scholarly journals Does susceptibility to heat stress confound screening for drought tolerance in rice?

2011 ◽  
Vol 38 (4) ◽  
pp. 261 ◽  
Author(s):  
Krishna S. V. Jagadish ◽  
Jill E. Cairns ◽  
Arvind Kumar ◽  
Impa M. Somayanda ◽  
Peter Q. Craufurd
Keyword(s):  
Heat Stress ◽  
Drought Tolerance ◽  
Candidate Genes ◽  
Tissue Temperature ◽  
Drought Tolerant ◽  
Hot Season ◽  
Dry Seasons ◽  
Drought And Heat Stress ◽  
Drought Screening ◽  
Mapping Populations

Drought affected rice areas are predicted to double by the end of this century, demanding greater tolerance in widely adapted mega-varieties. Progress on incorporating better drought tolerance has been slow due to lack of appropriate phenotyping protocols. Furthermore, existing protocols do not consider the effect of drought and heat interactions, especially during the critical flowering stage, which could lead to false conclusion about drought tolerance. Screening germplasm and mapping-populations to identify quantitative trait loci (QTL)/candidate genes for drought tolerance is usually conducted in hot dry seasons where water supply can be controlled. Hence, results from dry season drought screening in the field could be confounded by heat stress, either directly on heat sensitive processes such as pollination or indirectly by raising tissue temperature through reducing transpirational cooling under water deficit conditions. Drought-tolerant entries or drought-responsive candidate genes/QTL identified from germplasm highly susceptible to heat stress during anthesis/flowering have to be interpreted with caution. During drought screening, germplasm tolerant to water stress but highly susceptible to heat stress has to be excluded during dry and hot season screening. Responses to drought and heat stress in rice are compared and results from field and controlled environment experiments studying drought and heat tolerance and their interaction are discussed.

scholarly journals Lipid Peroxidation and Chlorophyll Fluorescence of Photosystem II Performance during Drought and Heat Stress is Associated with the Antioxidant Capacities of C3 Sunflower and C4 Maize Varieties

2020 ◽  
Vol 21 (14) ◽  
pp. 4846
Author(s):  
Dilek Killi ◽  
Antonio Raschi ◽  
Filippo Bussotti
Keyword(s):  
Lipid Peroxidation ◽  
Antioxidant Activity ◽  
Heat Stress ◽  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Membrane Damage ◽  
Drought Tolerant ◽  
Maize Varieties ◽  
Catalase Peroxidase ◽  
Drought And Heat Stress

Agricultural production is predicted to be adversely affected by an increase in drought and heatwaves. Drought and heat damage cellular membranes, such as the thylakoid membranes where photosystem II occurs (PSII). We investigated the chlorophyll fluorescence (ChlF) of PSII, photosynthetic pigments, membrane damage, and the activity of protective antioxidants in drought-tolerant and -sensitive varieties of C3 sunflower and C4 maize grown at 20/25 and 30/35 °C. Drought-tolerant varieties retained PSII electron transport at lower levels of water availability at both temperatures. Drought and heat stress, in combination and isolation, had a more pronounced effect on the ChlF of the C3 species. For phenotyping, the maximum fluorescence was the most effective ChlF measure in characterizing varietal variation in the response of both species to drought and heat. The drought-tolerant sunflower and maize showed lower lipid peroxidation under drought and heat stress. The greater retention of PSII function in the drought-tolerant sunflower and maize at higher temperatures was associated with an increase in the activities of antioxidants (glutathione reductase, superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase), whereas antioxidant activity declined in the drought-sensitive varieties. Antioxidant activity should play a key role in the development of drought- and heat-tolerant crops for future food security.

scholarly journals Transcripts of wheat at a target locus on chromosome 6B associated with increased yield, leaf mass and chlorophyll index under combined drought and heat stress

