scholarly journals Unraveling the Genetic Architecture of Two Complex, Stomata-Related Drought-Responsive Traits by High-Throughput Physiological Phenotyping and GWAS in Cowpea (Vigna. Unguiculata L. Walp)

2021 ◽  
Vol 12 ◽  
Author(s):  
Xinyi Wu ◽  
Ting Sun ◽  
Wenzhao Xu ◽  
Yudong Sun ◽  
Baogen Wang ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Genetic Mapping ◽  
Soil Water ◽  
Water Relations ◽  
High Throughput ◽  
Genetic Architecture ◽  
Stomatal Closure ◽  
Significant Snps ◽  
Soil Drought ◽  
Stomatal Control

Drought is one of the most devasting and frequent abiotic stresses in agriculture. While many morphological, biochemical and physiological indicators are being used to quantify plant drought responses, stomatal control, and hence the transpiration and photosynthesis regulation through it, is of particular importance in marking the plant capacity of balancing stress response and yield. Due to the difficulties in simultaneous, large-scale measurement of stomatal traits such as sensitivity and speed of stomatal closure under progressive soil drought, forward genetic mapping of these important behaviors has long been unavailable. The recent emerging phenomic technologies offer solutions to identify the water relations of whole plant and assay the stomatal regulation in a dynamic process at the population level. Here, we report high-throughput physiological phenotyping of water relations of 106 cowpea accessions under progressive drought stress, which, in combination of genome-wide association study (GWAS), enables genetic mapping of the complex, stomata-related drought responsive traits “critical soil water content” (θcri) and “slope of transpiration rate declining” (KTr). The 106 accessions showed large variations in θcri and KTr, indicating that they had broad spectrum of stomatal control in response to soil water deficit, which may confer them different levels of drought tolerance. Univariate GWAS identified six and fourteen significant SNPs associated with θcri and KTr, respectively. The detected SNPs distributed in nine chromosomes and accounted for 8.7–21% of the phenotypic variation, suggesting that both stomatal sensitivity to soil drought and the speed of stomatal closure to completion were controlled by multiple genes with moderate effects. Multivariate GWAS detected ten more significant SNPs in addition to confirming eight of the twenty SNPs as detected by univariate GWAS. Integrated, a final set of 30 significant SNPs associated with stomatal closure were reported. Taken together, our work, by combining phenomics and genetics, enables forward genetic mapping of the genetic architecture of stomatal traits related to drought tolerance, which not only provides a basis for molecular breeding of drought resistant cultivars of cowpea, but offers a new methodology to explore the genetic determinants of water budgeting in crops under stressful conditions in the phenomics era.

Leaf Gas Exchange and Water Relations of Lupins and Wheat. II. Root and Shoot Water Relations of Lupin During Drought-Induced Stomatal Closure

1989 ◽  
Vol 16 (5) ◽  
pp. 415 ◽  
Author(s):  
CR Jensen ◽  
IE Henson ◽  
NC Turner
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Transport ◽  
Water Uptake ◽  
Water Relations ◽  
Leaf Gas Exchange ◽  
Stomatal Closure ◽  
Soil Water Potential ◽  
Root Water Uptake ◽  
Leaf Conductance

Plants of Lupinus cosentinii Guss. cv. Eregulla were grown in a sandy soil in large containers in a glasshouse and exposed to drought by withholding water. Under these conditions stomatal closure had previously been shown to be initiated before a significant reduction in leaf water potential was detected. In the experiments reported here, no significant changes were found in water potential or turgor pressure of roots or leaves when a small reduction in soil water potential was induced which led to a 60% reduction in leaf conductance. The decrease in leaf conductance and root water uptake closely paralleled the fraction of roots in wet soil. By applying observed data of soil water and root characteristics, and root water uptake for whole pots in a single-root model, the average water potential at the root surface was calculated. Potential differences for water transport in the soil-plant system, and the resistances to water flow were estimated using the 'Ohm's Law' analogy for water transport. Soil resistance was negligible or minor, whereas the root resistance accounted for 61-72% and the shoot resistance accounted for about 30% of the total resistance. The validity of the measurements and calculations is discussed and the possible role of root- to-shoot communication raised.

