Academic literature on the topic 'Arid regions plants Diseases and pests'

The creation of modern green spaces should be based on the selection of a sustainable assortment. Resistance is evaluated on the basis of a number of physiological indicators. Preliminary testing is of particular value for industrial regions with difficult climatic conditions. The purpose of this study was to study the resistance of 4 species of poplars to drought, winter conditions, the effects of diseases and pests, and atmospheric pollution. Resistance assessment was carried out for the species Populus alba, Populus balsamifera, Populus canadensis, Populus nigra, covering the period from 2015 to 2019. The results of visual observations showed that all species of poplars have high winter resistance — 4–5 points. Maximum winter resistance is noted for white poplar, minimum — for canadian poplar. The gas stability of poplars is estimated at 3–5 points. The greatest stability is noted in balsamic poplar, the minimum — in canadian poplar. Drought resistance among poplar species is estimated at 3–4 points. White and canadian poplar showed the least resistance to drought, while canadian poplar showed the maximum. Estimated scores of resistance to diseases and pests were 4–5 points, the highest indicators were noted for balsamic poplar, the minimum — for black poplar. On the basis of the identified indicators, the directions of poplar use in green construction are proposed.

Tomato crops are among the most important vegetables cultivated worldwide, Mexico being one of the major producing countries. Large quantity of this crop is found in states belonging to the arid northwest of the country; the adaptation of these regions to vegetable production has been significant with the support of agricultural technology due to the use of protective structures for plants, such as greenhouses and shaded mesh. However, pests and diseases are a major biotic factor that significantly reduces production. There are more than 200 diseases associated with the nightshade of various etiologies. The process of identifying the cause of a disease in plants is called diagnosis. The diagnosis of plant diseases has been described as an art and a science; it requires scientific knowledge of plant pathology and related disciplines. Effective disease control requires making the best possible decisions to reduce the risk of serious production losses. Control strategies based on prevention of disease and methods that slow the spread of such diseases. Therefore, proper management of diseases affecting the tomato crop, knowledge and understanding of the diagnosis and its infectious cycle is vital and to establish effective control measures.

Abstract. Many methods of protected agriculture are used to modify the growing environment of plants. Ideally, plant production would take place in regions that do not require protective structures, regions that present ideal temperatures, no harsh extremes, and sufficient but not excess precipitation. This is not the case however, as most countries, save for a select few, require various forms of controlled environment agriculture to protect crops against climatic and environmental extremes. Although the greenhouse industry has developed vast amounts of technology for the temperate climate regions of our planet, much remains to be improved in terms of protected agriculture in the more extreme climates. Tropical, arid, polar and urban locations offer contrasting environments that present various challenges for plant growth. Some challenges are specific to each location, while others are common across them. Tropical and arid climates offer high solar radiation, but present harsh temperature and relative humidity conditions. Most protected agriculture structures are relatively open in nature to ventilate and discharge heat, but are susceptible to pests and diseases. On the other hand, polar climates and urban environments often lack solar radiation and require a high level of control of the air quality. The structures used in these environments are relatively enclosed to entrap heat (polar) and to make efficient use of space. The sustainability of available technologies and energy efficiency are important themes present in all discussed climates and environments. Protected agriculture technologies offer solutions to growers in locations with extreme climates wishing to produce high yields of high quality crop, and this article presents a review of the existing challenges and of the advancements made in this field. Keywords: Arid climate greenhouse, Evaporative cooling, Natural ventilation, Protected agriculture, Tropical climate greenhouse, Urban agriculture, Vertical farming.

