosynthetic rate was over 7 μmol CO2•m−2•s−1 with a temperature optimum between 18 and 23 °C. Photosynthesis, transpiration, and stomatal conductance to water vapor declined as xylem pressure potential decreased from −1.5 to less than −2.5 MPa; above −1.5 MPa no effect was observed. Stomatal conductance declined with increasing leaf to air vapor density difference. Stomatal conductance increased with increasing irradiance. Nighttime stomatal conductance was about 50% of the daytime maximum conductance regardless of xylem pressure potential. When plants were well watered, the ratio of xylem pressure potential to transpiration (XPP/E) decreased by 1.5 × 10−3 MPa•(μg H2O•cm−2•s−1)−1 with each mg H2O•cm−2 that had been transpired. After 7 days of drought, however, XPP/E decreased at 7.9 × 10−3 MPa•(μg H2O•cm−2•s−1)−1 per mg H2O•cm−2. These characteristics are compared with other conifers and are used to suggest differences between growth patterns of L. occidentalis and sympatric species.
7
Paoletti, Elena, Nancy E. Grulke, and Rainer Matyssek. "Ozone Amplifies Water Loss from Mature Trees in the Short Term But Decreases It in the Long Term." Forests 11, no. 1 (December 31, 2019): 46. http://dx.doi.org/10.3390/f11010046.
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We measured whole-tree transpiration of mature Fagus sylvatica and Picea abies trees exposed to ambient and twice-ambient O3 regimes (1xO3 and 2xO3 free-air fumigation). After eight years, mean daily total transpiration did not vary with the O3 regime over the 31 days of our study, even though individual daily values increased with increasing daily O3 peaks in both species. Although the environmental parameters were similar at 1xO3 and 2xO3, the main factors affecting daily transpiration were vapour pressure deficit in 2xO3 spruce and O3 peaks in beech. For a mechanistic explanation, we measured O3-induced sluggish stomatal responses to variable light (sunflecks) by means of leaf-level gas exchange measurements only in the species where O3 was a significant factor for transpiration, i.e., beech. Stomata were always slower in closing than in opening. The 2xO3 stomata were slower in opening and mostly in closing than 1xO3 stomata, so that O3 uptake and water loss were amplified before a steady state was reached. Such delay in the stomatal reaction suggests caution when assessing stomatal conductance under O3 pollution, because recording gas exchange at the time photosynthesis reached an equilibrium resulted in a significant overestimation of stomatal conductance when stomata were closing (ab. 90% at 1xO3 and 250% at 2xO3). Sun and shade leaves showed similar sluggish responses, thus suggesting that sluggishness may occur within the entire crown. The fact that total transpiration was similar at 1xO3 and 2xO3, however, suggests that the higher water loss due to stomatal sluggishness was offset by lower steady-state stomatal conductance at 2xO3. In conclusion, O3 exposure amplified short-term water loss from mature beech trees by slowing stomatal dynamics, while decreased long-term water loss because of lower steady-state stomatal conductance. Over the short term of this experiment, the two responses offset each other and no effect on total transpiration was observed.
8
Sawinski, Katja, Sophia Mersmann, Silke Robatzek, and Maik Böhmer. "Guarding the Green: Pathways to Stomatal Immunity." Molecular Plant-Microbe Interactions® 26, no. 6 (June 2013): 626–32. http://dx.doi.org/10.1094/mpmi-12-12-0288-cr.
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Guard cells regulate plant gas exchange and transpiration by modulation of stomatal aperture upon integrating external cues like photosynthetic effective illumination, CO2 levels and water availability and internal signals like abscisic acid (ABA). Being pores, stomata constitute a natural entry site for potentially harmful microbes. To prevent microbial invasion, stomata close upon perception of microbe-associated molecular patterns (MAMPs), and this represents an important layer of active immunity at the preinvasive level. The signaling pathways leading to stomatal closure triggered by biotic and abiotic stresses employ several common components, such as reactive oxygen species, calcium, kinases, and hormones, suggesting considerable intersection between MAMP- and ABA-induced stomatal closures, which we will discuss in this review.
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Montague, Thayne, Roger Kjelgren, and Larry Rupp. "Gas Exchange and Growth of Two Transplanted, Field-grown Tree Species in an Arid Climate." HortScience 35, no. 4 (July 2000): 763–68. http://dx.doi.org/10.21273/hortsci.35.4.763.
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Gas exchange and growth of transplanted and nontransplanted, field-grown Norway maple (Acer platanoides L. `Schwedleri') and littleleaf linden (Tilia cordata Mill. `Greenspire') trees were investigated in an arid climate. In the spring of 1995, three trees of each species were moved with a tree spade to a new location within a field nursery and three nontransplanted trees were selected as controls. Predawn leaf water potential, morning-to-evening stomatal conductance and leaf temperature, leaf-to-air vapor pressure difference, midday stomatal conductance and photosynthetic rate, and growth data were collected over a 2-year period. After transplanting, weekly predawn leaf water potential indicated that transplanted trees were under greater water stress than were nontransplanted (control) trees. However, predawn leaf water potential of maple trees recovered to control levels 18 weeks after transplanting, while that of transplanted linden trees remained more negative than that of controls. In 1995, stomatal conductance and photosynthetic rates were lower throughout the day for transplanted trees. In 1996, gas exchange rates of transplanted maple trees recovered to near control levels while rates for transplanted linden trees did not. Sensitivity of stomata to leaf-to-air vapor pressure difference varied with species and with transplant treatment. Each year transplanted trees of both species had less apical growth than did control trees. Although gas exchange and apical growth of transplanted trees was reduced following transplanting, recovery of gas exchange to control rates differed with species.
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Idris, Aisha, Alona C. Linatoc, Aisha M. Aliyu, Surayya M. Muhammad, and Mohd Fadzelly Bin Abu Bakar. "Effect of Light on the Photosynthesis, Pigment Content and Stomatal Density of Sun and Shade Leaves of Vernonia Amygdalina." International Journal of Engineering & Technology 7, no. 4.30 (November 30, 2018): 209. http://dx.doi.org/10.14419/ijet.v7i4.30.22122.
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Light affects the growth and development of plants by influencing the physical appearance of one leaf as well as the appearance of the whole plant. Plant photosynthesis, stomata density, and pigment contents are all influenced by light The objective of this research is to determine the effect of light on the photosynthesis, pigment content and stomatal density of Sun and Shade Leaves of Vernonia amygdalina. Gas exchange was measured using Li-6400 and the data obtained was used to create a light response curve where parameters including light saturation point (LSP), light compensation point (LCP) and apparent quantum yield were estimated. Photosynthetic pigment were quantified spectrophotometrically. Moreover, the stomatal density was counted under light microscope, after making a nail polish impression of the leaf. The results discovered shows that as the light intensity increases, the gas exchange and stomatal density increases while the photosynthetic pigment of the studied plant decreases (P<0.05). In addition, LSP and LCP increases with increasing light intensity. Besides, statistically significant negative correlation (P<0.05) was achieved among stomatal density and transpiration rate thereby leading to a conclusion that sun leaves of Vernonia amygdalina contribute the highest assimilation rate to the plant than shade leaves. Yet, the higher stomatal density of sun leaves provides water saving to the plant.
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Henson, IE, CR Jensen, and NC Turner. "Leaf Gas Exchange and Water Relations of Lupins and Wheat. III. Abscisic Acid and Drought-Induced Stomatal Closure." Functional Plant Biology 16, no. 5 (1989): 429. http://dx.doi.org/10.1071/pp9890429.