scholarly journals Using high-throughput multiple optical phenotyping to decipher the genetic architecture of maize drought tolerance

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xi Wu ◽  
Hui Feng ◽  
Di Wu ◽  
Shijuan Yan ◽  
Pei Zhang ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Candidate Genes ◽  
High Throughput ◽  
Complex Traits ◽  
Genetic Architecture ◽  
World Population ◽  
Eqtl Analysis ◽  
New Genes ◽  
Computed Tomography Images ◽  
Drought Tolerant

Abstract Background Drought threatens the food supply of the world population. Dissecting the dynamic responses of plants to drought will be beneficial for breeding drought-tolerant crops, as the genetic controls of these responses remain largely unknown. Results Here we develop a high-throughput multiple optical phenotyping system to noninvasively phenotype 368 maize genotypes with or without drought stress over a course of 98 days, and collected multiple optical images, including color camera scanning, hyperspectral imaging, and X-ray computed tomography images. We develop high-throughput analysis pipelines to extract image-based traits (i-traits). Of these i-traits, 10,080 were effective and heritable indicators of maize external and internal drought responses. An i-trait-based genome-wide association study reveals 4322 significant locus-trait associations, representing 1529 quantitative trait loci (QTLs) and 2318 candidate genes, many that co-localize with previously reported maize drought responsive QTLs. Expression QTL (eQTL) analysis uncovers many local and distant regulatory variants that control the expression of the candidate genes. We use genetic mutation analysis to validate two new genes, ZmcPGM2 and ZmFAB1A, which regulate i-traits and drought tolerance. Moreover, the value of the candidate genes as drought-tolerant genetic markers is revealed by genome selection analysis, and 15 i-traits are identified as potential markers for maize drought tolerance breeding. Conclusion Our study demonstrates that combining high-throughput multiple optical phenotyping and GWAS is a novel and effective approach to dissect the genetic architecture of complex traits and clone drought-tolerance associated genes.

scholarly journals Photosynthetic response of European beech to atmospheric and soil drought

2014 ◽  
Vol 60 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Tibor Priwitzer ◽  
Daniel Kurjak ◽  
Jaroslav Kmeť ◽  
Zuzana Sitková ◽  
Adriana Leštianska
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Stomatal Closure ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
European Beech ◽  
Soil Drought ◽  
Control Group ◽  
Natural Soil ◽  
Chlorophyll Fluorescence Parameters

Abstract Physiological response of European beech under soil and atmospheric drought conditions was investigated in this study. A group of six beech trees was irrigated during the growing season 2012, while the second group of non-irrigated (control) beech trees was treated under natural soil drought. During the experiment, we observed more than 45-day long period when no precipitation fell on the soil surface. The relationship of PN (CO2 assimilation rate) to gS (stomatal conductance) was very tight in both groups, which indicates that stomatal opening was the main factor limiting PN. The statistically significant differences in gS between the groups of trees were revealed only on the last measuring day. The significant differences in PN were confirmed on the days when the differences in soil water potential (ΨS) appeared. On these measurement days, the PN values of irrigated individuals were approximately 1.9 or 3.3 times greater than the values of non-irrigated individuals. At the level of primary photosynthetic processes (chlorophyll fluorescence parameters) we did not observe lower values of the control individuals in comparison with the irrigated trees in any of the evaluated parameters. Long-term soil water deficit caused strong decrease of leaf water potential (ΨL) in the control trees, but ΨL values of the irrigated trees were also rather low due to diurnal dynamics in higher parts of crown. Close relationship between ΨL and gS was confirmed for the control (non-irrigated) trees, but could not be confirmed for the irrigated trees. We revealed significant influence of VPD (vapour pressure deficit of the air) on gS only in the control group. On the days when ΨS decreased, the stomata of the non-irrigated trees were closed in spite of the low VPD values. Almost complete stomatal closure in both groups of trees was caused by the increase of VPD to 1.2 kPa.

scholarly journals High-throughput phenotyping reveals differential transpiration behavior within the banana wild relatives highlighting diversity in drought tolerance