Currently, there is a certain tendency in Russia to increase the acreage occupied by sorghum crops. According to the Federal State Statistics Service, 90.0 thousand hectares of sorghum for grain were sown in 2021, and by 2022 the acreage under sorghum increased by 129.0%, which amounted to 116.0 thousand hectares. The choice of this crop, of course, is determined by its tolerance to soils, high drought resistance, the ability to withstand extreme positive temperatures in arid climatic conditions of Russia without loss of yield and grain quality, which allows the crop to be cultivated in many regions of the Russian Federation. However, the increase in the area of sowing is restrained by insufficient attention of production workers to the requirements of agricultural technology, biological features of culture. Sorghum has a complex of protective properties in relation to diseases, pests and unfavorable conditions: the presence of wax plaque, the content of alkaloids, silica and other substances that provide a high degree of resistance of this culture. Permanent sowing on the same areas leads to the accumulation of a large number of pathogens. Obtaining healthy seed material is one of the main agronomic requirements in ensuring high and stable yields. In this regard, the dependence of the initial growth indicators on the germination of sorghum seeds exposed to pathogens has been analyzed. The degree of damage to sorghum plants by smut diseases has been revealed. Keywords: SORGHUM, FUNGAL DISEASES, SEEDS, PATHOGEN, INFECTION

Calotropis procera (Aiton) Dryand (commonly known as the apple of sodom, calotrope, and giant milkweed) is an evergreen, perennial shrub of the Apocynaceae family, and is mainly found in arid and semi-arid regions. Previous studies have established the toxic effects of Calotropis procera (C. procera) (Aiton). Its extract is used as one of the vital alternatives to pesticides due to its effective impacts on several pathogens and to combat insect pests that cause severe damage to several crops, but so far, its effects on combating Fusarium oxysporum f. sp. lycopersici (FOL) have not yet been evaluated. Therefore, the current study focuses on evaluating the effects of the aqueous extract of this plant on FOL by studying physicochemical indicators. In Saudi Arabia and many other countries, such disease is considered as one of the critical factors affecting tomato growth and production. For the control of Fusarium wilt disease (Fwd), many strategies have been developed, but are limited in their use. Ten isolates of the pathogens were obtained from diseased tomato plants. These isolates were able to exhibit symptoms of tomato wilt, and they varied in their virulence. Isolate No. 5 caused the highest severity of the disease (73%). According to these results, we used this isolate in the following experiment, which was identified by ITS sequences as F. oxysporum f. sp. lycopersici. Following intensive screening studies, we selected aqueous plant extract of C. procera to study its effectiveness against Fwd of tomato plants and their antifungal activity or induce systemic resistance in plants. All concentrations of C. procera extracts suppressed growth of the pathogen. The highest reduction of mycelia growth was obtained by aqueous extract at 15%, it reduced the pathogen growth to 70.2%, relative to the control. In greenhouse conditions, the aqueous C. procera extract at 5, 10, and 15% significantly reduced Fwd of the tomato compared to the infected control (52.01, 69.86, and 83.6%, respectively). The use of aqueous C. procera extract at 5, 10, and 15% significantly enhanced the fresh and dry weight of tomato plants (g plant−1) compared to inoculated plants (for fresh weight: 50, 66.6, and 86.6 and for dry weight: 60, 100, and 120%, respectively). Total phenols and flavonoids as well as antioxidant enzymes were increased in inoculated or non-inoculated tomato plants after being treated with aqueous extracts of C. procera.

Arid conditions in Central Ciscaucasia caused a shortage of green fodder for animal husbandry. In the current circumstances, new sorghum-sudan hybrids creation and introduction into production are of great importance. The aim of the research is twofold: to assess green mass, hay and grain productivity and quality; to determine the main biomorphological characteristics and level of heterosis of the new sorghum-sudan hybrid ‘Gvardeets’. The experiments were carried out in competitive and environmental testing. In the Novgorod Oblast, the new hybrid provided 43.0 t/ha of green mass; the same indicator in the Altai FASC comprised 42.1 t/ha exceeding standard hybrid ‘Navigator’ by 2.6 and 0.9 t/ha, respectively. The data were obtained in a competitive test by methods of field and laboratory experiments, as well as environmental testing in various regions of Russia. On average for 2015–2020, in the conditions of the Stavropol Territory, the new hybrid provided 53.87 t/ha of green and 11.55 t/ha of dry matter exceeding standard hybrid ‘Navigator’ by 5.03 and 1.26 t/ha or 10.3 and 12.2%, respectively. ‘Gvardeets’ is a mid-ripening hybrid. The first mowing can be carried out in the booting phase or at the end of June/first half of July, the second one – in the second half of August. Furthermore, in moderately warm and humid summers, it is possible to obtain the third mowing in late September/early October. The new hybrid ‘Gvardeets’ has a high rate of initial plants growth on the 30th day of vegetation (80 cm), as well as a high content of leaves in the green mass (34.7 %). The content of protein in dry matter is 11.8 %, fat – 1.9 %, fiber – 30.9%, ash – 6.3 %. One kilogram of new combination feed contains 0.67 feed units, 70 g of digestible protein, 31.9 g of sugar, 81.2 mg of carotene. The provision of one feed unit with digestible protein is 123 g. There is 8.59 MJ/kg of exchange energy, which is better than that of the standard hybrid ‘Navigator’. The stems of ‘Gvardeets’ plants have a juicy core; plants are resistant to drought, lodging, pests and diseases. The parental forms of the hybrid (‘Zersta 90C’ x ‘Sputnitsa’) are distinguished by a high combinational ability and provide a level of true heterosis of the yield of green mass in the amount of 20.81 t/ha (62.9%). The new sorghum-sudan hybrid ‘Gvardeets’ has been included in the State Register of Breeding Achievements of the Russian Federation since 2021 in the North Caucasus, Lower Volga, Central Black Earth and West Siberian regions.