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241966
Author(s):  
Jessica Schmidt ◽  
Melissa Garcia ◽  
Chris Brien ◽  
Priyanka Kalambettu ◽  
Trevor Garnett ◽  
...  
Keyword(s):  
Heat Stress ◽  
Stress Tolerance ◽  
Candidate Genes ◽  
Abiotic Stress Tolerance ◽  
Enrichment Analysis ◽  
Genotyping By Sequencing ◽  
Differentially Expressed ◽  
Pathway Enrichment Analysis ◽  
Heat Stress Tolerance ◽  
Drought And Heat Stress

Drought and heat stress constrain wheat (Triticum aestivum L.) yields globally. To identify putative mechanisms and candidate genes associated with combined drought and heat stress tolerance, we developed bread wheat near-isogenic lines (NILs) targeting a quantitative trait locus (QTL) on chromosome 6B which was previously associated with combined drought and heat stress tolerance in a diverse panel of wheats. Genotyping-by-sequencing was used to identify additional regions that segregated in allelic pairs between the recurrent and the introduced exotic parent, genome-wide. NILs were phenotyped in a gravimetric platform with precision irrigation and exposed to either drought or to combined drought and heat stress from three days after anthesis. An increase in grain weight in NILs carrying the exotic allele at 6B locus was associated with thicker, greener leaves, higher photosynthetic capacity and increased water use index after re-watering. RNA sequencing of developing grains at early and later stages of treatment revealed 75 genes that were differentially expressed between NILs across both treatments and timepoints. Differentially expressed genes coincided with the targeted QTL on chromosome 6B and regions of genetic segregation on chromosomes 1B and 7A. Pathway enrichment analysis showed the involvement of these genes in cell and gene regulation, metabolism of amino acids and transport of carbohydrates. The majority of these genes have not been characterized previously under drought or heat stress and they might serve as candidate genes for improved abiotic stress tolerance.

Inheritance and mapping of drought tolerance in soybean at seedling stage using bulked segregant analysis

2020 ◽  
Vol 18 (2) ◽  
pp. 63-70
Author(s):  
V. Sreenivasa ◽  
S. K. Lal ◽  
P. Kiran Babu ◽  
H. K. Mahadeva Swamy ◽  
Raju R. Yadav ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Bulked Segregant Analysis ◽  
Seedling Survival ◽  
Yield Reduction ◽  
Single Marker Analysis ◽  
Drought Tolerant ◽  
Single Marker ◽  
Improvement Programs ◽  
Mapping Populations ◽  
Map Distance

AbstractOccurrence of drought under rainfed conditions is the foremost factor responsible for yield reduction in soybean. Developing soybean cultivars with an inherent ability to withstand drought would immensely benefit the soybean production in rainfed areas. In the present study, F2 derived mapping populations were developed by crossing drought tolerant (PK 1180, SL 46) and susceptible (UPSL 298, PK 1169) genotypes to investigate the inheritance of seedling survival drought mechanisms and to identify simple-sequence repeat (SSR) markers associated with them, using bulked segregant analysis. Parents as well as a F2 derived mapping population were screened for drought tolerance based on seedling survivability under controlled conditions. Segregation analysis of F2 population derived from a cross between PK 1180 × UPSL 298 was previously shown to have a 3:1 tolerant to susceptible ratio and a probability of 0.61 at a χ2(3:1) value of 0.258. This was confirmed in another F2 population derived from a cross between PK 1169 × SL 46 with a χ2(3:1) value of 0.145 obtained at a probability of 0.70. One SSR marker Satt277 showed polymorphism between contracting bulks (tolerant and susceptible) out of 50 polymorphic markers identified during parental polymorphism. Single marker analysis suggested that the marker, Satt277 is linked to seedling survival drought tolerance and is located on chromosome linkage group C2 (chr 6) with a map distance of 3.40 cM. The tolerant genotypes identified could be used as a donor in soybean improvement programs. The marker identified can be used in marker-assisted selection while screening large collection of germplasm.