2021 ◽  
Author(s):  
David Eyland ◽  
Nathalie Luchaire ◽  
Llorenç Cabrera-Bosquet ◽  
Boris Parent ◽  
Steven Janssens ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
High Throughput ◽  
Environmental Conditions ◽  
Stomatal Closure ◽  
Soil Water Potential ◽  
Wild Relatives ◽  
Genotypic Differences ◽  
Breeding Programs ◽  
Drought Avoidance ◽  
High Throughput Phenotyping

Crop wild relatives, the closely related species of crops, may harbor potentially important sources of new allelic diversity for (a)biotic tolerance or resistance. However, to date wild diversity is only poorly characterized and evaluated. Banana has a large wild diversity but only a narrow proportion is currently used in breeding programs. The main objective of this work was to evaluate genotype-dependent transpiration responses in relation to the environment. By applying continuous high-throughput phenotyping, we were able to construct genotype-specific transpiration response models in relation to light, VPD and soil water potential. We characterized and evaluated 6 (sub)species and discerned four phenotypic clusters. Significant differences were observed in leaf area, cumulative transpiration and transpiration efficiency. We confirmed a general stomatal-driven ‘isohydric’ drought avoidance behavior, but discovered genotypic differences in the onset and intensity of stomatal closure. We pinpointed crucial genotype specific environmental conditions when drought avoidance mechanisms were initiated and when stress kicked in. Differences between (sub)species were more pronounced under certain environmental conditions, illustrating the need for high-throughput dynamic phenotyping, modelling and validation. We conclude that the banana wild relatives contain useful drought tolerance traits, emphasizing the importance of their conservation and potential for use in breeding programs.

scholarly journals Applying RGB- and Thermal-Based Vegetation Indices from UAVs for High-Throughput Field Phenotyping of Drought Tolerance in Forage Grasses

2021 ◽  
Vol 13 (1) ◽  
pp. 147
Author(s):  
Tom De Swaef ◽  
Wouter H. Maes ◽  
Jonas Aper ◽  
Joost Baert ◽  
Mathias Cougnon ◽  
...  
Keyword(s):  
Drought Stress ◽  
Drought Tolerance ◽  
Lolium Perenne ◽  
High Throughput ◽  
Festuca Arundinacea ◽  
Stress Index ◽  
Forage Grasses ◽  
Crop Water Stress Index ◽  
Ploidy Levels ◽  
Field Phenotyping

The persistence and productivity of forage grasses, important sources for feed production, are threatened by climate change-induced drought. Breeding programs are in search of new drought tolerant forage grass varieties, but those programs still rely on time-consuming and less consistent visual scoring by breeders. In this study, we evaluate whether Unmanned Aerial Vehicle (UAV) based remote sensing can complement or replace this visual breeder score. A field experiment was set up to test the drought tolerance of genotypes from three common forage types of two different species: Festuca arundinacea, diploid Lolium perenne and tetraploid Lolium perenne. Drought stress was imposed by using mobile rainout shelters. UAV flights with RGB and thermal sensors were conducted at five time points during the experiment. Visual-based indices from different colour spaces were selected that were closely correlated to the breeder score. Furthermore, several indices, in particular H and NDLab, from the HSV (Hue Saturation Value) and CIELab (Commission Internationale de l’éclairage) colour space, respectively, displayed a broad-sense heritability that was as high or higher than the visual breeder score, making these indices highly suited for high-throughput field phenotyping applications that can complement or even replace the breeder score. The thermal-based Crop Water Stress Index CWSI provided complementary information to visual-based indices, enabling the analysis of differences in ecophysiological mechanisms for coping with reduced water availability between species and ploidy levels. All species/types displayed variation in drought stress tolerance, which confirms that there is sufficient variation for selection within these groups of grasses. Our results confirmed the better drought tolerance potential of Festuca arundinacea, but also showed which Lolium perenne genotypes are more tolerant.