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Changes in the content of endogenous abscisic acid (ABA) were followed in glasshouse experiments during stomatal closure induced by drought in leaves of lupin (Lupinus cosentinii Guss. cv. Eregulla) and wheat (Triticum aestivum L. cvv. Gamenya and Warigal), species which differ in stomatal sensitivity to changes in leaf water potential. Increases in bulk leaf ABA concentration were closely correlated with decreases in leaf conductance in both species. In lupin, substantial increases in ABA and decreases in conductance occurred over a very narrow range of leaf water potential. ABA concentrations in wheat leaves were highly negatively correlated with bulk leaf turgor, but there was no significant relationship between ABA and turgor in lupin. However, ABA accumulated progressively in the leaves of both species as soil water content decreased. Stomatal closure in lupin could be induced by supplying exogenous ABA to detached leaves via the transpiration stream at concentrations of 10-4 to 10-2 mol m-3 of (+)-ABA. Abaxial stomata closed more readily than those on the adaxial surface in response to both drought and applied ABA. Stomatal response to ABA was not affected by the presence of the cytokinin zeatin, and zeatin by itself had no effect on conductance. When treatments designed to reduce endogenous cytokinin concentrations were imposed (prolonged leaf detachment or prior drought), stomatal response to low concentrations of ABA was enhanced. However, such treatments did not significantly change the stomatal response to high ABA concentrations, nor affect the stomatal conductance of leaves supplied with water alone. It is concluded that drought-induced stomatal closure could be mediated by ABA in both wheat and lupin, despite the initially small change in leaf water status in the latter species.
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Khan, Aziz, Jie Zheng, Daniel Kean Yuen Tan, Ahmad Khan, Kashif Akhtar, Xiangjun Kong, Fazal Munsif, et al. "Changes in Leaf Structural and Functional Characteristics when Changing Planting Density at Different Growth Stages Alters Cotton Lint Yield under a New Planting Model." Agronomy 9, no. 12 (December 7, 2019): 859. http://dx.doi.org/10.3390/agronomy9120859.
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Manipulation of planting density and choice of variety are effective management components in any cropping system that aims to enhance the balance between environmental resource availability and crop requirements. One-time fertilization at first flower with a medium plant stand under late sowing has not yet been attempted. To fill this knowledge gap, changes in leaf structural (stomatal density, stomatal length, stomata width, stomatal pore perimeter, and leaf thickness), leaf gas exchange, and chlorophyll fluorescence attributes of different cotton varieties were made in order to change the planting densities to improve lint yield under a new planting model. A two-year field evaluation was carried out on cotton varieties—V1 (Zhongmian-16) and V2 (J-4B)—to examine the effect of changing the planting density (D1, low, 3 × 104; D2, moderate, 6 × 104; and D3, dense, 9 × 104) on cotton lint yield, leaf structure, chlorophyll fluorescence, and leaf gas exchange attribute responses. Across these varieties, J-4B had higher lint yield compared with Zhongmian-16 in both years. Plants at high density had depressed leaf structural traits, net photosynthetic rate, stomatal conductance, intercellular CO2 uptake, quenching (qP), actual quantum yield of photosystem II (ΦPSII), and maximum quantum yield of PSII (Fv/Fm) in both years. Crops at moderate density had improved leaf gas exchange traits, stomatal density, number of stomata, pore perimeter, length, and width, as well as increased qP, ΦPSII, and Fv/Fm compared with low- and high-density plants. Improvement in leaf structural and functional traits contributed to 15.9%–10.7% and 12.3%–10.5% more boll m−2, with 20.6%–13.4% and 28.9%–24.1% higher lint yield averaged across both years, respectively, under moderate planting density compared with low and high density. In conclusion, the data underscore the importance of proper agronomic methods for cotton production, and that J-4B and Zhongmian-16 varieties, grown under moderate and lower densities, could be a promising option based on improved lint yield in subtropical regions.
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Nilsen, Erik T., David W. Webb, and Zhe Bao. "The function of foliar scales in water conservation: an evaluation using tropical-mountain, evergreen shrubs of the species Rhododendron in section Schistanthe (Ericaceae)." Australian Journal of Botany 62, no. 5 (2014): 403. http://dx.doi.org/10.1071/bt14072.
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Leaf scales (scarious trichomes) have putative significance to leaf water relations, energy balance, and gas exchange. A survey of leaf scales, stomata, and leaf morphology across 83 species of Rhododendron section Schistanthe in a common garden, at 1207-m elevation on Moana Loa, Hawai’i, was used to probe three possible functional models for scales on abaxial leaf surfaces. Scale density was commonly 10 mm–2, but densities up to 50 mm–2 occurred. The median stomatal density was 200 mm–2, but ranged up to 500 mm–2. Stomatal dispersion was grouped into four classes based on the proportion of stomata located under scales. Stomatal pore index decreased as scale density and scale importance factor increased. Thus, maximum stomatal conductance as represented by stomatal pore index decreased as the effect of scales on the leaf surface increased. Stomatal pore index increased as the elevation of the native range increased. However, the relative effects of scales on stomata peaked at mid-elevation. Principal components analysis indicated that the most important habitat factors determining both scale importance factor and stomatal pore index were elevation and growth form (epiphyte or terrestrial). Therefore, this survey indicated that scales serve a water conservation function, which is most effective at mid-elevation of the native range.
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Zwieniecki, Maciej A., Katrine S. Haaning, C. Kevin Boyce, and Kaare H. Jensen. "Stomatal design principles in synthetic and real leaves." Journal of The Royal Society Interface 13, no. 124 (November 2016): 20160535. http://dx.doi.org/10.1098/rsif.2016.0535.
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Stomata are portals in plant leaves that control gas exchange for photosynthesis, a process fundamental to life on Earth. Gas fluxes and plant productivity depend on external factors such as light, water and CO 2 availability and on the geometrical properties of the stoma pores. The link between stoma geometry and environmental factors has informed a wide range of scientific fields—from agriculture to climate science, where observed variations in stoma size and density are used to infer prehistoric atmospheric CO 2 content. However, the physical mechanisms and design principles responsible for major trends in stomatal patterning are not well understood. Here, we use a combination of biomimetic experiments and theory to rationalize the observed changes in stoma geometry. We show that the observed correlations between stoma size and density are consistent with the hypothesis that plants favour efficient use of space and maximum control of dynamic gas conductivity, and that the capacity for gas exchange in plants has remained constant over at least the last 325 Myr. Our analysis provides a new measure to gauge the relative performance of species based on their stomatal characteristics.
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Alves, Francisco Jose Basilio, and Antonio Lucineudo Oliveira Freire. "Gas Exchange of Mimosa tenuiflora (Willd.) Poiret Under Water Deficit and Rewatering." Journal of Agricultural Studies 7, no. 2 (October 30, 2019): 297. http://dx.doi.org/10.5296/jas.v7i4.15338.
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This research aimed to evaluate the physiological responses of Mimosa tenuiflora plants submitted to variable water availability conditions during the nursery stage. Twelve-month-old plants kept in plastic pots containing 5 kg of the substrate composed of the subsoil soil mixture and bovine manure (2:1) were submitted to two treatments: irrigated (control) and water stress, which was imposed through the suspension of irrigation, rewatering after seven days of stress. The relative water content (RWC) and stomatal parameters were evaluated. The M. tenuiflora plants responded quickly to the irrigation suspension, promoting the closure of the stomata, occurring reduction in stomatal conductance, transpiration rate and photosynthesis. The instantaneous efficiency in water use of plants under water deficit remained high only until the middle of the period when irrigation was suspended, and then declined until the last day of the water deficit. After rehydration, the plants showed recovery in all evaluated parameters, indicating that the level of stress imposed did not cause irreversible damages in the cells and tissues.
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Zhang, Dandan, Caijuan Tian, Kangquan Yin, Wenyi Wang, and Jin-Long Qiu. "Postinvasive Bacterial Resistance Conferred by Open Stomata in Rice." Molecular Plant-Microbe Interactions® 32, no. 2 (February 2019): 255–66. http://dx.doi.org/10.1094/mpmi-06-18-0162-r.
