Journal articles on the topic 'Xylem foundation'

Abstract Parasitic plants infect other plants by forming haustoria, specialized multicellular organs consisting of several cell types, each of which has unique morphological features and physiological roles associated with parasitism. Understanding the spatial organization of cell types is, therefore, of great importance in elucidating the functions of haustoria. Here, we report a three-dimensional (3-D) reconstruction of haustoria from two Orobanchaceae species, the obligate parasite Striga hermonthica infecting rice (Oryza sativa) and the facultative parasite Phtheirospermum japonicum infecting Arabidopsis (Arabidopsis thaliana). In addition, field-emission scanning electron microscopy observation revealed the presence of various cell types in haustoria. Our images reveal the spatial arrangements of multiple cell types inside haustoria and their interaction with host roots. The 3-D internal structures of haustoria highlight differences between the two parasites, particularly at the xylem connection site with the host. Our study provides cellular and structural insights into haustoria of S. hermonthica and P. japonicum and lays the foundation for understanding haustorium function.

The pine wood nematode Bursaphelenchus xylophilus is a destructive species affecting pine trees worldwide; however, the underlying mechanism leading to pathogenesis remains unclear. In this study, a B. xylophilus gene encoding thaumatin-like protein-1 (Bx-tlp-1) was silenced by RNA interference to clarify the relationship between the Bx-tlp-1 gene and pathogenicity. The in vitro knockdown of Bx-tlp-1 with double-stranded RNA (dsRNA) decreased B. xylophilus reproduction and pathogenicity. Treatments with dsRNA targeting Bx-tlp-1 decreased expression by 90%, with the silencing effect maintained even in the F3 offspring. Pine trees inoculated with B. xylophilus treated with Bx-tlp-1 dsRNA decreased the symptom of wilting, and the disease severity index was 56.7 at 30 days after inoculation. Additionally, analyses of the cavitation of intact pine stem samples by X-ray microtomography revealed that the xylem cavitation area of pine trees inoculated with B. xylophilus treated with Bx-tlp-1 dsRNA was 0.46 mm2 at 30 days after inoculation. Results from this study indicated that the silencing of Bx-tlp-1 has effects on B. xylophilus fitness. The data presented here provide the foundation for future analyses of Bx-tlp-1 functions related to B. xylophilus pathogenicity.

Although phytohormones are known to be important signal molecules involved in wood formation, their roles are still largely unclear. Here, Populus simonii × P. nigra seedlings were treated with different concentrations of exogenous phytohormones, indole-3-acetic acid (IAA), gibberellin (GA3), and brassinosteroid (BR), and the effects of phytohormones on growth were investigated. Next, 27 genes with known roles in wood formation were selected for qPCR analysis to determine tissue-specificity and timing of responses to phytohormone treatments. Compared to the control, most IAA, GA3, and BR concentrations significantly increased seedling height. Meanwhile, IAA induced significant seedling stem diameter and cellulose content increases that peaked at 3 and 30 mg·L−1, respectively. Significant increase in cellulose content was also observed in seedlings treated with 100 mg·L−1 GA3. Neither stem diameter nor cellulose content of seedlings were affected by BR treatment significantly, although slight effects were observed. Anatomical measurements demonstrated improved xylem, but not phloem, development in IAA- and BR-treated seedlings. Most gene expression patterns induced by IAA, GA3, and BR differed among tissues. Many IAA response genes were also regulated by GA3, while BR-induced transcription was weaker and slower in Populus than for IAA and GA3. These results reveal the roles played by phytohormones in plant growth and lay the foundation for exploring molecular regulatory mechanisms of wood formation in Populus.

Black carrots are characterized by a significant amount of anthocyanins, which are not only a good source of natural food colorant, but can also provide many health benefits to humans. In the present work, taproots of different carrot genotypes were used to identify the candidate genes related to anthocyanin synthesis, with particular a focus on R2R3MYB, bHLH transcription factors, and glutathione S-transferase gene (GST). The RNA-sequencing analysis (RNA-Seq) showed that DcMYB6 and DcMYB7 had a genotypic dependent expression and they are likely involved in the regulation of anthocyanin biosynthesis. They were specifically upregulated in solid black taproots, including both black phloem and xylem. DcbHLH3 (LOC108204485) was upregulated in all black samples compared with the orange ones. We also found that GST1 (LOC108205254) might be an important anthocyanin transporter, and its upregulated expression resulted in the increasing of vacuolar anthocyanin accumulation in black samples. Moreover, high performance liquid chromatographic (HPLC) analysis and liquid chromatography coupled to mass spectrometry (LC-MS) were used to identify the individual anthocyanin in the purple tissues of two carrot cultivars. The results showed that five main anthocyanin compounds and the most abundant anthocyanin were the same in different tissues, while the second-highest anthocyanin between three tissues was different, even in the same cultivar. In conclusion, this study combined anthocyanin profiles and comparative transcriptomic analysis to identify candidate genes involved in anthocyanin biosynthesis in carrots, thus providing a better foundation for improving anthocyanin accumulation in carrots as a source of colorants.