The Federal Scientific Center for Agroecology of the Russian Academy of Sciences (formerly the all-Russian research Institute of agroforestry) is one of the only scientific institutions in Russia that solves the problems of protecting soils from degradation and desertification and increasing their fertility by using the protective properties of adapted wood, shrub and herbaceous vegetation. Continuous use in research and obtaining ecological, economic and social benefits from the bioresources of economically valuable trees and shrubs of their own selection are key elements for developing a methodology for the innovative development of modern green technologies, including nursery production in the arid region of Russia. The Federal Scientific Center of Agroecology of the Russian Academy of Sciences has considerable experience in creating and implementing the results of scientific work aimed at achieving high and sustainable indicators in the forest and agro-industrial complex. It is shown that the creation of selection and seed centre has sufficient space dendrological collections, mother cells, of commercially valuable ornamental plantations, agroforestry, fruit, pasture trees, shrubs (Samara, Volgograd, Oryol, Astrakhan regions, Altai, Stavropol Krai), nursery and greenhouse complex (Nizhnevolzhsky station on selection of tree species), and land – more than 60 thousand hectares of land. Over the years, many years of ecological and experimental monitoring have been conducted on the introduction, selection, protection of plants from pests and diseases, varietal, seed and nursery production of economically important tree species in arid conditions. It is established that the unique capabilities of adaptive selection of a range of commercially valuable trees and shrubs (660 species, forms, hybrids and varieties) to meet changing conditions and requirements provide a collection funds of woody plants FSC of Agroecology Russian Academy of Sciences and its branches (West-Siberian agroforestry station, Povolzhsky agroforestry station, Nizhnevolzhsky station on selection of tree species, etc.). The region has established introduction resources, seed plantations of tree and shrub biodiversity (340 ha of forest-seed plantations, more than 150 ha of forest plantations). Complex resistant varieties were obtained, a valuable breeding gene pool was identified, and production nurseries were organized in the experimental network of the Federal Scientific Center of Agroecology of the Russian Academy of Sciences (Nizhnevolzhskaya station for selection of tree species) for rationalization of nature management, fight against drought and desertification in low-forest areas. A strategy for breeding stone crops has been developed to accelerate the creation of a new source material and varieties for cultivation using modern intensive technologies that ensure stable productivity with high fruit quality in the Lower Volga region. An extensive collection of field crops, theoretical base and practical developments has been accumulated. Including annually replenished collections of more than 2500 hybrids and varietals of winter and spring wheat, spring barley, seed millet, sorghum crops, trees, shrubs, perennial fruit crops, as well as a database of traits for more than 5000 samples of complex resistant to stress factors. The mission of the breeding and seed center is to accelerate the creation and introduction into mass production of adapted innovative varieties and hybrids of agricultural and forest crops that meet the most modern requirements of agroecological regulations for the production and processing of agricultural products. This will ensure the development of both the internal food security of the region and the Russian Federation as a whole, and increase the export potential. The key regions of the Russian Federation for the development of the Program are the following: Volgograd, Saratov, Orenburg, Samara, Oryol, Kursk, Astrakhan regions, Altai, Stavropol territory, Republic Kalmykia. Федеральный научный центр агроэкологии Российской академии наук имеет значительный опыт создания и внедрения результатов научной работы, направленной на достижение высоких и устойчивых показателей в лесном и агропромышленном комплексе. Для создания селекционно-семеноводческого центра имеются обширные дендрологические коллекции, маточники, ценные декоративные плантации деревьев и кустарников (Самарская, Волгоградская, Орловская, Астраханская области, Алтайский и Ставропольский край), питомники и тепличные комплексы (Нижневолжская станция по селекции древесных пород). В регионе созданы интродукционные ресурсы, семенные плантации, производственные питомники биоразнообразия деревьев и кустарников (340 га лесных посевных плантаций, архивы клонов, более 150 га лесных плантаций). Создана обширная коллекция полевых культур (2500 гибридов и сортов озимой и яровой пшеницы, ярового ячменя, семян проса, сорго, технических культур, деревьев, кустарников, многолетних плодовых культур), теоретическая база и практические разработки. Миссия селекционно-семенного центра - ускорить создание и внедрение в серийное производство адаптированных инновационных сортов и гибридов сельскохозяйственных и лесных культур, отвечающих самым современным требованиям агроэкологических нормативов для производства и переработки сельскохозяйственной продукции.

