Wheat Yield Loss Research Articles

Transcriptomic and co-expression network analyses on diverse wheat landraces identifies candidate master regulators of the response to early drought.

Over four billion people around the world rely on bread wheat (Triticum aestivum L.) as a major constituent of their diet. The changing climate, however, threatens the food security of these people, with periods of intense drought stress already causing widespread wheat yield losses. Much of the research into the wheat drought response has centred on the response to drought events later in development, during anthesis or grain filling. But as the timing of periods of drought stress become increasingly unpredictable, a more complete understanding of the response to drought during early development is also needed. Here, we utilized the YoGI landrace panel to identify 10,199 genes which were differentially expressed under early drought stress, before weighted gene co-expression network analysis (WGCNA) was used to construct a co-expression network and identify hub genes in modules particularly associated with the early drought response. Of these hub genes, two stood out as novel candidate master regulators of the early drought response - one as an activator (TaDHN4-D1; TraesCS5D02G379200) and the other as a repressor (uncharacterised gene; TraesCS3D02G361500). As well as appearing to coordinate the transcriptional early drought response, we propose that these hub genes may be able to regulate the physiological early drought response due to potential control over the expression of members of gene families well-known for their involvement in the drought response in many plant species, namely dehydrins and aquaporins, as well as other genes seemingly involved in key processes such as, stomatal opening, stomatal closing, stomatal morphogenesis and stress hormone signalling.

Sensitivity of Puccinia triticina f. sp. tritici from China to Triadimefon and Resistance Risk Assessment.

Wheat leaf rust, caused by Puccinia triticina f. sp. tritici (Pt), is distributed widely in wheat-producing areas and results in serious yield losses worldwide. In China, leaf rust has been largely controlled with a demethylation inhibitor (DMI) fungicide, triadimefon. Although high levels of fungicide resistance in pathogens have been reported, no field failure of wheat leaf rust to DMI fungicides has been reported in China. A resistance risk assessment of triadimefon to Pt was investigated in the present study. The sensitivity of 197 Pt isolates across the country to triadimefon was determined, and the density distribution of EC50 values (concentration at which mycelial growth is inhibited by 50%) showed a continuous multimodal curve because of the extensive use of this fungicide in wheat production, with a mean value of 0.46 μg/ml. The majority of the tested Pt isolates were sensitive to triadimefon, whereas 10.2% developed varying degrees of resistance. Characterization of parasitic fitness revealed that the triadimefon-resistant isolates exhibited strong adaptive traits in urediniospore germination rate, latent period, sporulation intensity, and lesion expansion rate. No correlation was observed between triadimefon and tebuconazole and hexaconazole, which have the similar mode of action, or pyraclostrobin and flubeneteram, which have different modes of action. Overexpression of the target gene Cyp51 led to the triadimefon resistance of Pt. The risk of resistance to triadimefon in Pt may be low to moderate. This study provided important data for fungicide resistance risk management against wheat leaf rust.

Defence-related metabolic changes in wheat (Triticum aestivum L.) seedlings in response to infection by Puccinia graminis f. sp. tritici.

Stem rust caused by the pathogen Puccinia graminis f. sp. tritici is a destructive fungal disease-causing major grain yield losses in wheat. Therefore, understanding the plant defence regulation and function in response to the pathogen attack is required. As such, an untargeted LC-MS-based metabolomics approach was employed as a tool to dissect and understand the biochemical responses of Koonap (resistant) and Morocco (susceptible) wheat varieties infected with two different races of P. graminis (2SA88 [TTKSF] and 2SA107 [PTKST]). Data was generated from the infected and non-infected control plants harvested at 14- and 21- days post-inoculation (dpi), with 3 biological replicates per sample under a controlled environment. Chemo-metric tools such as principal component analysis (PCA), orthogonal projection to latent structures-discriminant analysis (OPLS-DA) were used to highlight the metabolic changes using LC-MS data of the methanolic extracts generated from the two wheat varieties. Molecular networking in Global Natural Product Social (GNPS) was further used to analyse biological networks between the perturbed metabolites. PCA and OPLS-DA analysis showed cluster separations between the varieties, infection races and the time-points. Distinct biochemical changes were also observed between the races and time-points. Metabolites were identified and classified using base peak intensities (BPI) and single ion extracted chromatograms from samples, and the most affected metabolites included flavonoids, carboxylic acids and alkaloids. Network analysis also showed high expression of metabolites from thiamine and glyoxylate, such as flavonoid glycosides, suggesting multi-faceted defence response strategy by understudied wheat varieties towards P. graminis pathogen infection. Overall, the study provided the insights of the biochemical changes in the expression of wheat metabolites in response to stem rust infection.