scholarly journals Effects of individual and combined heat and drought stress during seed filling on the oxidative metabolism and yield of chickpea (Cicer arietinum) genotypes differing in heat and drought tolerance

2017 ◽  
Vol 68 (9) ◽  
pp. 823 ◽  
Author(s):  
Rashmi Awasthi ◽  
Pooran Gaur ◽  
Neil C. Turner ◽  
Vincent Vadez ◽  
Kadambot H. M. Siddique ◽  
...  
Keyword(s):  
Heat Stress ◽  
Drought Stress ◽  
Seed Yield ◽  
Oxidative Metabolism ◽  
Combined Stress ◽  
Seed Filling ◽  
Stress Treatment ◽  
Drought Tolerant ◽  
The Individual ◽  
Drought And Heat Stress

Drought and heat stress are two major constraints that limit chickpea (Cicer arietinum L.) yield, particularly during seed filling. The present study aimed (i) to assess the individual and combined effects of drought and heat stress on oxidative metabolism during seed filling, and (ii) to determine any genetic variation in oxidative metabolism among genotypes differing in drought and heat tolerance and sensitivity. The plants were raised in outdoor conditions with two different times of sowing, one in November (normal-sown, temperatures <32°C−20°C (day–night) during seed filling), and the other in February (late-sown, temperatures >32°C−20°C (day–night) during seed filling). Plants were regularly irrigated to prevent any water shortage until the water treatments were applied. At both sowing times, the drought treatment was applied during seed filling (at ~75% podding) by withholding water from half of the pots until the relative leaf water content (RLWC) of leaves on the top three branches reached 42–45%, whereas leaves in the fully irrigated control plants were maintained at RLWC 85–90%. Drought-stressed plants were then rewatered and maintained under fully irrigated conditions until maturity. Several biochemical parameters were measured on the leaves and seeds at the end of the stress treatments, and seed yield and aboveground biomass were measured at maturity. Individual and combined stresses damaged membranes, and decreased PSII function and leaf chlorophyll content, more so under the combined stress treatment. The levels of oxidative molecules (malondialdehyde (MDA) and H2O2) markedly increased compared with the control plants in all stress treatments, especially across genotypes in the combined heat + drought stress treatment (increases in leaves: MDA 5.4–8.4-fold and H2O2 5.1–7.1-fold; in seeds: MDA 1.9–3.3-fold and H2O2 3.8–7.9-fold). The enzymatic and non-enzymatic antioxidants related to oxidative metabolism increased under individual stress treatments but decreased in the combined heat + drought stress treatment. Leaves had higher oxidative damage than seeds, and this likely inhibited their photosynthetic efficiency. Yields were reduced more by drought stress than by heat stress, with the lowest yields in the combined heat + drought stress treatment. Heat- and drought-tolerant genotypes suffered less damage and had higher yields than the heat- and drought-sensitive genotypes under the individual and combined stress treatments, suggesting partial cross-tolerance in these genotypes. A drought-tolerant genotype ICC8950 produced more seed yield under the combined heat + drought stress than other genotypes, and this was associated with low oxidative damage in leaves and seeds.

scholarly journals Classification of Crop Tolerance to Heat and Drought—A Deep Convolutional Neural Networks Approach

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 833 ◽  
Author(s):  
Saeed Khaki ◽  
Zahra Khalilzadeh ◽  
Lizhi Wang
Keyword(s):  
Heat Stress ◽  
Yield Loss ◽  
Large Datasets ◽  
Deep Convolutional Neural Networks ◽  
Corn Hybrids ◽  
Crop Tolerance ◽  
Drought Tolerant ◽  
Unsupervised Approach ◽  
Drought And Heat Stress