Phenylalanine ammonia lyase (PAL) plays an important role in the biosynthesis of secondary metabolites regulating plant growth response. To date, the evolutionary history of the PAL family in Rosaceae plants remains unclear. In this study, we identified 16 PAL homologous genes in five Rosaceae plants (Pyrus bretschneideri, Fragaria vesca, Prunus mume, Prunus persica, and Malus × domestica). We classified these PALs into three categories based on phylogenetic analysis, and all PALs were distributed on 13 chromosomes. We tracked gene duplication events and performed sliding window analysis. These results revealed the evolution of PALs in five Rosaceae plants. We predicted the promoter of the PbPALs by PLANT CARE online software, and found that the promoter region of both PbPAL1 and PbPAL3 have at least one AC element. The results of qRT-PCR analysis found that PbPAL1 and PbPAL2 were highly expressed in the stems and roots, while expression level of PbPAL3 was relatively low in different tissues. The expression of PbPAL1 and PbPAL2 increased firstly and then decreased at different developmental periods of pear fruit. Among them, the expression of PbPAL1 reached the highest level 55 days after flowering. Three PbPALs were induced by abiotic stress to varying degrees. We transfected PbPAL1 and PbPAL2 into Arabidopsis thaliana, which resulted in an increase in lignin content and thickening of the cell walls of intervascular fibres and xylem cells. In summary, this research laid a foundation for better understanding the molecular evolution of PALs in five Rosaceae plants. Furthermore, the present study revealed the role of PbPALs in lignin synthesis, and provided basic data for regulating lignin synthesis and stone cells development in pear plants.

The objective of this study was to develop a stem analysis data processing and computational algorithm and associated software suite that was (1) applicable to temperate and boreal forest tree species, (2) mathematically consistent with excurrent tree stem geometric and allometric principles, (3) compatible with data structures obtained using proprietary and non-proprietary imaging systems, and (4) executable on Windows®-based operating systems. Computationally, the suite denoted SAP (Stem Analysis Program), deployed sectional-specific formulae that were in accord with the following geometric assumptions: (1) stump section was treated as a solid of revolution resembling a cylinder; (2) sections between the stump and the tip were treated as a solid of revolution resembling a frustum of a cone for sections with continuous annual increments, otherwise treated as a cone; and (3) tip section was treated as a solid of revolution resembling a cone. The algorithm also corrected for the slant-based sectional length measurements using Pythagorean Theorem and eliminated the requirement to predict age-specific apex height development through the use of a linear interpolation procedure. Based on input data structures consisting of annual ring-width xylem sequences measured from cross-sectional disk samples acquired at multiple positions along the tree’s main stem, the suite produces a broad array of output, inclusive of radial and longitudinal ring-width sequences, apical growth increments, annual and cumulative sectional and cumulative volume production patterns, and historically reconstructed stem taper profiles. In total, the SAP creates six output data files for each tree analyzed: (1) input data reference summary (e.g., geometric mean ring-widths and resultant radii for each cross-section); (2) radial growth patterns for the cross-section sampled at breast-height (e.g., absolute and relative diameter and basal area growth estimates); (3) sectional (vertical) profiles of volume growth patterns (e.g., absolute and relative growth estimates within each section (bolt)); (4) cumulative volume growth patterns for the entire tree; (5) historical taper profile estimates (e.g., heights and diameters by year); and (6) texturally-labeled compendium of all output files generated. Additionally, real-time graphical output was produced for the purposes of data assessment and verification during the radial sequence data acquisition stage (e.g., graphical presentation of annual ring-width sequences by radii and disk, for use in validating input data structures and increment measurements derived from the imaging system), and interpreting growth and development patterns (e.g., vertical growth layer and specific volume increment profiles by age or year). The utility of the SAP suite was exemplified by processing WindendroTM-based annual ring-width xylem sequences obtained from cross-sectional disks extracted from a jack pine (Pinus banksiana Lamb.) tree via percent-height destructive stem analysis, and subsequently elucidating growth and developmental patterns within the context of silviculture treatment effects (thinning). The SAP suite provides the conceptual and logistical foundation for the continued deployment of the stem analysis approach in a wide range of investigations, including those examining the effect of naturogenic processes and anthropogenic influences on tree growth and development.