A “solid” solution for wheat stem sawfly (Hymenoptera: Cephidae) resistance: Genetics, breeding and development of solid stem wheat

AbstractWheat (Triticum spp. L) production needs to be improved to meet the needs of a global population of >9 billion people by 2050. Increasing the productivity of the crop under conditions of abiotic and biotic stress to achieve food security continues to be a challenging proposition. Wheat stem sawfly (WSS) (Cephus cinctus Norton) has been considered as a serious pest of wheat since the late 19th century, causing devastating losses of wheat productivity in the Northern Great Plains of United States and regions of Canada. Developing resistant varieties of wheat that show consistent agronomic performances in varying environments is an effective strategy to manage WSS infestations. To achieve this goal, it is necessary to understand the underlying mechanisms of WSS infestation, damage, subsequent response of the host plant, and resulting yield losses. The review focuses on genetics, breeding, and development of solid stem (SS)‐mediated WSS resistance in wheat since it has been the most effective method of genetic resistance in reducing wheat yield losses. Furthermore, the knowledge gaps that need to be addressed to develop an effective resistant cultivar against WSS are also discussed.

Genomic approaches to enhance adaptive plasticity to cope with soil constraints amidst climate change in wheat.

Climate change is varying the availability of resources, soil physicochemical properties, and rainfall events, which collectively determines soil physical and chemical properties. Soil constraints-acidity (pH<6), salinity (pH≤8.5), sodicity, and dispersion (pH>8.5)-are major causes of wheat yield loss in arid and semiarid cropping systems. To cope with changing environments, plants employ adaptive strategies such as phenotypic plasticity, a key multifaceted trait, to promote shifts in phenotypes. Adaptive strategies for constrained soils are complex, determined by key functional traits and genotype×environment×management interactions. The understanding of the molecular basis of stress tolerance is particularly challenging for plasticity traits. Advances in sequencing and high-throughput genomics technologies have identified functional alleles in gene-rich regions, haplotypes, candidate genes, mechanisms, and in silico gene expression profiles at various growth developmental stages. Our review focuses on favorable alleles for enhanced gene expression, quantitative trait loci, and epigenetic regulation of plant responses to soil constraints, including heavy metal stress and nutrient limitations. A strategy is then described for quantitative traits in wheat by investigating significant alleles and functional characterization of variants, followed by gene validation using advanced genomic tools, and marker development for molecular breeding and genome editing. Moreover, the review highlights the progress of gene editing in wheat, multiplex gene editing, and novel alleles for smart control of gene expression. Application of these advanced genomic technologies to enhance plasticity traits along with soil management practices will be an effective tool to build yield, stability, and sustainability on constrained soils in the face of climate change.

Probabilistic assessment of drought impacts on wheat yield in south-eastern Australia

A risk-based approach is more meaningful to quantify the effects of drought on crop yield given the randomness nature of past drought events, compared to the deterministic approach. However, the majority of these probabilistic studies are conducted at national or global scale to assess the yield loss probability under given drought conditions. There is still a lack of research combining droughts and crop yields in a probabilistic way at a local scale. Moreover, it is unclear how drought threshold triggering yield loss at a given conditional probability will vary in dryland cropping regions. Here, we used wheat yield data from 66 shires in New South Wales (NSW) wheat belt and meteorological data from 986 weather stations. A copula-based probabilistic method was developed to explore the yield loss probability to various drought conditions. We investigated the drought threshold under a given yield loss probability using the constructed copula function. We found that SPEI-6 in October was the optimal drought index to represent detrended wheat yield variation as this period covered the main growth stages of winter wheat in the study region. Our results show that as the severity of drought increased, the wheat yield loss probability also increased. Yield loss probability varied among the study shires, mainly due to the various climate conditions of each region. The drought threshold in subregion 1 (the northwest) was highest, followed by subregion 2 (the southwest) and subregion 3 (the eastern), indicating that wheat yield in subregion 1 was more sensitive to drought. The findings could provide important direction and benchmarks for stakeholders in evaluating the agricultural impact of drought, especially in those drought prone areas. We expect that the methodological framework developed here can be extended to other dryland areas to provide helpful information to growers, risk management policy makers and agricultural insurance evaluators.