Environmental stresses, such as drought and heat, can cause substantial yield loss in agriculture. As such, hybrid crops that are tolerant to drought and heat stress would produce more consistent yields compared to the hybrids that are not tolerant to these stresses. In the 2019 Syngenta Crop Challenge, Syngenta released several large datasets that recorded the yield performances of 2452 corn hybrids planted in 1560 locations between 2008 and 2017 and asked participants to classify the corn hybrids as either tolerant or susceptible to drought stress, heat stress and combined drought and heat stress. However, no data was provided that classified any set of hybrids as tolerant or susceptible to any type of stress. In this paper, we present an unsupervised approach to solving this problem, which was recognized as one of the winners in the 2019 Syngenta Crop Challenge. Our results labeled 121 hybrids as drought tolerant, 193 as heat tolerant and 29 as tolerant to both stresses.

scholarly journals Comprehensive Meta-Analysis of Maize QTLs Associated With Grain Yield, Flowering Date and Plant Height Under Drought Conditions

2019 ◽  
Vol 11 (8) ◽  
pp. 1 ◽  
Author(s):  
Songtao Liu ◽  
Tinashe Zenda ◽  
Xuan Wang ◽  
Guo Liu ◽  
Hongyu Jin ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Candidate Genes ◽  
Gene Networks ◽  
Quantitative Traits ◽  
Zea Mays L ◽  
Meta Analysis ◽  
Related Gene ◽  
Rice Gene ◽  
Precise Location ◽  
Mapping Populations

Drought remains the primary abiotic constraint to maize (Zea mays L.) productivity globally. Maize drought response involves several regulatory quantitative traits and complex gene networks. Therefore, precise location of drought-related quantitative trait loci (QTL) is imperative for drought tolerance breeding. Despite numerous studies identifying several drought-related maize QTLs, some QTL from particular genetic backgrounds showed smaller effects or could not be identified at all in different backgrounds, affected by marker sets, experimental design, mapping populations and statistical methods. Herein, therefore; using 457 published maize QTLs conferring for 18 traits, we have performed meta-analysis of data from various experiments to obtain meta-QTL (MQTL), integrate these fruitful QTL and to mine candidate genes related to drought. Resultantly, 24 MQTL with confidence interval (CI) &lt; 5 cm were identified to be hot regions. Additionally, 47 drought related gene loci were observed and several candidate genes of the hot MQTL were reorganized by bioinformatics techniques. Thirteen gene (sod4, taf1, rps1, nthr3, oc13, bas, apx1, asn4, pck2, nac1, gst2, ao1 and kch4) loci of hot MQTL regions were homologous to their corresponding gene sequences from the PlantGDB database (http://www.plantgdb.org/search/). Further, we used a comparative genomics approach to identify the homologous regions of MQTL in rice (Oryza sativa Japonica) database (http://www.gramene.org) and observed that drought-related rice gene ATG6 was homologous to maize candidate genes GRMZM2G027857_T01 and GRMZM2G027857_T02. Conclusively, our identified MQTLs with narrowed CI could be useful for marker-assisted selection and the candidate genes harnessed for maize drought tolerance breeding.

scholarly journals Identification of Main-Effect and Environmental Interaction QTL and Their Candidate Genes for Drought Tolerance in a Wheat RIL Population Between Two Elite Spring Cultivars

2021 ◽  
Vol 12 ◽  
Author(s):  
S. M. Hisam Al Rabbi ◽  
Ajay Kumar ◽  
Sepehr Mohajeri Naraghi ◽  
Suraj Sapkota ◽  
Mohammed S. Alamri ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Candidate Genes ◽  
Phenotypic Variation ◽  
Kernel Weight ◽  
Snp Markers ◽  
Expression Variability ◽  
Volume Weight ◽  
Drought Tolerant ◽  
Ril Population ◽  
Major Qtl