Brassinosteroids (BRs) are known to be essential regulators for wood formation in herbaceous plants and poplar, but their roles in secondary growth and xylem development are still not well-defined, especially in pines. Here, we treated Pinus massoniana seedlings with different concentrations of exogenous BRs, and assayed the effects on plant growth, xylem development, endogenous phytohormone contents and gene expression within stems. Application of exogenous BR resulted in improving development of xylem more than phloem, and promoting xylem development in a dosage-dependent manner in a certain concentration rage. Endogenous hormone determination showed that BR may interact with other phytohormones in regulating xylem development. RNA-seq analysis revealed that some conventional phenylpropanoid biosynthesis- or lignin synthesis-related genes were downregulated, but the lignin content was elevated, suggesting that new lignin synthesis pathways or other cell wall components should be activated by BR treatment in P. massoniana. The results presented here reveal the foundational role of BRs in regulating plant secondary growth, and provide the basis for understanding molecular mechanisms of xylem development in P. massoniana.

The current infrafamilial taxonomy of the Iridaceae recognizes four subfamilies; Isophysidoideae (1: 1); Nivenioideae (6: ca. 92), Iridoideae (29: 890), and Crocoideae (29: 1032). Phylogenetic analyses of sequences of five plastid DNA regions, rbcL, rps4, trnL–F, matK, and rps16, confirm most aspects of this classification and the evolutionary patterns that they imply, importantly the sisiter relationship of Isophysidoideae to the remainder of the family and the monophyly of Iridoideae. Subfamily Nivenioideae is, however, paraphyletic; Crocoideae is consistently found nested within it, sister to the core Nivenioideae, the woody Klattia, Nivenia, and Witsenia. This clade is sister to Aristea, which in turn is sister to the Madagascan Geosiris, and then to the Australasian Patersonia. We treat Aristea, Geosiris, and Patersonia as separate subfamilies, Aristeoideae and the new Geosiridaceae and Patersonioideae, rendering Nivenioideae and Crocoideae monophyletic. The alternative, uniting a widely circumscribed Nivenioideae and Crocoideae, seems undesirable because Nivenioideae have none of the numerous synapomorphies of Crocoideae, and that subfamily includes more than half the total species of Iridaceae. Main synapomorphies of Crocoideae are: pollen operculate; exine perforate; ovule campylotropous; root xylem vessels with simple perforations; rootstock a corm; inflorescence usually a spike; plants deciduous. Four more derived features of Crocoideae are shared only with core Nivenioideae: flowers long-lived; perianth tube well developed; flowers sessile; and septal nectaries present. The genera of the latter subfamily are evergreen shrubs, have monocot-type secondary growth, tangentially flattened seeds, and the inflorescence unit is a binate rhipidium. The latter feature unites core Nivenioideae with Aristea, Geosiris, and Patersonia, which have fugaceous flowers and, with few exceptions, a blue perianth. Molecular-based phylogenetic trees using sequences from five plastid DNA regions now show discrete generic clusters within Crocoideae and Iridoideae, the foundation for the tribal classification. The five tribe classification of Iridoideae, initially based on morphological characters and subsequently supported by a four plastid DNA region sequence analysis, continues to receive support using additional DNA sequences. Application of molecular clock techniques to our phylogeny indicates that the Iridaceae differentiated in the late Cretaceous and diverged from the next most closely related family, Doryanthaceae circa 82 mya, thus during the Campanian. The Tasmanian Isophysis is the only extant member of the clade sister to the remainder of the Iridaceae, from which it may have diverged 66 mya, in the Maastrichtian. The generic phylogeny shows the proximal clades of the family are all Australasian, which corroborates past hypotheses that the Iridaceae originated in Antarctica-Australasia, although its subsequent radiation occurred elsewhere, notably in southern Africa and temperate and highland South America at the end of the Eocene or later.