Intercropping systems could improve utilization of the most important resources (soil, water and nutrients), provide a better control of weeds, pests and diseases, and finally higher productivity, especially under rain-fed growing conditions. This study aimed to determine the effects of three maize (Zea mays L.) prolific hybrids (FAO 500, 600 and 700) and the spatial intercrop patterns on the above-ground biomass and grain yields of maize and soybean (Glycine max L. Merrill), on chernozem soil type at Zemun Polje, Belgrade, in 2003, 2004 and 2005. The experimental design was a complete randomized block with four replications and three treatments: 3 rows of maize and 3 rows of soybean in strips for each maize hybrid (three variants, 3 rows of maize and 3 rows of soybean in alternate rows for each hybrid (another three variants) and monocrops of both maize and soybeans. To optimize the ecological and economic benefits of maize/soybean intercrop in terms of yield, variety selection and compatibility of the component crops should be made using established agronomic management practices involving the two crops. Suitable maize varieties for maize/soybean intercrop systems are varieties that have less dense canopy. These varieties would therefore have lesser shading effect to the understory beans. However, establishment of an appropriate spatial arrangement of the component crops would be essential to alleviate negative effects especially on the less competitive crop. The intercropping system in alternate rows showed significantly higher above-ground biomass and grain yields in comparation with both the strip intercropping system and maize monocrops in 2004. Soybean gave significantly lower above-ground biomass and grain yield in intercrops than in monocrops. Maize prolific hybrid growing in intercropping with soybean as legume crop, increased productivity of cropping system, especially in favourable agroecological conditions. Maize and soybean yields reduction could have also been due to interspecific competition for resources such as nutrients and water. Moreover, performance of the currently grown varieties in the semi-arid regions depends on the amount of rainfall received during the growing season.

In the Volgograd region, which belongs to low-forest regions, old-growth plantings pre-dominate, in which about 80,0% of the total dendrological composition is accounted for by repre-sentatives of the generic Ulmus complex. In the conditions of urbanization, the pathological pro-cesses and the weakening of woody plants increases. The stable weakened state of the elm trees is typical for squares and roadside plantings (Bsr = 3.28-3.36, respectively). Favorable conditions for maintaining the life optimum of elms are formed in parks, protective forest strips and arbore-tums, where healthy or weakened trees predominate (Bsr = 1,82-1,69-1,87 respectively). Phyl-lophages of different ecological groups are trophically related to the arboreal species of Ulmus. Among leaf-eating pests, Xanthogaleruca luteola Mull is of important economic importance. The pest population varies depending on the ecological conditions of the biotopes and Ulmus species. Keywords: ULMUS, PROTECTIVE FOREST STANDS, CONDITION CATEGORY, MONITORING, ANTHROPOGENIC PRESSURE, PESTS, PEST POPULATION