Transpiration Response to Vapor Pressure Deficit in Field Grown Peanut

2012 ◽  
Vol 39 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Maria Balota ◽  
Steve McGrath ◽  
Thomas G. Isleib ◽  
Shyam Tallury
Keyword(s):  
Vapor Pressure ◽  
Soil Water ◽  
Water Deficit ◽  
Water Conservation ◽  
Vapor Pressure Deficit ◽  
Stomatal Closure ◽  
Genotypic Variation ◽  
Moisture Stress ◽  
Breeding Lines ◽  
Wide Range

Abstract Water deficit, i.e., rainfall amounts and distribution, is the most common abiotic stress that limits peanut production worldwide. Even though extensive research efforts have been made to improve drought tolerance in peanut, performance of genotypes largely depends upon the environment in which they grow. Based on greenhouse experiments, it has been hypothesized that stomata closure under high vapor pressure deficit (VPD) is a mechanism of soil water conservation and it has been shown that genotypic variation for the response of transpiration rate to VPD in peanut exists. The objective of this study was to determine the relationship between stomatal conductance (gs) and VPD for field grown peanut in Virginia-Carolina (VC) rainfed environments. In 2009, thirty virginia-type peanut cultivars and advanced breeding lines were evaluated for gs at several times before and after rain events, including a moisture stress episode. In 2010, eighteen genotypes were evaluated for gs under soil water deficit. In 2009, VPD ranged from 1.3 to 4.2 kPa and in 2010 from 1.78 to 3.57 kPa. Under water deficit, genotype and year showed a significant effect on gs (P  =  0.0001), but the genotype × year interaction did not. During the water deficit episodes while recorded gs values were relatively high, gs was negatively related to VPD (R2  =  0.57, n  =  180 in 2009; R2  =  0.47, n  =  108 in 2010), suggesting that stomata closure is indeed a water conservation mechanism for field grown peanut. However, a wide range of slopes among genotype were observed in both years. Genotypes with significant negative relationships of gs and VPD under water deficit in both years were Florida Fancy, Gregory, N04074FCT, NC-V11, and VA-98R. While Florida Fancy, Gregory, and NC-V11 are known to be high yielding cultivars, VA-98R and line N04074FCT are not. The benefit of stomatal closure during drought episodes in the VC environments is further discussed in this paper.

High-throughput genetic mapping in Arabidopsis thaliana

1999 ◽  
Vol 261 (2) ◽  
pp. 408-415 ◽  
Author(s):  
M. R. Ponce ◽  
P. Robles ◽  
J. L. Micol
Keyword(s):  
Arabidopsis Thaliana ◽  
Genetic Mapping ◽  
High Throughput

Physiological and morphological responses to water stress in Aegilops biuncialis and Triticum aestivum genotypes with differing tolerance to drought

2004 ◽  
Vol 31 (12) ◽  
pp. 1149 ◽  
Author(s):  
István Molnár ◽  
László Gáspár ◽  
Éva Sárvári ◽  
Sándor Dulai ◽  
Borbála Hoffmann ◽  
...  
Keyword(s):  
Growth Rate ◽  
Triticum Aestivum ◽  
Water Stress ◽  
Drought Tolerance ◽  
Osmotic Stress ◽  
Biomass Production ◽  
Water Loss ◽  
Stomatal Closure ◽  
Co2 Assimilation ◽  
Wheat Genotypes

The physiological and morphological responses to water stress induced by polyethylene glycol (PEG) or by withholding water were investigated in Aegilops biuncialis Vis. genotypes differing in the annual rainfall of their habitat (1050, 550 and 225 mm year–1) and in Triticum aestivum L. wheat genotypes differing in drought tolerance. A decrease in the osmotic pressure of the nutrient solution from –0.027 to –1.8 MPa resulted in significant water loss, a low degree of stomatal closure and a decrease in the intercellular CO2 concentration (Ci) in Aegilops genotypes originating from dry habitats, while in wheat genotypes high osmotic stress increased stomatal closure, resulting in a low level of water loss and high Ci. Nevertheless, under saturating light at normal atmospheric CO2 levels, the rate of CO2 assimilation was higher for the Aegilops accessions, under high osmotic stress, than for the wheat genotypes. Moreover, in the wheat genotypes CO2 assimilation exhibited less or no O2 sensitivity. These physiological responses were manifested in changes in the growth rate and biomass production, since Aegilops (Ae550, Ae225) genotypes retained a higher growth rate (especially in the roots), biomass production and yield formation after drought stress than wheat. These results indicate that Aegilops genotypes, originating from a dry habitat have better drought tolerance than wheat, making them good candidates for improving the drought tolerance of wheat through intergeneric crossing.

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