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Stomata are leaf pores that regulate gas exchange and water transpiration in response to environmental cues. They also function in innate immunity by limiting pathogen entry through actively closing in so-called stomatal defense. However, roles of stomata in plant disease resistance are not fully elucidated, especially in monocots. Here, we report that non–race specific resistance of the rice abscisic acid-deficient mutant Osaba1 to Xanthomonas oryzae pv. oryzae is due to increased stomatal conductance. Reducing stomatal conductance in the Osaba1 mutant increases its susceptibility to X. oryzae pv. oryzae. Artificial opening of stomata in wild-type plants leads to enhanced resistance to X. oryzae pv. oryzae. The rice mutant es1-1 with constitutively higher stomatal conductance exhibits strong resistance to X. oryzae pv. oryzae. Additionally, Osaba1 and es1-1 are resistant to X. oryzae pv. oryzicola. The data support that open stomata confer postinvasive resistance against bacterial pathogens in rice, and such resistance probably results from decreased leaf water potential. Our findings reveal a novel role of stomata in plant immunity through modulation of leaf water status, which provides physiological insight into the interactions between plant, pathogen, and environment.
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Driesen, Elisa, Wim Van den Ende, Maurice De Proft, and Wouter Saeys. "Influence of Environmental Factors Light, CO2, Temperature, and Relative Humidity on Stomatal Opening and Development: A Review." Agronomy 10, no. 12 (December 15, 2020): 1975. http://dx.doi.org/10.3390/agronomy10121975.
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Stomata, the microscopic pores surrounded by a pair of guard cells on the surfaces of leaves and stems, play an essential role in regulating the gas exchange between a plant and the surrounding atmosphere. Stomatal development and opening are significantly influenced by environmental conditions, both in the short and long term. The rapid rate of current climate change has been affecting stomatal responses, as a new balance between photosynthesis and water-use efficiency has to be found. Understanding the mechanisms involved in stomatal regulation and adjustment provides us with new insights into the ability of stomata to process information and evolve over time. In this review, we summarize the recent advances in research on the underlying mechanisms of the interaction between environmental factors and stomatal development and opening. Specific emphasis is placed on the environmental factors including light, CO2 concentration, ambient temperature, and relative humidity, as these factors play a significant role in understanding the impact of global climate change on plant development.
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Yun, Kyungdahm, Dennis Timlin, and Soo-Hyung Kim. "Coupled Gas-Exchange Model for C4 Leaves Comparing Stomatal Conductance Models." Plants 9, no. 10 (October 14, 2020): 1358. http://dx.doi.org/10.3390/plants9101358.
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Plant simulation models are abstractions of plant physiological processes that are useful for investigating the responses of plants to changes in the environment. Because photosynthesis and transpiration are fundamental processes that drive plant growth and water relations, a leaf gas-exchange model that couples their interdependent relationship through stomatal control is a prerequisite for explanatory plant simulation models. Here, we present a coupled gas-exchange model for C4 leaves incorporating two widely used stomatal conductance submodels: Ball–Berry and Medlyn models. The output variables of the model includes steady-state values of CO2 assimilation rate, transpiration rate, stomatal conductance, leaf temperature, internal CO2 concentrations, and other leaf gas-exchange attributes in response to light, temperature, CO2, humidity, leaf nitrogen, and leaf water status. We test the model behavior and sensitivity, and discuss its applications and limitations. The model was implemented in Julia programming language using a novel modeling framework. Our testing and analyses indicate that the model behavior is reasonably sensitive and reliable in a wide range of environmental conditions. The behavior of the two model variants differing in stomatal conductance submodels deviated substantially from each other in low humidity conditions. The model was capable of replicating the behavior of transgenic C4 leaves under moderate temperatures as found in the literature. The coupled model, however, underestimated stomatal conductance in very high temperatures. This is likely an inherent limitation of the coupling approaches using Ball–Berry type models in which photosynthesis and stomatal conductance are recursively linked as an input of the other.
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Raissig, Michael T., Emily Abrash, Akhila Bettadapur, John P. Vogel, and Dominique C. Bergmann. "Grasses use an alternatively wired bHLH transcription factor network to establish stomatal identity." Proceedings of the National Academy of Sciences 113, no. 29 (July 5, 2016): 8326–31. http://dx.doi.org/10.1073/pnas.1606728113.
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Stomata, epidermal valves facilitating plant–atmosphere gas exchange, represent a powerful model for understanding cell fate and pattern in plants. Core basic helix–loop–helix (bHLH) transcription factors regulating stomatal development were identified in Arabidopsis, but this dicot’s developmental pattern and stomatal morphology represent only one of many possibilities in nature. Here, using unbiased forward genetic screens, followed by analysis of reporters and engineered mutants, we show that stomatal initiation in the grass Brachypodium distachyon uses orthologs of stomatal regulators known from Arabidopsis but that the function and behavior of individual genes, the relationships among genes, and the regulation of their protein products have diverged. Our results highlight ways in which a kernel of conserved genes may be alternatively wired to produce diversity in patterning and morphology and suggest that the stomatal transcription factor module is a prime target for breeding or genome modification to improve plant productivity.
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Sun, Zhuangzhuang, Yunlin Song, Qing Li, Jian Cai, Xiao Wang, Qin Zhou, Mei Huang, and Dong Jiang. "An Integrated Method for Tracking and Monitoring Stomata Dynamics from Microscope Videos." Plant Phenomics 2021 (April 9, 2021): 1–11. http://dx.doi.org/10.34133/2021/9835961.
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Patchy stomata are a common and characteristic phenomenon in plants. Understanding and studying the regulation mechanism of patchy stomata are of great significance to further supplement and improve the stomatal theory. Currently, the common methods for stomatal behavior observation are based on static images, which makes it difficult to reflect dynamic changes of stomata. With the rapid development of portable microscopes and computer vision algorithms, it brings new chances for stomatal movement observation. In this study, a stomatal behavior observation system (SBOS) was proposed for real-time observation and automatic analysis of each single stoma in wheat leaf using object tracking and semantic segmentation methods. The SBOS includes two modules: the real-time observation module and the automatic analysis module. The real-time observation module can shoot videos of stomatal dynamic changes. In the automatic analysis module, object tracking locates every single stoma accurately to obtain stomatal pictures arranged in time-series; semantic segmentation can precisely quantify the stomatal opening area (SOA), with a mean pixel accuracy (MPA) of 0.8305 and a mean intersection over union (MIoU) of 0.5590 in the testing set. Moreover, we designed a graphical user interface (GUI) so that researchers could use this automatic analysis module smoothly. To verify the performance of the SBOS, the dynamic changes of stomata were observed and analyzed under chilling. Finally, we analyzed the correlation between gas exchange and SOA under drought stress, and the correlation coefficients between mean SOA and net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr) are 0.93, 0.96, 0.96, and 0.97.
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Grossnickle, Steven C., and John H. Russell. "Gas exchange processes of yellow-cedar (Chamaecyparis nootkatensis) in response to environmental variables." Canadian Journal of Botany 69, no. 12 (December 1, 1991): 2684–91. http://dx.doi.org/10.1139/b91-337.