The response of the shallow portion of the ground (vadose zone) and of earth structures is affected by the interaction with the atmosphere. Rainwater infiltration and evapotranspiration affect the stability of man-made and natural slopes and cause shallow foundations and embankments to settle and heave. Very frequently, the ground surface is covered by vegetation and, as a result, transpiration plays a major role in ground-atmosphere interaction. The soil, the plant, and the atmosphere form a continuous hydraulic system, which is referred to as Soil-Plant-Atmosphere Continuum (SPAC). The SPAC actually represents the ‘boundary condition’ of the geotechnical water flow problem. Water flow in soil and plant takes place because of gradients in hydraulic head triggered by the negative water pressure (water tension) generated in the leaf stomata. To study the response of the SPAC, (negative) water pressure needs to be measured not only in the soil but also in the plant. The paper presents a novel technique to measure the xylem water pressure based on the use of the High-Capacity Tensiometer (HCT), which is benchmarked against conventional techniques for xylem water pressure measurements, i.e. the Pressure Chamber (PC) and the Thermocouple Psychrometer (TP).

Abstract Ralstonia solanacearum is a bacterial vascular pathogen causing devastating bacterial wilt. In the field, resistance against this pathogen is quantitative and is available for breeders only in tomato and eggplant. To understand the basis of resistance to R. solanacearum in tomato, we investigated the spatio-temporal dynamics of bacterial colonization using non-invasive live monitoring techniques coupled to grafting of susceptible and resistant varieties. We found four ‘bottlenecks’ that limit the bacterium in resistant tomato: root colonization, vertical movement from roots to shoots, circular vascular bundle invasion, and radial apoplastic spread in the cortex. Radial invasion of cortical extracellular spaces occurred mostly at late disease stages but was observed throughout plant infection. This study shows that resistance is expressed in both root and shoot tissues, and highlights the importance of structural constraints to bacterial spread as a resistance mechanism. It also shows that R. solanacearum is not only a vascular pathogen but spreads out of the xylem, occupying the plant apoplast niche. Our work will help elucidate the complex genetic determinants of resistance, setting the foundations to decipher the molecular mechanisms that limit pathogen colonization, which may provide new precision tools to fight bacterial wilt in the field.