Divergent effectiveness of irrigation in enhancing food security in droughts under future climates with various emission scenarios

Food security is a key target in the UN Sustainable Development Goals (SDGs) and is also one of the biggest challenges for China, the largest developing country in population in the world. Massive attention has been directed to the future impacts of hydrometeorological extremes on crop yield. However, knowledge gaps still stand concerning the effectiveness of irrigation, as the largest water consumption sector, on agricultural production under different climate scenarios. Here we showed the drought based on the modified Palmer Drought Severity Index and analyzed the drought-induced wheat yield losses in irrigated and non-irrigated agriculture across China according to three methods including the Multiple Linear Regression method, Deep Learning algorithm, and Erosion-Productivity Impact Calculator model. We found that the droughts become more intensive in the future, and drought-induced wheat yield loss under RCP8.5 scenario was expected to reach 32–49%. Intercomparison of drought-induced wheat yield changes between irrigated and non-irrigated agriculture indicated significantly less drought-induced crop-yield losses given sufficient irrigation under the RCP2.6 and RCP6.0 scenarios. However, our results under RCP8.5 suggested that the effectiveness of irrigation in enhancing food security is minor under this high-emission future climate scenario. These findings allowed us to revisit the effectiveness of irrigation in a warming climate and highlighted the importance of climate change mitigation in food security.

A cell wall invertase modulates resistance to fusarium crown rot and sharp eyespot in common wheat.

Fusarium crown rot (FCR) and sharp eyespot (SE) are serious soil-borne diseases in wheat and its relatives that have been reported to cause wheat yield losses in many areas. In this study, the expression of a cell wall invertase gene, TaCWI-B1, was identified to be associated with FCR resistance through a combination of bulk segregant RNA sequencing and genome resequencing in a recombinant inbred line population. Two bi-parental populations were developed to further verify TaCWI-B1 association with FCR resistance. Overexpression lines and ethyl-methanesulfonate (EMS) mutants revealed TaCWI-B1 positively regulating FCR resistance. Determination of cell wall thickness and components showed that the TaCWI-B1-overexpression lines exhibited considerably increased thickness and pectin and cellulose contents. Furthermore, we found that TaCWI-B1 directly interacted with an alpha-galactosidase (TaGAL). EMS mutants showed that TaGAL negatively modulated FCR resistance. The expression of TaGAL is negatively correlated with TaCWI-B1 levels, thus may reduce mannan degradation in the cell wall, consequently leading to thickening of the cell wall. Additionally, TaCWI-B1-overexpression lines and TaGAL mutants showed higher resistance to SE; however, TaCWI-B1 mutants were more susceptible to SE than controls. This study provides insights into a FCR and SE resistance gene to combat soil-borne diseases in common wheat. Short Summary: A cell wall invertase gene TaCWI was cloned and associated with resistance against Fusarium crown rot and sharp eyespot in common wheat, and an underlying molecular mechanism was proposed, in which TaCWI conferring thickened cell wall counteracts the effects of TaGAL, an alpha-galactosidase gene associated with susceptibility to the two diseases. This article is protected by copyright. All rights reserved.

Effects of Climate Change on Wheat Yield and Nitrogen Losses per Unit of Yield in the Middle and Lower Reaches of the Yangtze River in China

Nitrogen fertilizer is one of the essential nutrients for wheat growth and development, and it plays an important role in increasing and stabilizing wheat yield. Future climate change will affect wheat growth, development, and yield, since climate change will also alter nitrogen cycles in farmland. Therefore, further research is needed to understand the response of wheat yield and nitrogen losses to climate change during cultivation. In this study, we investigate the wheat-producing region in the middle and lower reaches of the Yangtze River in China, one of the leading wheat-producing areas, by employing a random forest model using wheat yield records from agricultural meteorological observation stations and spatial data on wheat yield, nitrogen application rate, and nitrogen losses. The model predicts winter wheat yield and nitrogen losses in the middle and lower reaches of the Yangtze River based on CMIP6 meteorological data and related environmental variables, under SSP126 and SSP585 emission scenarios. The results show that future climate change (temperature and precipitation changes) will decrease winter wheat yield by 2~4% and reduce total nitrogen losses by 0~5%, but in other areas, the total nitrogen losses will increase by 0~5% and the N leaching losses per unit of yield will increase by 0~10%. The results of this study can provide a theoretical basis and reference for optimizing nitrogen application rates, increasing yield, and reducing nitrogen losses in wheat cultivation under climate change conditions.