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Yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) gas exchange processes were measured in response to the following primary environmental variables: photosynthetically active radiation, vapour pressure deficit, root temperature, and soil moisture. Under nonlimiting edaphic conditions, maximum stomatal conductance and maximum CO2 assimilation increased rapidly as photosynthetically active radiation increased from 0 to 200 μmol∙m−2∙s−1 and from 0 to 500 μmol∙m−2∙s−1, respectively. Thereafter, greater photosynthetically active radiation levels only resulted in minor increases in stomatal conductance and CO2 assimilation. Maximum stomatal conductance and maximum CO2 assimilation declined in a concave manner as vapour pressure deficit increased from 1 to 5 kPa. Response surface model for stomatal conductance showed vapour pressure deficit was the primary influence after light had caused initial stomatal opening. Response surface modeling approach showed CO2 assimilation increased as photosynthetically active radiation increased, but increased vapour pressure deficit resulted in a suppression of CO2 assimilation. Response surface model showed internal CO2 concentration declined sharply as photosynthetically active radiation increased from 0 to 500 μmol∙m−2∙s−1, but it remained constant with increasing vapour pressure deficit. Decreasing root temperature resulted in a continual decline in CO2 assimilation and stomatal conductance from 22 to 1 °C, while internal CO2 concentration declined from 22 to 13 °C with little change between 13 and 1 °C. As predawn shoot water potential decreased from −0.5 to −2.0 MPa, CO2 assimilation declined in a linear manner, while stomatal conductance and internal CO2 concentration declined in a concave manner. Key words: Chamaecyparis nootkatensis, CO2 assimilation, stomatal conductance, internal CO2 concentration, photosynthetically active radiation, vapour pressure deficit, root temperature, predawn shoot water potential.
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Ooba, Makoto, and Hidenori Takahashi. "Effect of asymmetric stomatal response on gas-exchange dynamics." Ecological Modelling 164, no. 1 (June 2003): 65–82. http://dx.doi.org/10.1016/s0304-3800(03)00012-7.
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Liao, Jian-Xiong, Jie Chang, and Gen-Xuan Wang. "Stomatal density and gas exchange in six wheat cultivars." Cereal Research Communications 33, no. 4 (December 2005): 719–26. http://dx.doi.org/10.1556/crc.33.2005.2-3.140.
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Schulze, ED. "Whole-Plant Responses to Drought." Functional Plant Biology 13, no. 1 (1986): 127. http://dx.doi.org/10.1071/pp9860127.
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The partitioning of carbon and interactions which cause limitations on gas exchange and growth under conditions of a limited supply of water and nutrients are discussed. Possible mechanisms of effects of air humidity on stomatal functioning and carbon assimilation are described. Also, it is shown that stomata respond to a signal from the root when the soil dries out prior to leaf wilting. Stomatal conductance determines canopy transpiration if the aerodynamic boundary layer resistance is low, such as in trees. Water shortage significantly affects extension growth and the root-shoot ratio at the whole- plant level. But experiments with xylem-tapping mistletoes show that stem growth can also be promoted by the presence of the mistletoe even when there is no apparent signal from the subtending shoot except the flow in the stem xylem. It appears that the internal plant water status may not affect gas exchange and carbon partitioning unless the plant fails to maintain a flow of water through the leaf epidermis and root tip.
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Torii, Keiko U. "Stomatal development in the context of epidermal tissues." Annals of Botany 128, no. 2 (April 20, 2021): 137–48. http://dx.doi.org/10.1093/aob/mcab052.
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Abstract Background Stomata are adjustable pores on the surface of plant shoots for efficient gas exchange and water control. The presence of stomata is essential for plant growth and survival, and the evolution of stomata is considered as a key developmental innovation of the land plants, allowing colonization on land from aquatic environments some 450 million years ago. In the past two decades, molecular genetic studies using the model plant Arabidopsis thaliana identified key genes and signalling modules that regulate stomatal development: master regulatory transcription factors that orchestrate cell state transitions and peptide–receptor signal transduction pathways, which, together, enforce proper patterning of stomata within the epidermis. Studies in diverse plant species, ranging from bryophytes to angiosperm grasses, have begun to unravel the conservation and uniqueness of the core modules in stomatal development. Scope Here, I review the mechanisms of stomatal development in the context of epidermal tissue patterning. First, I introduce the core regulatory mechanisms of stomatal patterning and differentiation in the model species A. thaliana. Subsequently, experimental evidence is presented supporting the idea that different cell types within the leaf epidermis, namely stomata, hydathodes pores, pavement cells and trichomes, either share developmental origins or mutually influence each other’s gene regulatory circuits during development. Emphasis is placed on extrinsic and intrinsic signals regulating the balance between stomata and pavement cells, specifically by controlling the fate of stomatal-lineage ground cells (SLGCs) to remain within the stomatal cell lineage or differentiate into pavement cells. Finally, I discuss the influence of intertissue layer communication between the epidermis and underlying mesophyll/vascular tissues on stomatal differentiation. Understanding the dynamic behaviours of stomatal precursor cells and their differentiation in the broader context of tissue and organ development may help design plants tailored for optimal growth and productivity in specific agricultural applications and a changing environment.
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Pimentel, Carlos, Rafael Vasconcelos Ribeiro, Mauro Guida dos Santos, Ricardo Ferraz de Oliveira, and Eduardo Caruso Machado. "Effects of changes in the photosynthetic photon flux density on net gas exchange of Citrus limon and Nicotiana tabacum." Brazilian Journal of Plant Physiology 16, no. 2 (August 2004): 77–82. http://dx.doi.org/10.1590/s1677-04202004000200002.
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The objective of this study was to evaluate the effects of changes in the photosynthetic photon flux density (PPFD) on net gas exchange of Citrus limon, a woody species, and Nicotiana tabacum, an herbaceous species. When PPFD was increased from 50 to 350 mumol.m-2.s-1 and returned to 50 mumol.m-2.s-1 after 60 min, the CO2 assimilation rate (A) increased and stabilized after 15 min in both species. Stomatal conductance (g s), however, continued to increase. After returning to low PPFD, A immediately diminished to a low value for both lemon and tobacco. Stomatal conductance of lemon diminished slowly over 60 min, whereas g s for tobacco took only 15 min to decrease. This difference in behavior is probably due to over-sensitivity of stomata of woody species, such as Citrus, when exposed to high light, retarding stomatal closure on return to low PPFD. Furthermore, when lemon, growing at a PPFD of 300 mumol.m-2.s-1, was submitted to a step increase of 600 mumol.m-2.s-1, there was an oscillatory behavior of A and g s requiring 150 min to stabilize. The causes of this behavior are discussed with respect to improved intrinsic water use efficiency by stomatal closure.
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Lima Filho, José Moacir Pinheiro. "Gas exchange of the umbu tree under semi-arid conditions." Revista Brasileira de Fruticultura 26, no. 2 (August 2004): 206–8. http://dx.doi.org/10.1590/s0100-29452004000200006.
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A study was carried out at Embrapa Semi-Árido, Petrolina-PE, Brazil, aiming to understand the gas exchange process of the umbu tree (Spondias tuberosa Arr. Cam.) in the dry and rainy seasons. Stomatal conductance, transpiration, photosynthesis and internal CO2 concentration were obtained with a portable infrared gas analyzer (IRGA). During the dry season the umbu tree showed a much lower stomatal conductance early in the morning, as soon as the vapor pressure deficit increased, apparently affecting CO2 assimilation more than transpiration. The highest values were detected around 6:00 am but decreased to the lowest points between 10:00 am and 2:00 pm. During the rainy season, however, stomatal conductance, transpiration and photosynthesis were significantly higher, reaching the highest values between 8:00 and 10:00 am and the lowest around 2:00 pm. It was also observed at 4:00 pm, mainly during the rainy season, an increase on these variables indicating that the umbu tree exhibits a two-picked daily course of gas exchange.
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Bheemanahalli, Raju, Chaoxin Wang, Elfadil Bashir, Anuj Chiluwal, Meghnath Pokharel, Ramasamy Perumal, Naghmeh Moghimi, Troy Ostmeyer, Doina Caragea, and S. V. Krishna Jagadish. "Classical phenotyping and deep learning concur on genetic control of stomatal density and area in sorghum." Plant Physiology 186, no. 3 (April 15, 2021): 1562–79. http://dx.doi.org/10.1093/plphys/kiab174.