Botrytis cinerea infection of wine grapes can result in a variety of symptoms. The most common symptom is botrytis bunch rot (BBR), where infected berries rot and shrivel, and eventually produce fungal sporulation. Another symptom is slip skin, where the skins of infected ripe berries slide easily from the pulp. It is hypothesised that a reduction in osmotic potential in grape berries due to late-season rainfall leads to slip skin symptom development. Hyphal growth of B. cinerea on osmotically adjusted agar was inhibited at osmotic potentials associated with near-ripe berries. Vine sheltering was used in a research vineyard to manipulate rainfall artificially and to alter berry sugar content in Vitis vinifera Sauvignon blanc vines, with the aim of increasing osmotic potential and altering symptom expression. Both BBR and slip skin symptoms were affected by the various sheltering conditions, with sheltered vines having lower BBR and higher slip skin at harvest. REFERENCES Becker T, Grimm E, Knoche M 2012. Substantial water uptake into detached grape berries occurs through the stem surface. Australian Journal of Grape and Wine Research 18: 109-114. https://doi.org/10.1111/j.1755-0238.2011.00177.x Beever RE, Laracy EP 1986. Osmotic adjustment in the filamentous fungus Aspergillus nidulans. Journal of Bacteriology 168: 1358-1365. https://doi.org/10.1128/jb.168.3.1358-1365.1986 Beresford RM, Hill GN 2008. Botrytis control without fungicide residues - is it just a load of rot? New Zealand Winegrower 12: 104-106. Beresford RM, Evans KJ, Wood PN, Mundy DC 2006. Disease assessment and epidemic monitoring methodology for bunch rot (Botrytis cinerea) in grapevines. New Zealand Plant Protection 59: 355-360. Bondada BR, Matthews MA, Shackel KA 2005. Functional xylem in the post-véraison grape berry. Journal of Experimental Botany 56: 2949-2957. https://doi.org/10.1093/jxb/eri291 Choat B, Gambetta GA, Shackel KA, Matthews MA 2009. Vascular function in grape berries across development and its relevance to apparent hydraulic isolation. Plant Physiology 151: 1677-1687. https://doi.org/10.1104/pp.109.143172 Clarke SJ, Hardie WJ, Rogiers SY 2010. Changes in susceptibility of grape berries to splitting are related to impaired osmotic water uptake associated with losses in cell vitality. Australian Journal of Grape and Wine Research 16: 469-476. https://doi.org/10.1111/j.1755-0238.2010.00108.x Diakou P, Moing A, Svanella L, Ollat N, Rolin DB, Gaudillere M, Gaudillere JP 1997. Biochemical comparison of two grape varieties differing in juice acidity. Australian Journal of Grape and Wine Research 3: 1-10. https://doi.org/10.1111/j.1755-0238.1997.tb00122.x Grolemund G, Wickham H 2011. Dates and times made easy with lubridate. 2011 40: 25. Harris RF 1981. Effect of water potential on microbial growth and activity. In: Parr JF, Gardner WR, Elliott LF eds. Water Potential Relations in Soil Microbiology. SSSA Special Publication. Soil Science Society of America. Pp. 23-95. Hill GN, Beresford RM, Evans KJ 2010. Tools for accurate assessment of botrytis bunch rot (Botrytis cinerea) on wine grapes. New Zealand Plant Protection 63: 174-181. Hill GN, Evans KJ, Beresford RM 2014a. Use of nitrate non-utilising (nit) mutants to determine phenological stages at which Botrytis cinerea infects wine grapes causing botrytis bunch rot. Plant Pathology 63: 1316-1325. https://doi.org/10.1111/ppa.12225 Hill GN, Evans KJ, Beresford RM, Dambergs RG 2014b. Comparison of methods for the quantification of botrytis bunch rot in white wine grapes. Australian Journal of Grape and Wine Research 20: 432—441. https://doi.org/10.1111/ajgw.12101 Keller M, Smith JP, Bondada BR 2006. Ripening grape berries remain hydraulically connected to the shoot. Journal of Experimental Botany 57: 2577-2587. https://doi.org/10.1093/jxb/erl020 Loschiavo A, Scholefield P, Morrison J, Ferris M 2010. The cost of pests and diseases to the Australian winegrape industry. Australian Viticulture 14: 15-19. McCarthy MG, Coombe BG 1999. Is weight loss in ripening grape berries cv. Shiraz caused by impeded phloem transport? Australian Journal of Grape and Wine Research 5: 17-21. https://doi.org/10.1111/j.1755-0238.1999.tb00146.x Mendiburu Fd 2016. agricolae: Statistical Procedures for Agricultural Research. https://CRAN.R-project.org/package=agricolae. Mundy DC, Beresford RM 2007. Susceptibility of grapes to Botrytis cinerea in relation to berry nitrogen and sugar concentration. New Zealand Plant Protection 60: 123-127. Nelson KE 1956. The effect of Botrytis infection on the tissue of Tokay grapes. Phytopathology 46: 223-229. NIWA 2017. Mean monthly rainfall (mm). https://www.niwa.co.nz/education-and-training/schools/resources/climate/meanrain (05-05-2017). Pezet R, Viret O, Perret C, Tabacchi R 2003. Latency of Botrytis cinerea Pers.: Fr. and biochemical studies during growth and ripening of two grape berry cultivars, respectively susceptible and resistant to grey mould. Journal of Phytopathology 151: 208-214. https://doi.org/10.1046/j.1439-0434.2003.00707.x R Core Team 2016. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/. R Studio Team 2016. RStudio: Integrated Development for R. RStudio, Inc., Boston, MA. http://www.rstudio.com/. Rogiers SY, Smith JA, White R, Keller M, Holzapfel BP, Virgona JM 2001. Vascular function in berries of Vitis vinifera (L) cv. Shiraz. Australian Journal of Grape and Wine Research 7: 47-51. https://doi.org/10.1111/j.1755-0238.2001.tb00193.x Schindelin J, Arganda-Carreras I, Frise E, Kaynig V, Longair M, Pietzsch T, Preibisch S, Rueden C, Saalfeld S, Schmid B, Tinevez J-Y, White DJ, Hartenstein V, Eliceiri K, Tomancak P, Cardona A 2012. Fiji: an open-source platform for biological-image analysis. Nature Methods 9: 676-682. https://doi.org/10.1038/nmeth.2019 Smart R, Robinson M 1991. Sunlight into Wine. Winetitles, Adelaide, Australia. Taiz L, Zeiger E 1998. Plant Physiology. Sinauer Associates, Sunderland, MA, USA. Tyerman SD, Tilbrook J, Pardo C, Kotula L, Sullivan W, Steudle E 2004. Direct measurement of hydraulic properties in developing berries of Vitis vinifera L. cv Shiraz and Chardonnay. Australian Journal of Grape and Wine Research 10: 170-181. https://doi.org/10.1111/j.1755-0238.2004.tb00020.x Whiting EC, Rizzo DM 1999. Effect of water potential on radial colony growth of Armillaria mellea and A. gallica isolates in culture. Mycologia 91: 627-635. https://doi.org/10.2307/3761248 Wickham H 2009. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York. Wickham H 2016. tidyverse: Easily Install and Load 'Tidyverse' Packages. https://CRAN.R-project.org/package=tidyverse. Wickham H, Bryan J 2017. readxl: Read Excel Files. https://CRAN.R-project.org/package=readxl. Wilcox WF, Gubler WD, Uyemoto JK 2015. Compendium of Grape Diseases, Disorders, and Pests: Second Edition. APS Press, St Paul, MN, USA.