The problem of optimization of ecological conditions of urbanized and agricultural areas of the arid zone is especially urgent nowadays. Severe forest conditions make it necessary to optimize the environment due to the protective plantations of different types and ecological categories. The use of woody plants unusual for a given area as part of multifunctional stands is one of the main methods for increasing the ecological capacity of the territory, changing the structure and population of insects. The study was conducted in Volgograd, Samara and Rostov regions. By the degree of biotic potential accumulation among the trees adapted in the arid region, plants of the Ulmaceae, Rosaceae and Fabaceae families are distinguished. The introduction of woody vegetation into new territories is also accompanied by the penetration of alien species of pests. Currently, among the phyllophages of woody plants used in landscaping various landscapes, there are invader insects. In urban areas, these species are particularly closely associated with Robinia pseudoacacia L. The most numerous as part of the pests of assimilation apparatus of this plant are Obolodiplosis robiniae (Haldeman, 1847) and Nematus tibialis (Neuman, 1837). Dissemination of Robinia by these insects in the protective forest plantations varies greatly. In the roadside forest plantations and the agroforest plantations in the composition of dendroflora the species of the family Ulmaceae are predominant. Among the invasive species that appeared in them is Aproceros leucopoda (Takeuchi, 1939); in these stands, it almost completely destroys the elm foliage. In the crowns of trees of recreational landscaping, single individuals of this species are found. Among the dendrophages of the stands of urbanized and forest-agrarian landscapes, open-living leaf-eating insects giving outbreaks of mass reproduction (Xanthogaleruca luteola, Dicranura ulmi, Cladius ulmi, Aproceros leucopoda) stand out. Wide spread and increase in the number is observed in Obolodiplosis robiniae and Fenusa ulmi.

In November of 1984 and 1985, Euphorbia lathyris was planted into a field naturally infested with Macrophomina phaseolina located at the Campbell Avenue Farm in Tucson, Arizona. Plants without foliar symptoms and rhizosphere soil were sampled regularly from emergence until the following May or June. Soil rhizosphere populations ranged from 0.7-3.0 cfu/g soil in 1985 to 8.0-24.1 cfu/g soil in 1986, and did not change significantly over either growing season (P > 0.05). Both the incidence of disease and the number of infection sites per cm of root increased significantly (P < 0.05) over each growing season and were not related to rhizosphere soil populations of M. phaseolina (P > 0.05). The distribution of infection sites along the tap root over both growing seasons remained the same in that most were located in the top 0-7 cm of tap root. Infected E. lathyris without apparent symptoms were subjected to low-water and high-temperature stress treatments in growth chambers. Root infection was not found to be dependent upon any stress. Lesion development was significantly dependent upon the imposition of any stress treatment, and further root colonization was significantly dependent upon low-water stress (P < 0.05). M. phaseolina was consistently recovered from asymptomatic roots. A consistently lower leaf water potential was measured on infected E. lathyris than from non-infected controls when no stress treatment was applied. Polyclonal antisera made against hyphae and microsclerotia of M. phaseolina was not successful in detecting this pathogen in E. lathyris by I-ELISA. Antisera applied to fresh thin sections of infected plant tissue was effective in staining hyphae of M. phaseolina when used with a second antibody conjugated to fluorescence isothiocyanate or to an enzyme (to which a substrate was added to "stain" hyphae).

Forage cactus is a perennial crop, which has been widely exploited for feeding ruminants in the semiarid region of different countries around the world. The main objective of this chapter is to describe the use and importance of spineless cactus as forage, desertification mitigation, source of water for animals and a source of income for producers in semiarid regions. The main species explored in Brazil are Opuntia spp. and Nopalea spp., due to characteristics such as resistance to pests, productivity, water-use efficiency and demand for soil fertility. The productivity of the species in a region will depend on its morphological characteristics, plant spacing, planting systems and its capacity to adapt to climatic and soil conditions. In other parts of the world, cactus species are the most cosmopolitan and destructive among invasive plants. However, the use of spineless forage cactus in areas where it can develop normally and may become the basis for ruminants’ feed would increase the support capacity production systems. Thus, specifically for Brazil’s semiarid region these species can make the difference as forage for animal feeding, cultivated as monoculture or intercropped, for soil conservation and desertification mitigation, source of water for animals, preservation of the Caatinga biome and be a potential source of income for producers if cultivated as vegetable for nutritional properties and medicinal derivative of fruits and cladodes for exports.