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Abstract Stomatal density (SD) and stomatal complex area (SCA) are important traits that regulate gas exchange and abiotic stress response in plants. Despite sorghum (Sorghum bicolor) adaptation to arid conditions, the genetic potential of stomata-related traits remains unexplored due to challenges in available phenotyping methods. Hence, identifying loci that control stomatal traits is fundamental to designing strategies to breed sorghum with optimized stomatal regulation. We implemented both classical and deep learning methods to characterize genetic diversity in 311 grain sorghum accessions for stomatal traits at two different field environments. Nearly 12,000 images collected from abaxial (Ab) and adaxial (Ad) leaf surfaces revealed substantial variation in stomatal traits. Our study demonstrated significant accuracy between manual and deep learning methods in predicting SD and SCA. In sorghum, SD was 32%–39% greater on the Ab versus the Ad surface, while SCA on the Ab surface was 2%–5% smaller than on the Ad surface. Genome-Wide Association Study identified 71 genetic loci (38 were environment-specific) with significant genotype to phenotype associations for stomatal traits. Putative causal genes underlying the phenotypic variation were identified. Accessions with similar SCA but carrying contrasting haplotypes for SD were tested for stomatal conductance and carbon assimilation under field conditions. Our findings provide a foundation for further studies on the genetic and molecular mechanisms controlling stomata patterning and regulation in sorghum. An integrated physiological, deep learning, and genomic approach allowed us to unravel the genetic control of natural variation in stomata traits in sorghum, which can be applied to other plants.
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Mwamlima, Louis Hortensius, Josephine Pamela Ouma, and Erick Kimutai Cheruiyot. "Leaf Gas Exchange and Root Nodulation Respond to Planting Density in Soybean [Glycine max (L) Merrill]." Advances in Agriculture 2020 (January 30, 2020): 1–7. http://dx.doi.org/10.1155/2020/6424389.
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Planting density influences structural characteristics and affects mineral nutrient acquisition, irradiance and photosynthesis amongst plants. An experiment was conducted to determine the effect of planting density on leaf gas exchange and nodulation of soybean (Glycine max (L) Merrill). The experiment was conducted as a randomized complete block design (RCBD) in a 5 by 2 factorial treatment arrangement and was replicated three times. Planting density (10, 12, 20, 40, and 80 plants m−2) and soybean varieties (EAI 3600 and DPSB 19) were first and second factors, respectively. Collected data were subjected to analysis of variance in GENSTAT. Significantly different treatment means were separated using Tukey’s honestly significant difference test at 0.05 significance level. Higher planting density significantly increased (p<0.001) interception of photosynthetically active radiation. Increasing number of plants per unit area significantly (p<0.001) reduced root nodulation, stomata conductance, sub-stomatal CO2 concentration, photosynthetic and transpiration rates. Total chlorophyll content was not responsive to planting density though concentration of chlorophyll “a” content was significantly (p<0.005) higher at lower plant density than at higher plant density. Soil moisture status increased with reduction in plant density. Indeterminate variety DPSB 19 had higher rates of stomata conductance, photosynthesis and sub-stomatal CO2 concentration compared to determinate variety EAI 3600.
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Marler, Thomas E., and Michael V. Mickelbart. "Repeated Mechanical Stress from Leaf Cuvette Influences Leaf Gas Exchange." HortScience 27, no. 5 (May 1992): 432–34. http://dx.doi.org/10.21273/hortsci.27.5.432.
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Long-term effects on stomatal conductance of mechanical stress from repeated clamping of a porometer leaf cuvette to laminae of avocado (Persea americana Miller), carambola (Averrhoa carambolu L.), hibiscus (Hibiscus rosa-sinensis L.), mango (Mangifera indica L.), and sugar apple (Annona squamosa L.) plants were determined under glasshouse conditions. Following 10 weeks of applying the mechanical stimulus seven times during every 4th day to mature leaves, stomatal conductance was lower than for untreated leaves of all species except mango. Similarly, following 10.5 weeks of applying the stimulus one time every 4th day to expanding leaves of avocado, carambola, hibiscus, and sugar apple, stomatal conductance was lower than for untreated leaves of the same age in all species except hibiscus. Carambola and sugar apple were more sensitive to the mechanical stress than the other species. Thus, the indirect effect of leaf chamber clamping on gas exchange should be known before any conclusions are formulated regarding environmental, cultural, or genetic effects on gas exchange. Random leaf samples from a canopy instead of measurements on a fixed set of leaves may be more appropriate for repeated determinations of leaf gas exchange on a set of plants.
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Lloyd, J., SC Wong, JM Styles, D. Batten, R. Priddle, C. Turnbull, and CA Mcconchie. "Measuring and Modelling Whole-Tree Gas Exchange." Functional Plant Biology 22, no. 6 (1995): 987. http://dx.doi.org/10.1071/pp9950987.
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Diurnal patterns of CO2 and water vapour exchange were determined for Macadamia integrifolia and Litchi chinensis trees enclosed in whole-tree gas exchange chambers at Alstonville, New South Wales (28.5�S) during October and November 1991. Whole-tree gas exchange responses to photon irradiance (I), ambient partial pressure of CO2 (Ca) and vapour pressure deficit (D) were similar to those normally observed for individual leaves. Nevertheless, at a given I (above approximately 500 μmol quanta m-2, s-1) stomatal conductances (gs) and CO2 assimilation rates (A) were higher under overcast, as opposed to clear sky conditions. This difference was maintained even when A and gs were examined as a function of sun angle. Combined with a simple light interception model, nested quadratic equations combining stomatal responses and biochemical characteristics of individual leaves were found to provide excellent descriptions of the gas exchange responses of the isolated trees. This indicates a close to optimal partitioning of photosynthetic machinery throughout the canopy. From the whole-tree gas exchange model it was found that higher A and gs under overcast conditions are attributable to both lower T1 and D as well as to a more uniform distribution of irradiance across the canopy surface.
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Doll, Yuki, Hiroyuki Koga, and Hirokazu Tsukaya. "The diversity of stomatal development regulation inCallitricheis related to the intrageneric diversity in lifestyles." Proceedings of the National Academy of Sciences 118, no. 14 (March 29, 2021): e2026351118. http://dx.doi.org/10.1073/pnas.2026351118.
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Stomata, the gas exchange structures of plants, are formed by the division and differentiation of stem cells, or meristemoids. Although diverse patterns of meristemoid behavior have been observed among different lineages of land plants, the ecological significance and diversification processes of these different patterns are not well understood. Here we describe an intrageneric diversity in the patterns of meristemoid division within the ecologically diverse genusCallitriche(Plantaginaceae). Meristemoids underwent a series of divisions before differentiating into stomata in the terrestrial species ofCallitriche, but these divisions did not occur in amphibious species, which can grow in both air and water, in which meristemoids differentiated directly into stomata. These findings imply the adaptive significance of diversity in meristemoid division. Molecular genetic analyses showed that the different expression times of the stomatal key transcription factors SPEECHLESS and MUTE, which maintain and terminate the meristemoid division, respectively, underlie the different division patterns of meristemoids. Unlike terrestrial species, amphibious species prematurely expressedMUTEimmediately after expressingSPEECHLESS, which corresponded to their early termination of stomatal division. By linking morphological, ecological, and genetic elements of stomatal development, this study provides significant insight that should aid ecological evolutionary developmental biology investigations of stomata.
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Hu, Meng, Shao Zhong Kang, Tai Sheng Du, and Ling Tong. "Another View of Gas Exchange Model: Reflection of Leaf Surface Air to Stomatal Conductance." Advanced Materials Research 113-116 (June 2010): 14–17. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.14.
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A reflection function was established, based on leaf gas exchange process and tested with experimental data of eight kinds of plants, i.e. tomato, muskmelon, capsicum, maize, grape, onion, Haloxylon Ammodendron Bunge and Caragana Karshiskii Kom, with multifarious biological characteristic, water and growing status. The function indicated that the leaf stomatal conductance could be linearly reflected by the ratio of humidity and CO2 concentration at leaf surface, and the behaviour of its slope could be recognized as an indicator of leaf gas exchange efficiency, which had a negative relationship with leaf water use efficiency (WUE). The results maybe increase our understanding of potential influences of leaf stomatal conductance on photosynthetic and transpiration gas exchange and leaf WUE.