Enormous distinctions of the stem structure and cell types between gymnosperms and angiosperms tree species are expected to cause quite different wood physical and mechanical attributes, however, the molecular mechanisms underlying the differing wood morphology are still unclear. In this study, we compared the transcriptomes obtained by RNA-Seq between Populus alba × P. glandulosa clone 84K, and Larix kaempferi (Lamb.) Carr trees. Available genome resource served as reference for P. alba × P. glandulosa and the Iso-Seq results of a three-tissues mixture (xylem, phloem, and leaf) were used as the reference for L. kaempferi to compare the xylem-specifically expressed genes and their alternative splicing model. Through screening, we obtained 13,907 xylem-specifically expressed genes (5,954 up-regulated, 7,953 down-regulated) in the xylem of P. alba × P. glandulosa, and 2,596 xylem-specifically expressed genes (1,648 up-regulated, 948 down-regulated) in the xylem of L. kaempferi. From the GO and KEGG analyses, some genes associated with two wood formation-related pathways, namely those for phenylpropanoid biosynthesis, and starch and sucrose metabolism, were successfully screened. Then the distributions and gene expression models between P. alba × P. glandulosa and L. kaempferi in those pathways were compared, which suggested differential wood formation processes between the angiosperm and gymnosperm trees. Furthermore, a Weight Gene Co-expression Network Analysis (WGCNA) for total xylem-specifically expressed genes in two species was conducted, from which wood formation-related modules were selected to build a co-expression network for the two tree species. The genes within this co-expression network showed different co-expression relationships between the angiosperm and gymnosperm woody species. Comparing the alternative splicing events for wood formation-related genes suggests a different post-transcriptional regulation process exists between the angiosperm and gymnosperm trees. Our research thus provides the foundation for the in-depth investigation of different wood formation mechanisms of angiosperm and gymnosperm species.

Xylem sap, belonging to the plant apoplast, not only provides plant tissues with inorganic and organic substances but also facilitates communication between the roots and the leaves and coordinates their development. This study investigated the effects of potassium (K) deficiency on the morphology and the physiology of cotton seedlings as well as pH, mineral nutrient contents, and metabolites of xylem sap. In particular, we compared changes in root–shoot communication under low K (LK) and normal K (NK, control) levels. Compared to control, LK stress significantly decreased seedling biomass (leaf, stem, and root dry weight; stem and root length; root surface area and root volume) and the levels of K, Na (sodium), Mg (magnesium), Fe (iron), and Zn (zinc) in xylem sap. A total of 82 metabolites in sap analyzed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) showed significant differences between the two conditions; among these, 38 were up-regulated more than 2-fold, while the others were down-regulated less than 0.5-fold. In particular, several metabolites found in the cell membrane including three cholines (glycerophosphatecholine, 2-hexenylcholine, and caproylcholine) and desglucocoroloside and others such as malondialdehyde, α-amino acids and derivatives, sucrose, and sugar alcohol significantly increased under LK stress, indicating that cell membranes were damaged and protein metabolism was abnormal. It is worth noting that glycerophosphocholine was up-regulated 29-fold under LK stress, indicating that it can be used as an important signal of root–shoot communication. Furthermore, in pathway analyses, 26 metabolites were matched to Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways; L-aspartic acid, which was associated with 10 KEGG pathways, was the most involved metabolite. Overall, K deficiency reduced the antioxidant capacity of cotton seedlings and led to a metabolic disorder including elevated levels of primary metabolites and inhibited production of secondary metabolites. This eventually resulted in decreased biomass of cotton seedlings under LK stress. This study lays a solid foundation for further research on targeted metabolites and signal substances in the xylem sap of cotton plants exposed to K deficiency.