Thus, the primary task of breeding is to create varieties that combine high yield with drought resistance. It is important to have a sufficiently high level of adaptability of the variety to the conditions of the growing region, where the variety remains the main reserve for resource conservation and intensification of agricultural production in Ukraine. Generally accepted methods are used, namely scientific, special, laboratory, mathematical and statistical. In conditions of insufficient moisture, the use of early maturing and very early maturing varieties is relevant. Indicators of soybean yield in all oblasts of Ukraine are provided. According to the results of the analysis of 17-year meteorological observations, it was found that the climatic characteristics of Poltava oblast became more arid. The dynamics of indicators of the soybean gross yield in Poltava oblast (2002–2018) is analyzed against the background of the amount of precipitation during the growing season (4–8 months). In the research laboratory of Breeding, Seed Production and Varietal Soybean Agrotechnics of Poltava State Agrarian University, it was created Almaz, Antratsyt, Adamos, Aleksandryt, Akvamaryn, Avantiuryn soybean varieties, which were listed the State Register of Plant Varieties Suitable for Spreading in Ukraine. Indicators of agricultural suitability of these varieties and their advantages are presented. Varieties of Poltava breeding are distinguished by drought resistance, resistance to diseases and pests, non-lodging, when the seeds mature, the beans do not crack. These varieties are guaranteed predecessors for winter crops in the Steppe and Forest-Steppe of Ukraine.

People value biodiversity found in tropical rain forests for a variety of utilitarian, aesthetic, moral, ecological, and socioeconomic reasons (Botkin and Talbot, 1992). For instance, traditional medicines derived from plant and animal species found in the tropics provide health services to rural and urban populations; about 25 percent of the pharmaceutical products produced in the United States are associated with plants (WRI et al., 1992). Genetic materials extracted from plant and animal species have contributed to the development of commercial agricultural products (e.g., new varieties of wheat, maize, and rice) that are more resistant to pests and diseases. And nature tourism, often associated with protected wildlife habitats, has become an important source of income, generating about $ 12 billion annually in worldwide earnings (Lindberg, 1991). There are important socioeconomic and political considerations in the valuation of biological resources and the protection of biodiversity. First, the benefits that result from biodiversity have spatial and temporal dimensions. The ecological services linked with biodiversity, such as clean air and water, and the use of genetic material and ingredients extracted from plants, animals, and microorganisms, occur at different places and at different times, often beyond the “economic time scale” of individuals. Second, biodiversity has characteristics of a public good locally arid nationally and may be considered a “global environmental good” in an international context. The benefits of public goods flow to all people regardless of whether they have paid for the good, which means that public goods suffer from the problem of “free riders.” In a national context, economists have long focused attention on the difficulty of financing public goods and have generally concluded that such goods will be underprovided by markets. In the international context, the provision and financing of public goods is even more problematic. These characteristics make management of biodiversity institutionally complex and create problems in defining property rights. Third, conservation of biodiversity can create significant nonuse values. By its very existence, biodiversity can generate economic value without requiring actual use and can provide value by leaving open the option of future use.