Understanding the genetics of drought tolerance can expedite the development of drought-tolerant cultivars in wheat. In this study, we dissected the genetics of drought tolerance in spring wheat using a recombinant inbred line (RIL) population derived from a cross between a drought-tolerant cultivar, ‘Reeder’ (PI613586), and a high-yielding but drought-susceptible cultivar, ‘Albany.’ The RIL population was evaluated for grain yield (YLD), grain volume weight (GVW), thousand kernel weight (TKW), plant height (PH), and days to heading (DH) at nine different environments. The Infinium 90 k-based high-density genetic map was generated using 10,657 polymorphic SNP markers representing 2,057 unique loci. Quantitative trait loci (QTL) analysis detected a total of 11 consistent QTL for drought tolerance-related traits. Of these, six QTL were exclusively identified in drought-prone environments, and five were constitutive QTL (identified under both drought and normal conditions). One major QTL on chromosome 7B was identified exclusively under drought environments and explained 13.6% of the phenotypic variation (PV) for YLD. Two other major QTL were detected, one each on chromosomes 7B and 2B under drought-prone environments, and explained 14.86 and 13.94% of phenotypic variation for GVW and YLD, respectively. One novel QTL for drought tolerance was identified on chromosome 2D. In silico expression analysis of candidate genes underlaying the exclusive QTLs associated with drought stress identified the enrichment of ribosomal and chloroplast photosynthesis-associated proteins showing the most expression variability, thus possibly contributing to stress response by modulating the glycosyltransferase (TraesCS6A01G116400) and hexosyltransferase (TraesCS7B01G013300) unique genes present in QTL 21 and 24, respectively. While both parents contributed favorable alleles to these QTL, unexpectedly, the high-yielding and less drought-tolerant parent contributed desirable alleles for drought tolerance at four out of six loci. Regardless of the origin, all QTL with significant drought tolerance could assist significantly in the development of drought-tolerant wheat cultivars, using genomics-assisted breeding approaches.

scholarly journals Phenotyping Peanut Genotypes for Drought Tolerance

2016 ◽  
Vol 43 (1) ◽  
pp. 36-48 ◽  
Author(s):  
J.M. Luis ◽  
P. Ozias-Akins ◽  
C.C. Holbrook ◽  
R.C. Kemerait ◽  
J.L. Snider ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Canopy Temperature ◽  
Cost Effective ◽  
Aflatoxin Contamination ◽  
Drought Tolerant ◽  
Canopy Temperature Depression ◽  
Combined Use ◽  
Drought And Heat Stress

ABSTRACT Drought and heat stress can result in aflatoxin contamination of peanuts especially when this occurs during the last three to six wk of the growing season. Identifying drought-tolerant genotypes may aid in development of peanuts that are less susceptible to aflatoxin contamination. Research was conducted to phenotype seven peanut genotypes based on their response to drought stress. Six peanut genotypes that have exhibited lower aflatoxin and/or drought tolerance in previous researches (Tifguard, Tifrunner, Florida-07, PI 158839, NC 3033, C76-16) were compared to an aflatoxin-susceptible genotype, A72. The phenotyping methods included visual ratings, chlorophyll fluorescence (PIABS, ϕEO, and Fv/Fm), SPAD chlorophyll meter reading (SCMR), normalized difference vegetation index (NDVI), canopy temperature (CT), canopy temperature depression (CTD), and pod yield. Based on these traits, Tifguard and Tifrunner exhibited greater drought tolerance mechanisms than the other genotypes and may be good candidates to be incorporated in future drought tolerance studies. After the aflatoxin content of the different genotypes was measured, aflatoxin contamination showed high correlations with visual ratings (0.85), CTD (0.81), NDVI (0.79), and CT (0.73), and moderate correlations with Fv/Fm (0.62) and SCMR (0.57) (P ≥ 0.05). These easily measurable, rapid and cost-effective phenotyping methods may be used as alternative to more tedious and costly methods of identifying genotypes that are less susceptible to aflatoxin contamination. Using a combination of these methods is beneficial but not always practical. The combined use of visual ratings, CTD and NDVI is advised for initial evaluation of drought tolerance in peanut genotypes.

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.

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