Despite the substantial economic impact of Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff) on legume productions worldwide, the genetic basis of its pathogenicity and potential host association is poorly understood. The production of high-quality reference genome assemblies of Cff strains associated with different hosts sheds light on the genetic basis of its pathogenic variability and host association. Moreover, the study of recent outbreaks of bacterial wilt and microevolution of the pathogen in Australia requires access to high-quality, reference genomes that are sufficiently closely related to the population being studied within Australia. We provide the first genome assemblies of Cff strains associated with mungbean and soybean, which revealed high variability in their plasmid composition. The analysis of Cff genomes revealed an extensive suite of carbohydrate-active enzymes potentially associated with pathogenicity, including four carbohydrate esterases, 50 glycoside hydrolases, 23 glycosyl transferases, and a polysaccharide lyase. We also identified 11 serine peptidases, three of which were located within a linear plasmid, pCff119. These high-quality assemblies and annotations will provide a foundation for population genomics studies of Cff in Australia and for answering fundamental questions regarding pathogenicity factors and adaptation of Cff to various hosts worldwide, and, at a broader scale, contribute to unravelling genomic features of Gram-positive, xylem-inhabiting bacterial pathogens.

Abstract Background Class III peroxidases (POD) proteins are widely present in the plant kingdom that are involved in a broad range of physiological processes including stress responses and lignin polymerization throughout the plant life cycle. At present, POD genes have been studied in Arabidopsis, rice, poplar, maize and Chinese pear, but there are no reports on the identification and function of POD gene family in Betula pendula. Results We identified 90 nonredundant POD genes in Betula pendula. (designated BpPODs). According to phylogenetic relationships, these POD genes were classified into 12 groups. The BpPODs are distributed in different numbers on the 14 chromosomes, and some BpPODs were located sequentially in tandem on chromosomes. In addition, we analyzed the conserved domains of BpPOD proteins and found that they contain highly conserved motifs. We also investigated their expression patterns in different tissues, the results showed that some BpPODs might play an important role in xylem, leaf, root and flower. Furthermore, under low temperature conditions, some BpPODs showed different expression patterns at different times. Conclusions The research on the structure and function of the POD genes in Betula pendula plays a very important role in understanding the growth and development process and the molecular mechanism of stress resistance. These results lay the theoretical foundation for the genetic improvement of Betula pendula.

AbstractPine wilt disease was first discovered in Dongtang town, Liaoning Province, China, in 2017. Monochamus saltuarius Gebler is a new vector of pinewood nematode and the only known vector in Liaoning Province. The biology of this pest has not been reported thus far; therefore, it is necessary to study its life history. During 2018 and 2019, we collected 138 and 491 adult M. saltuarius beetles, respectively, to analyze their eclosion from larva to adult stage. In mid-March, overwintering larvae began to feed (on xylem) and seek nutrition in preparation for pupation and eclosion. The adults began to appear in mid-April, and the population reached its peak in late May. The life span of the adults was 28–76 days. After approximately 1 week of supplemental nutrition (feeding on twigs), adults began to mate and lay eggs. The egg stage of M. saltuarius lasted 4–8 days. The larvae in Dongtang town have 4 instars and overwinter in tunnels as 3rd–4th instars. The 1st-instar stage lasted 3–9 days, the 2nd-instar stage lasted 11–23 days, the 3rd-instar stage lasted 30–130 days, and the 4th-instar stage lasted 44–180 days. The pupal stage lasted 7–12 days, and the life span of the adults was 28–76 days. In this study we systematically monitored the life history of M. saltuarius for the first time. Our objective was to lay a foundation for improving control of this pinewood nematode vector.

AbstractPrunus mume (also known as Mei) is an important ornamental plant that is popular with Asians. The weeping trait in P. mume has attracted the attention of researchers for its high ornamental value. However, the formation of the weeping trait of woody plants is a complex process and the molecular basis of weeping stem development is unclear. Here, the morphological and histochemical characteristics and transcriptome profiles of upright and weeping stems from P. mume were studied. Significant alterations in the histochemical characteristics of upright and weeping stems were observed, and the absence of phloem fibres and less xylem in weeping stems might be responsible for their inability to resist gravity and to grow downward. Transcriptome analysis showed that differentially expressed genes (DEGs) were enriched in phenylpropanoid biosynthesis and phytohormone signal transduction pathways. To investigate the differential responses to hormones, upright and weeping stems were treated with IAA (auxin) and GA3 (gibberellin A3), respectively, and the results revealed that weeping stems had a weaker IAA response ability and reduced upward bending angles than upright stems. On the contrary, weeping stems had increased upward bending angles than upright stems with GA3 treatment. Compared to upright stems, interestingly, DEGs associated with diterpenoid biosynthesis and phenylpropanoid biosynthesis were significantly enriched after being treated with IAA, and expression levels of genes associated with phenylpropanoid biosynthesis, ABC transporters, glycosylphosphatidylinositol (GPI)—anchor biosynthesis were altered after being treated with GA3 in weeping stems. Those results reveal that multiple molecular mechanisms regulate the formation of weeping trait in P. mume, which lays a theoretical foundation for the cultivation of new varieties.