The impacts of ambient ozone pollution on China's wheat yield and forest production from 2010 to 2021

Near-surface ozone causes damages on both crop and forest but their long-term spatiotemporal changes in China have been insufficiently explored, preventing comprehensive policy making with food security and climate targets. Moreover, limitation exists in the current metrics for long-term regional ozone risk assessment, AOT40 (the accumulated hourly ozone over a threshold of 40 ppbv) and PODY (phytotoxic ozone dose over a threshold of Y nmol ozone m−2 PLA s−1), with ignorance of meteorological influence for the former and complicated data collection and calculation procedures for the latter. Here, we developed a new metric for ozone-induced risk on winter wheat, O3MET, which can be easily derived based on ozone concentrations and meteorological variables, and is suitable for long-term assessment of ozone-induced wheat loss at the regional scale. Combining with existing metric for forest (O3RH), we comprehensively quantified the ozone damages on winter wheat yield and forest gross primary production (GPP) for mainland China during 2010–2021, the period with fast growth of ozone level across the country. The annual average losses of wheat yield and forest GPP were estimated at 26.5 Mt and 552.6 TgC, accounting for 17% and 4% of the total yield and GPP without ozone impact, respectively. Heavy dual ozone-induced damages on both wheat and forest were presented in East and South China. The ozone-induced wheat yield loss and forest GPP loss were estimated to increase at a rate of 1.8 Mt/yr and 13.9 TgC/yr for the entire country, respectively, driven mainly by the enhanced ambient ozone level within the research period. Besides ecological impact, the ozone pollution in the developed eastern China resulted in serious health burden as well, thus effective actions on ozone pollution alleviation in the region is crucial for reducing its ecological and health risks simultaneously.

Control of Multiple-Herbicide-Resistant Canada Fleabane With Fall, Spring, and Sequential Herbicide Applications in Winter Wheat

Limited information exists on the efficacy of pyrasulfotole/bromoxynil, fluroxypyr/halauxifen-methyl + MCPA EHE, and clopyralid applied in the fall, spring, or sequentially [fall followed by (fb) spring] for the control of multiple-herbicide-resistant (MHR) Canada fleabane in winter wheat under Ontario environmental conditions. Three field experiments were initiated in the autumn of 2020 and 2021 for a total of 6 site-years to evaluate fall- and spring-applied herbicides and their sequential applications for the control of MHR Canada fleabane in winter wheat in Ontario. Pyrasulfotole/bromoxynil applied in the fall, spring, or sequentially controlled MHR Canada fleabane 83, 99, and 100%, respectively at 8 weeks after the spring application (WAB); the spring and sequential applications provided better control than the fall application. Fluroxypyr/halauxifen + MCPA and clopyralid applied in the fall, spring, or sequentially controlled MHR Canada fleabane 97 to 100% and 99 to 100%, respectively at 8 WAB. Based on orthogonal contrasts the spring and sequential herbicide applications provided greater control than the fall application (8 WAB). MHR Canada fleabane interference reduced winter wheat yield up to 27% in this study. Based on orthogonal contrasts reduced MHR Canada fleabane interference with the fall application resulted in 17% higher winter wheat yield than when herbicide application was delayed to the spring. Although MHR Canada fleabane was controlled very effectively with clopyralid winter wheat yield was lower, presumably due to crop injury; this observation will have to be explored further in future research. Results from this study indicate that pyrasulfotole/bromoxynil and fluroxypyr/halauxifen + MCPA applied in the fall can be used to effectively control MHR Canada fleabane and minimize winter wheat yield loss due to weed interference.

Dynamic Analysis of Regional Wheat Stripe Rust Environmental Suitability in China

Stripe rust is one of the most destructive wheat diseases in China, negatively affecting the production safety and causing yield losses of wheat. Thus, it is important to analyze the environmental suitability and dynamic changes of wheat stripe rust in China. The occurrence of stripe rust is affected by multiple factors. Therefore, this study combined data from various disciplinary fields such as remote sensing, meteorology, biology, and plant protection to evaluate the environmental suitability of stripe rust in China using species distribution models. The study also discusses the importance and effect of various variables. Results revealed that meteorological factors had the greatest impact on the occurrence of stripe rust, especially temperature and precipitation. Wheat growth factors have a greater impact from April to August. Elevation has a greater impact in summer. The ensemble model results were better than the single model, with TSS and AUC greater than 0.851 and 0.971, respectively. Overlapping analysis showed that the winter stripe rust suitable areas were mainly in the Sichuan Basin, Northwestern Hubei, Southern Shaanxi, and Southern Henan wheat areas. In spring, the suitable areas of stripe rust increased in Huang-Huai-Hai and the middle and lower reaches of the Yangtze River and Guanzhong Plain, and the development of northwestern wheat areas such as Xinjiang and Gansu slightly lagged behind. In summer, wheat threatened by stripe rust is mainly in late-ripening spring wheat areas in Gansu, Ningxia, Qinghai, and Xinjiang. This study can provide a scientific basis for optimizing and improving the comprehensive management strategy of stripe rust.