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Feild, Taylor S., Garland R. Upchurch, David S. Chatelet, Timothy J. Brodribb, Kunsiri C. Grubbs, Marie-Stéphanie Samain, and Stefan Wanke. "Fossil evidence for low gas exchange capacities for Early Cretaceous angiosperm leaves." Paleobiology 37, no. 2 (2011): 195–213. http://dx.doi.org/10.1666/10015.1.
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The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian—early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.
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Nagatoshi, Yukari, Nobutaka Mitsuda, Maki Hayashi, Shin-ichiro Inoue, Eiji Okuma, Akihiro Kubo, Yoshiyuki Murata, et al. "GOLDEN 2-LIKE transcription factors for chloroplast development affect ozone tolerance through the regulation of stomatal movement." Proceedings of the National Academy of Sciences 113, no. 15 (March 28, 2016): 4218–23. http://dx.doi.org/10.1073/pnas.1513093113.
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Stomatal movements regulate gas exchange, thus directly affecting the efficiency of photosynthesis and the sensitivity of plants to air pollutants such as ozone. The GARP family transcription factors GOLDEN 2-LIKE1 (GLK1) and GLK2 have known functions in chloroplast development. Here, we show thatArabidopsis thaliana(A. thaliana) plants expressing the chimeric repressors for GLK1 and -2 (GLK1/2-SRDX) exhibited a closed-stomata phenotype and strong tolerance to ozone. By contrast, plants that overexpress GLK1/2 exhibited an open-stomata phenotype and higher sensitivity to ozone. The plants expressingGLK1-SRDXhad reduced expression of the genes for inwardly rectifying K+(K+in) channels and reduced K+inchannel activity. Abscisic acid treatment did not affect the stomatal phenotype of35S:GLK1/2-SRDXplants or the transcriptional activity for K+inchannel gene, indicating that GLK1/2 act independently of abscisic acid signaling. Our results indicate that GLK1/2 positively regulate the expression of genes for K+inchannels and promote stomatal opening. Because the chimeric GLK1-SRDX repressor driven by a guard cell-specific promoter induced a closed-stomata phenotype without affecting chloroplast development in mesophyll cells, modulating GLK1/2 activity may provide an effective tool to control stomatal movements and thus to confer resistance to air pollutants.
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Saeed, Ibrahim A. M., Ann E. MacGuidwin, and Douglas I. Rouse. "Synergism of Pratylenchus penetrans and Verticillium dahliae Manifested by Reduced Gas Exchange in Potato." Phytopathology® 87, no. 4 (April 1997): 435–39. http://dx.doi.org/10.1094/phyto.1997.87.4.435.
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The effects of solitary and concurrent infection by Pratylenchus pene-trans and Verticillium dahliae on gas exchange of Russet Burbank potato (Solanum tuberosum) were studied in growth chamber experiments. Treatments were P. penetrans at low, medium, and high density; V. dahliae alone at one initial density; the combination of the nematode at these three densities and V. dahliae; and a noninfested control. Gas exchange parameters of leaf cohorts of different ages in the different treatments were repeatedly measured with a Li-Cor LI-6200 portable photosynthesis system. At 45 days after planting, joint infection significantly reduced net photosynthesis, stomatal conductance, and transpiration of 1- to 25-day-old leaf cohorts. Intercellular CO2 levels were significantly increased by co-infection, especially in older leaves. The synergistic effect of co-infection on gas exchange parameters was greater in the oldest cohort than in the youngest cohort. No consistent effects on leaf gas exchange parameters were observed in plants infected by the nematode or the fungus alone. The relationship between the assimilation rate and stomatal conductance remained linear regardless of solitary or concomitant infection, indicating that stomatal factors are primarily responsible for regulating photosynthesis. The significant reduction of gas exchange in leaves of co-infected plants without reduction in intercellular CO2 concentrations suggests that nonstomatal factors also play a role when both organisms are present.
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Wei, Hongbin, Yifeng Jing, Lei Zhang, and Dexin Kong. "Phytohormones and their crosstalk in regulating stomatal development and patterning." Journal of Experimental Botany 72, no. 7 (January 29, 2021): 2356–70. http://dx.doi.org/10.1093/jxb/erab034.
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Abstract Phytohormones play important roles in regulating various aspects of plant growth and development as well as in biotic and abiotic stress responses. Stomata are openings on the surface of land plants that control gas exchange with the environment. Accumulating evidence shows that various phytohormones, including abscisic acid, jasmonic acid, brassinosteroids, auxin, cytokinin, ethylene, and gibberellic acid, play many roles in the regulation of stomatal development and patterning, and that the cotyledons/leaves and hypocotyls/stems of Arabidopsis exhibit differential responsiveness to phytohormones. In this review, we first discuss the shared regulatory mechanisms controlling stomatal development and patterning in Arabidopsis cotyledons and hypocotyls and those that are distinct. We then summarize current knowledge of how distinct hormonal signaling circuits are integrated into the core stomatal development pathways and how different phytohormones crosstalk to tailor stomatal density and spacing patterns. Knowledge obtained from Arabidopsis may pave the way for future research to elucidate the effects of phytohormones in regulating stomatal development and patterning in cereal grasses for the purpose of increasing crop adaptive responses.
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Robinson, SP, WJR Grant, and BR Loveys. "Stomatal Limitation of Photosynthesis in Abscisic Acid-Treated and in Water-Stressed Leaves Measured at Elevated CO2." Functional Plant Biology 15, no. 4 (1988): 495. http://dx.doi.org/10.1071/pp9880495.
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Feeding 10-5M (�)-abscisic acid (ABA) via the petioles of detached leaves of apricot (Prunus armeniaca) or sunflower (Helianthus annuus) decreased stomatal conductance and assimilation rate but not the calculated intercellular CO2 concentration (Ci) suggesting non-stomatal as well as stomatal inhibition of photosynthesis. Evidence for non-stomatal inhibition was not observed in spinach (Spinacia oleracea). There was no significant decrease in rates of electron transport nor ribulosebisphosphate carboxylase (Rubisco) activity in intact chloroplasts isolated from ABA-treated sunflower leaves. Oxygen evolution by leaf discs with 3% CO2 in the gas phase was inhibited in ABA- treated sunflower and apricot leaves but not in spinach; the inhibition was only half as great as the inhibition of assimilation rate at ambient CO2. The quantum yield of oxygen evolution decreased in ABA-treated sunflower leaves in proportion to the decrease in the light-saturated rate. There was no significant difference in room temperature chlorophyll fluorescence of ABA-treated leaves compared to controls. Stomatal conductance of sunflower leaves decreased by more than 90% when the CO2 concentration was increased from 340 ppm to 1000 ppm but at much higher CO2 concentrations the stomata appeared to reopen. Stomatal conductance at 2-3% CO2 (20 000-30 000 ppm) was 50% that at ambient CO2. This reopening of stomata at high CO2 was inhibited in previously water-stressed or ABA-treated plants. In unstressed leaves, the maximum rate of oxygen evolution occurred at 0.5-2% CO2 but in ABA-treated leaves 10-15% CO2 was required for maximum rates. It is suggested that stomatal closure may limit photosynthesis in ABA-treated or previously water-stressed leaves even at the relatively high CO2 concentrations normally used in the leaf disc oxygen electrode. The inhibition of photosynthesis by ABA is largely overcome at saturating CO2. The apparent non-stomatal inhibition suggested by gas exchange measurements and the decreased quantum yield could be explained by patchy stomatal closure in response to ABA.