Date palm (Phoenix dactylifera L.) is the major fruit tree grown in arid areas in the Middle East and North Africa. In the last century, dates were introduced to new regions including the USA. Date palms are traditionally propagated through offshoots. Expansion of modern date palm groves led to the development of Tissue Culture propagation methods that generate a large number of homogenous plants, have no seasonal effect on plant source and provide tools to fight the expansion of date pests and diseases. The disadvantage of this procedure is the occurrence of off-type trees which differ from the original cultivar. In the present project we focused on two of the most common date palm off-types: (1) trees with reduced fruit setting, in which most of the flowers turn into three-carpel parthenocarpic fruits. In a severe form, multi-carpel flowers and fruitlets (with up to six or eight carpels instead of the normal three-carpel flowers) are also formed. (2) dwarf trees, having fewer and shorter leaves, very short trunk and are not bearing fruits at their expected age, compared to the normal trees. Similar off-types occur in other crop species propagated by tissue culture, like banana (mainly dwarf plants) or oil palm (with a common 'Mantled' phenotype with reduced fruit setting and occurrence of supernumerary carpels). Some off-types can only be detected several years after planting in the fields. Therefore, efficient methods for prevention of the generation of off-types, as well as methods for their detection and early removal, are required for date palms, as well as for other tissue culture propagated crops. This research is aimed at the understanding of the mechanisms by which off-types are generated, and developing markers for their early identification. Several molecular and genomic approaches were applied. Using Methylation Sensitive AFLP and bisulfite sequencing, we detected changes in DNA methylation patterns occurring in off-types. We isolated and compared the sequence and expression of candidate genes, genes related to vegetative growth and dwarfism and genes related to flower development. While no sequence variation were detected, changes in gene expression, associated with the severity of the "fruit set" phenotype were detected in two genes - PdDEF (Ortholog of rice SPW1, and AP3 B type MADS box gene), and PdDIF (a defensin gene, highly homologous to the oil palm gene EGAD). We applied transcriptomic analyses, using high throughput sequencing, to identify genes differentially expressed in the "palm heart" (the apical meristem and the region of embryonic leaves) of dwarf vs. normal trees. Among the differentially expressed genes we identified genes related to hormonal biosynthesis, perception and regulation, genes related to cell expansion, and genes related to DNA methylation. Using Representation Difference Analyses, we detected changes in the genomes of off-type trees, mainly chloroplast-derived sequences that were incorporated in the nuclear genome and sequences of transposable elements. Sequences previously identified as differing between normal and off-type trees of oil palms or banana, successfully identified variation among date palm off-types, suggesting that these represent highly labile regions of monocot genomes. The data indicate that the date palm genome, similarly to genomes of other monocot crops as oil palm and banana, is quite unstable when cells pass through a cycle of tissue culture and regeneration. Changes in DNA sequences, translocation of DNA fragments and alteration of methylation patterns occur. Consequently, patterns of gene expression are changed, resulting in abnormal phenotypes. The data can be useful for future development of tools for early identification of off-type as well as for better understanding the phenomenon of somaclonal variation during propagation in vitro.

The trees, developed green spaces, and natural areas within the City of Austin’s 400,882 acres will face direct and indirect impacts from a changing climate over the 21st century. This assessment evaluates the vulnerability of urban trees and natural and developed landscapes within the City Austin to a range of future climates. We synthesized and summarized information on the contemporary landscape, provided information on past climate trends, and illustrated a range of projected future climates. We used this information to inform models of habitat suitability for trees native to the area. Projected shifts in plant hardiness and heat zones were used to understand how less common native species, nonnative species, and cultivars may tolerate future conditions. We also assessed the adaptability of planted and naturally occurring trees to stressors that may not be accounted for in habitat suitability models such as drought, flooding, wind damage, and air pollution. The summary of the contemporary landscape identifies major stressors currently threatening trees and forests in Austin. Major current threats to the region’s urban forest include invasive species, pests and disease, and development. Austin has been warming at a rate of about 0.4°F per decade since measurements began in 1938 and temperature is expected to increase by 5 to 10°F by the end of this century compared to the most recent 30-year average. Both increases in heavy rain events and severe droughts are projected for the future, and the overall balance of precipitation and temperature may shift Austin’s climate to be more similar to the arid Southwest. Species distribution modeling of native trees suggests that suitable habitat may decrease for 14 primarily northern species, and increase for four more southern species. An analysis of tree species vulnerability that combines model projections, shifts in hardiness and heat zones, and adaptive capacity showed that only 3% of the trees estimated to be present in Austin based on the most recent Urban FIA estimate were considered to have low vulnerability in developed areas. Using a panel of local experts, we also assessed the vulnerability of developed and natural areas. All areas were rated as having moderate to moderate-high vulnerability, but the underlying factors driving that vulnerability differed by natural community and between East and West Austin. These projected changes in climate and their associated impacts and vulnerabilities will have important implications for urban forest management, including the planting and maintenance of street and park trees, management of natural areas, and long-term planning.