AbstractPaeoniaceae is an abundant germplasm resource with significant medicinal values in China, the principal medicinal components of which include paeoniflorin and paeonol. These compounds are typically obtained from air-dried root samples, which the use of freeze-drying as an alternative method has not been tested. Additionally, the presence of these two compounds in various wild Paeoniaceae species has not been previously explored, nor have the differences between various plant organs been fully evaluated. Here, freeze-drying and air-drying methods were compared to assess the changes in paeoniflorin and paeonol in root samples using ultra-performance liquid chromatography-mass spectrometer. The contents of these compounds in the roots, leaves, stems, and petals were then tested in freeze-dried materials. We also quantitatively detected the paeoniflorin and paeonol contents in the roots of 14 species collected from 20 natural habitats. Results indicated that the paeoniflorin content decreased under air-drying in comparison to freeze-drying, while the opposite trend was observed for paeonol. Our findings also demonstrated that the root xylem of species in Section Moutan, particularly Paeonia ostii, contains considerable paeonol and paeoniflorin and should thus be fully utilized as a medicinal resource. Furthermore, paeonol was mainly detected in the roots, while paeoniflorin was widely distributed in different organs; the highest content was in the leaf at the budding stage, suggesting that the leaves should be developed as a new paeoniflorin resource. Paeoniflorin contents were also found to be higher at earlier development stages. Based on the standards of the Chinese Pharmacopoeia, five species of Section Moutan and six species of Section Paeonia could be used as potential traditional Chinese medicinal resources. These findings of this study enhance our understanding of these two medicinal compounds and provide a foundation for the further development and utilization of Paeoniaceae as medicinal plant resources.

Abstract Objectives American adolescents have a nutrient-poor diet pattern, which is particularly high in added sugars, putting them at risk for obesity and type 2 diabetes (T2D). We aimed to assess dietary intake of added sugars in adolescents and relationships with glycemia and body mass index (BMI). Methods Cross-sectional, baseline measures were obtained from an ongoing, randomized controlled behavioral intervention to prevent adolescent T2D. Participants, using the Technology Assisted Dietary Assessment system (TADA), created a mobile, imaged-based, four-day food record which the Nutrition Data System for Research (NDSR, University of Minnesota, Minneapolis, MN) analyzed. Glucose dynamics were measured at fasting and during an oral glucose tolerance test (OGTT), using point of care instruments (DCA Analyzer, Siemens Medical Solutions, Malvern, PA; YSI Analyzers, Xylem Inc., Yellow Springs, OH). High added sugar intake was defined as consuming above the recommendation of 10% of calories from the US Dietary Guidelines. Independent sample T-tests assessed the differences between groups consuming high versus recommended amounts of added sugars. Values are expressed as mean ± standard deviation. Results Thirty-one adolescents, ages 15.5 ± 2.4 years, were screened. The sample was composed of 12 boys and 19 girls, and 45% had prediabetes. The BMI of the sample was 34.3 ± 6.8 kg/m2 with no differences between normal status and prediabetes groups. Similarly, normal status (11.2 ± 4.6%) and prediabetes (11.3 ± 5.0%) groups each consumed excess amounts of added sugars with no differences between groups. There were no significant differences between glycated hemoglobin (HbA1c, 5.5 ± 0.5% and 5.3 ± 0.2%), 2 hour glucose concentrations (125.4 ± 28.7 mg/dL and 111.9 ± 22.0 mg/dL), or BMI (33.9 ± 6.0 kg/m2 and 34.9 ± 8.2 kg/m2) between the groups with high versus recommended intakes of added sugar, respectively. The fasting plasma glucose concentrations in the group with high intakes of added sugar tended to be higher compared to the group with recommended intake of added sugar (94.6 ± 5.7 mg/dL versus 90.8 ± 5.1 mg/dL, P = 0.095). Conclusions Fasting glucose may be higher in adolescents consuming excess compared to recommended amounts of added sugars. This research highlights the need for additional research to clarify the metabolic consequences of high amounts of added sugars in the diets of adolescents with obesity and a risk for developing type 2 diabetes. Funding Sources McKinley Foundation, Indiana CTSI Project Development Team UL1TR002529.