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Hu, Hening, and Darrell Sparks. "Zinc Deficiency Inhibits Chlorophyll Synthesis and Gas Exchange in `Stuart' Pecan." HortScience 26, no. 3 (March 1991): 267–68. http://dx.doi.org/10.21273/hortsci.26.3.267.
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Leaves of `Stuart' pecan [Carya illinoensis (Wangenh.) C. Koch] with various levels of Zn deficiency were analyzed for physiological indicators of leaf vigor. Leaf chlorophyll content, stomatal conductance, and net photosynthesis were adversely affected by Zn deficiency. In leaves with severe Zn deficiency, each of these indicators increased 3- to 5-fold with a doubling of leaf Zn concentration, but stabilized as leaf Zn approached the sufficiency range (14 μg·g-1). High intercellular CO2 associated with low net photosynthesis indicates that stomatal aperture was not the cause of the reduction of net photosynthesis under Zn deficiency.
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Gebre, G. Michael, and Michael R. Kuhns. "Effects of water stress preconditioning on gas exchange and water relations of Populusdeltoides clones." Canadian Journal of Forest Research 23, no. 7 (July 1, 1993): 1291–97. http://dx.doi.org/10.1139/x93-165.
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The effect of water stress preconditioning on gas exchange was investigated in greenhouse-grown eastern Cottonwood (Populusdeltoides Bartr.). Two clones from southern Ohio (Ohio Red) and eastern Nebraska (Platte) were selected based on their differences in dehydration tolerance. Plants were either watered every day (control) or preconditioned by watering every 3 (TRT 1) or 4 days (TRT 2). After three dry–wet cycles (TRT 2), predawn leaf water potential (Ψw) of Ohio Red was −0.32 MPa; net photosynthesis and stomatal conductance were reduced to 13 and 9% of control, respectively. Eighteen hours after rewatering, photosynthesis recovered (103% of control), while stomatal conductance was 60% of control. Net photosynthesis of Platte was reduced to 43% and stomatal conductance to 32% of control (Ψw−0.21 MPa), and neither recovered fully when rewatered. After six dry–wet cycles (TRT 2), net photosynthesis of Ohio Red was reduced by 50%, though Ψw was −0.48 MPa. Clones showed an osmotic adjustment of −0.2 MPa after three (Platte) and six cycles (Ohio Red). When all preconditioned plants were stressed for 10 days, Ψw was −1.05 MPa and plants had negative net photosynthesis and no osmotic adjustment. Net photosynthetic rate of Ohio Red recovered (100% of control) on the second day of rewatering (stomatal conductance 68%), while Platte had not recovered (71%) by the fourth day (stomatal conductance 95%). These differences suggest that recovery of photosynthesis was limited mainly by stomatal factors in Ohio Red and nonstomatal factors in Platte. The preconditioning treatment also seems to have benefitted Ohio Red.
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Rose, Mary Ann, and Mark A. Rose. "Oscillatory Transpiration May Complicate Stomatal Conductance and Gas-exchange Measurements." HortScience 29, no. 6 (June 1994): 693–94. http://dx.doi.org/10.21273/hortsci.29.6.693.
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A closed-loop photosynthesis system and a heat-balance sap-flow gauge independently confirmed oscillatory transpiration in a greenhouse-grown Rosa hybrids L. Repetitive sampling revealed 60-minute synchronized oscillations in CO2-exchange rate, stomatal conductance, and whole-plant sap-flow rate. To avoid confusing cyclical plant responses with random noise in measurement, we suggest that gas-exchange protocols begin with frequent, repetitive measurements to determine whether transpiration is stable or oscillating. Single measurements of individual plants would be justified only when transpiration is steady state.
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Zeng, Scott M., Emily K. W. Lo, Bryna J. Hazelton, Miguel F. Morales, and Keiko U. Torii. "Effective range of non-cell autonomous activator and inhibitor peptides specifying plant stomatal patterning." Development 147, no. 17 (August 18, 2020): dev192237. http://dx.doi.org/10.1242/dev.192237.
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ABSTRACTStomata are epidermal valves that facilitate gas exchange between plants and their environment. Stomatal patterning is regulated by the EPIDERMAL PATTERING FACTOR (EPF) family of secreted peptides: EPF1 enforces stomatal spacing, whereas EPIDERMAL PATTERNING FACTOR-LIKE9 (EPFL9), also known as Stomagen, promotes stomatal development. It remains unknown, however, how far these signaling peptides act. Utilizing Cre-lox recombination-based mosaic sectors that overexpress either EPF1 or Stomagen in Arabidopsis cotyledons, we reveal a range within the epidermis and across the cell layers in which these peptides influence patterns. To determine their effective ranges quantitatively, we developed a computational pipeline, SPACE (stomata patterning autocorrelation on epidermis), that describes probabilistic two-dimensional stomatal distributions based upon spatial autocorrelation statistics used in astrophysics. The SPACE analysis shows that, whereas both peptides act locally, the inhibitor EPF1 exerts longer range effects than the activator Stomagen. Furthermore, local perturbation of stomatal development has little influence on global two-dimensional stomatal patterning. Our findings conclusively demonstrate the nature and extent of EPF peptides as non-cell autonomous local signals and provide a means for quantitative characterization of complex spatial patterns in development.This article has an associated ‘The people behind the papers’ interview.
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KRAALINGEN, D. W. G. "Implications of non-uniform stomatal closure on gas exchange calculations." Plant, Cell and Environment 13, no. 9 (December 1990): 1001–4. http://dx.doi.org/10.1111/j.1365-3040.1990.tb01993.x.
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Koman, Volodymyr B., Tedrick T. S. Lew, Min Hao Wong, Seon-Yeong Kwak, Juan P. Giraldo, and Michael S. Strano. "Persistent drought monitoring using a microfluidic-printed electro-mechanical sensor of stomata in planta." Lab on a Chip 17, no. 23 (2017): 4015–24. http://dx.doi.org/10.1039/c7lc00930e.
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Repellin, Anne, Serge Braconnier, Daniel Laffray, Claude Daniel, and Yasmine Zuily-Fodil. "Water relations and gas exchange in young coconut palm (Cocos nucifera L.) as influenced by water deficit." Canadian Journal of Botany 75, no. 1 (January 1, 1997): 18–27. http://dx.doi.org/10.1139/b97-003.
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Drought is the main climatic limitation to coconut palm (Cocos nucifera L.) production. To identify early screening parameters for drought resistance, physiological responses to water deficit were investigated for the first time using containerized young plants grown outside. Three varieties were studied: 'West Coast Tall' (drought avoiding), 'Malayan Yellow Dwarf' (drought susceptible), and their progeny, the hybrid 'PB 121' (drought resistant). Leaf water status (relative water content, leaf water potential) and leaf gas exchange parameters (stomatal conductance to water vapor, net photosynthetic rate, and leaf internal CO2 concentration) were measured throughout a drying cycle induced by withholding watering. On fully hydrated plants, the sensitivity of stomata to atmospheric water vapor deficit was also investigated. In the three varieties, stomatal conductance to water vapor declined before leaf water status parameters were affected. The existence of a root-to-shoot communication system was proposed. Net photosynthetic rate was highly dependent on stomatal aperture, but nonstomatal factors also participated in the reduction of CO2 fixation. Since gas exchange rates were equally sensitive to drought in the three varieties, they could not be used as screening parameters for drought resistance. Under severe drought stress, both relative water content and leaf water potential differed significantly among populations. 'West Coast Tall' maintained a higher leaf water status than 'Malayan Yellow Dwarf'. Remarkably, the water status parameters of 'PB 121' were intermediate between those of the two parents. Similar ranking was obtained in experiments with excised leaflets. The high reproductibility of the results suggests that leaf water status parameters might be useful as early selection criteria for drought resistance in coconut palm. Key words: Cocos nucifera L., gas exchange, leaf water status parameters, water deficit, water relations.
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Beerling, David J. "Gas valves, forests and global change: a commentary on Jarvis (1976) ‘The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field’." Philosophical Transactions of the Royal Society B: Biological Sciences 370, no. 1666 (April 19, 2015): 20140311. http://dx.doi.org/10.1098/rstb.2014.0311.
Full textAbstract:
Microscopic turgor-operated gas valves on leaf surfaces—stomata—facilitate gas exchange between the plant and the atmosphere, and respond to multiple environmental and endogenous cues. Collectively, stomatal activities affect everything from the productivity of forests, grasslands and crops to biophysical feedbacks between land surface vegetation and climate. In 1976, plant physiologist Paul Jarvis reported an empirical model describing stomatal responses to key environmental and plant conditions that predicted the flux of water vapour from leaves into the surrounding atmosphere. Subsequent theoretical advances, building on this earlier approach, established the current paradigm for capturing the physiological behaviour of stomata that became incorporated into sophisticated models of land carbon cycling. However, these models struggle to accurately predict observed trends in the physiological responses of Northern Hemisphere forests to recent atmospheric CO 2 increases, highlighting the need for improved representation of the role of stomata in regulating forest–climate interactions. Bridging this gap between observations and theory as atmospheric CO 2 rises and climate change accelerates creates challenging opportunities for the next generation of physiologists to advance planetary ecology and climate science. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society .
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Duan, Honglang, Defu Wang, Xiaohua Wei, Guomin Huang, Houbao Fan, Shuangxi Zhou, Jianping Wu, Wenfei Liu, David T. Tissue, and Songze Wan. "The decoupling between gas exchange and water potential of Cinnamomum camphora seedlings during drought recovery and its relation to ABA accumulation in leaves." Journal of Plant Ecology 13, no. 6 (August 26, 2020): 683–92. http://dx.doi.org/10.1093/jpe/rtaa056.
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Abstract Aims Drought stress and the degree of drought severity are predicted to rise under highly variable patterns of precipitation due to climate change, while the capacity of trees to cope with drought recovery through physiological and biochemical adjustment remains unclear. We aimed to examine the coupling of physiology and biochemistry in trees during drought and the following recovery. Methods Potted seedlings of Cinnamomum camphora were grown under well watered conditions prior to the experimental drought stress, which was initiated by withholding water. Seedlings were rewatered following attainment of two drought severities: mild drought (stomatal closure) and moderate drought (ψxylem = −1.5 MPa). We measured leaf-level water potential, gas exchange (photosynthesis and stomatal conductance), abscisic acid (ABA), proline and non-structural carbohydrates (NSCs) concentrations in seedlings of C. camphora during drought and a 4-day recovery. Important Findings We found that drought severity largely determined physiological and biochemical responses and affected the rate of recovery. Stomatal closure occurred at the mild drought stress, accompanied with ABA accumulation in leaves and decline in water potential, while leaf proline accumulation and variable NSC were evident at the moderate drought stress. More severe drought stress led to delayed recovery of gas exchange, but it did not have significant effect on water potential recovery. The relationships of water potential and gas exchange differed during drought stress and post-drought recovery. There was tight coupling between water potential and gas exchange during drought, but not during rewatering due to high ABA accumulation in leaves, thereby delaying recovery of stomatal conductance. Our results demonstrate that ABA could be an important factor in delaying the recovery of stomatal conductance following rewatering and after water potential recovery of C. camphora. Furthermore, greater drought severity had significant impacts on the rate of recovery of tree physiology and biochemistry.
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Pezeshki, S. R., R. D. DeLaune, and W. H. Patrick Jr. "Gas exchange characteristics of bald cypress (Taxodiumdistichum L.): evaluation of responses to leaf aging, flooding, and salinity." Canadian Journal of Forest Research 16, no. 6 (December 1, 1986): 1394–97. http://dx.doi.org/10.1139/x86-250.
Full textAbstract:
Bald cypress (Taxodiumdistichum L.) seedlings were subjected to flooding with saline water containing 0 to 8 parts per thousand (137 mequiv. L−1 NaCl) under controlled environment conditions. Imposition of flooding and salinity stresses was designed to simulate the increase in submergence and salinity level which Louisiana's extensive cypress forests are currently experiencing as a result of rapid subsidence. The effect of flooding and salt water intrusion on subsequent stomatal behaviour and net photosynthesis for leaves developed before and after salt exposure were measured. Flooding and salinity resulted in a substantial decrease in stomatal conductance and net photosynthesis in both young and old leaves. Leaf aging did not significantly affect stomatal conductance and photosynthesis. Only plants flooded with freshwater and those flooded with low salinity concentration produced new leaves with improved stomatal conductance and net photosynthesis, which suggests some stomatal and photosynthetic acclimation to flooding and low salinity for bald cypress. Increase in salinity, however, caused more extensive impact and greater reductions of stomatal conductance and net photosynthesis in both leaf ages.
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Bunce, James. "Using New Gas Exchange Methods to Estimate Mesophyll Conductance and Non-stomatal Inhibition of Photosynthesis Caused by Water Deficits." HortScience 47, no. 6 (June 2012): 687–90. http://dx.doi.org/10.21273/hortsci.47.6.687.
Full textAbstract:
Soil water deficits remain one of the most important factors reducing the yield of crop plants and may become even more limiting with changes in the global climate and competition for fresh water resources. Soil water deficits reduce plant growth partly by reducing photosynthesis. However, it remains unclear how important non-stomatal factors are in limiting photosynthesis under moderate water stress and whether rising atmospheric carbon dioxide may alter which processes limit photosynthesis under water stress. The conductance to CO2 from the substomatal air space to the site of carboxylation inside chloroplasts in C3 plants is now termed mesophyll conductance. Because of the competition between CO2 and O2 for RuBisco, the carbon dioxide concentration at the chloroplast can be estimated from the O2 sensitivity of photosynthesis, providing a new method of estimating mesophyll conductance. It has also recently been realized that partial stomatal closure resulting from water stress can often be reversed by exposing leaves to low CO2. This provides a new means of assessing the non-stomatal component of the inhibition of photosynthesis by water stress. These methods were applied to four C3 species and revealed that mesophyll conductance decreased substantially with water stress in two of the four species and that reopening of stomata did not eliminate the reduction in photosynthesis caused by moderate water stress at either the current ambient or elevated CO2 concentrations.
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CRISPIM, BRUNO A., JULIANA C. V. SPÓSITO, ROSILDA M. MUSSURY, LEONARDO O. SENO, and ALEXÉIA B. GRISOLIA. "Effects of atmospheric pollutants on somatic and germ cells of Tradescantia pallida (Rose) D.R. HUNT cv. purpurea." Anais da Academia Brasileira de Ciências 86, no. 4 (December 2014): 1899–906. http://dx.doi.org/10.1590/0001-3765201420140338.
Full textAbstract:
Anatomical alterations in leaves and DNA damage in cells caused by the accumulation of atmospheric pollutants can be measured by epidermal leaf analyses and Tradescantia micronuclei assay with early pollen tetrad cells. The present study examined the feasibility of using somatic and germ cells of Tradescantia pallida for biomonitoring purposes in the city of Dourados, state of Mato Grosso do Sul (MS), Brazil. Stomatal, micronucleus and epidermal leaf analyses were performed, using standard methodologies, on plants growing at three locations during six different time periods. Tradescantia micronuclei data were analyzed using SAS 9.2 software package and stomatal data were analyzed using SANEST software. Analyses of stomatal characteristics and micronuclei examination in T. pallida were found to be an efficient tool for monitoring atmospheric pollution. The micronucleus assay suggested that the number of micronuclei in early pollen tetrad cells was related to the intensity of vehicular traffic. Increased number of epidermal cells and stomata and increased stomatal density observed at locations with greater vehicular traffic are likely physiological responses of those plants to the increased gas exchange in highly polluted environments.