The use of PI 277012-derived Fusarium head blight resistance QTL in winter wheat breeding

Fusarium head blight (FHB) caused by Fusarium graminearum results in substantial grain yield and quality losses in common wheat (Triticum aestivum L.). Genetic resistance is partial but crucial for effective, integrated management of the disease. Host resistance is conditioned by numerous small effect quantitative trait loci (QTL) that are strongly affected by the environment and genetic background. Qfhb.rwg-5A.1 and Qfhb.rwg-5A.2 (PI 277012 is the source for both genes) are two recently discovered FHB resistance QTL that also occur in spring wheat GP80 (PI 277012 derivative). To transfer the PI 277012 resistance from GP80 to hard winter wheat (HWW), GP80 was first crossed with Novus-4. The F1 hybrid was crossed with SY Monument, following which marker-selected progeny were crossed with, and backcrossed to, ND Noreen. To potential carriers of FHB resistance QTL among the 22 F1 of the ND Noreen cross, simple sequence repeat (SSR) markers, Illumina 90 K single nucleotide polymorphism (SNP) haplotypes and greenhouse FHB Type II resistance tests were done. Likely homozygotes for Qfhb.rwg.5A.1 and Qfhb.rwg.5A.2, were selected and backcrossed to ND Noreen. In the B1F1, 131 plants were evaluated for SNP haplotypes, SSR markers and FHB resistance. Nine B1F2:3 lines were derived, and their resistance confirmed in a third greenhouse FHB trial. The results suggested that eight lines had higher resistance and were comparable to GP80 with the Qfhb.rwg-5A.2 markers occurring in all eight and the Qfhb.rwg-5A.1 markers occurring in four lines. The eight selections constitute a valuable HWW resistance breeding resource.

Molecular evidences for population differentiation and the migration from south to north of Puccinia triticina in eastern China

Wheat leaf rust is caused by Puccinia triticina (Pt), leading to serious wheat yield loss in the world. To study the population structure and reveal the transmission routes of Pt in eastern China, leaf samples were collected from the main wheat-producing areas from April to June 2020. Total of 372 Pt strains were amplified by 13 SSR makers and a high level of genetic diversity was revealed with 289 multi-locus genotypes (MLG) identified. STRUCTURE analysis suggests that all Pt strains were assigned to 3 clusters, and 11 populations were further defined by considering geographic locations. All 55 pairwise populations had number of migration (Nm) values > 1, indicating moderate genetic differentiation and frequent exchanges among populations. The genetic structure was significant different among populations in the northern and southern regions bounded by the Qinling Mountains-Huaihe River line. Pt strains in the southern regions, such as Jiangsu, Anhui and Zhejiang provinces, had higher level of genetic diversity and genetic variation, and Jiangsu might play an important role in the epidemic and population structure of Pt. Both genetic communication and horizontal wind field analyses showed that Pt had higher level of gene flow from the southern to northern regions than that of the reverse direction. The demonstrated genetic structure and dispersal route of Chinese eastern Pt populations would provide valuable information for epidemiological studies and disease control.

Quantifying Wheat Blast Disease Induced Yield and Production Losses of Wheat: A Quasi-Natural Experiment

AbstractApplying the difference-in-difference (DID) estimation procedure, this study quantifies the wheat blast (Magnaporthe oryzae pathotype Triticum) induced losses in wheat yield, quantity of wheat sold, consumed, or stored, as well as wheat grain value in Bangladesh in 2016 following a disease outbreak that affected over 15,000 ha. Estimates show that the blast-induced yield loss was 540 kg ha−1 on average for households in blast-affected districts. Estimated total wheat production loss was approximately 8,205 tons worth USD 2.1 million in during the 2016 outbreak. Based on these insights, we discuss the need for long-term assured investment and concerted research efforts in controlling transboundary diseases such as wheat blast, including the importance of weather forecast driven early warning systems and the dissemination of blast-resistant varieties.

Assessment of photosynthesis and yield loss of winter wheat under ground-level ozone exposure

Assessment of photosynthesis and yield loss of winter wheat under ground-level ozone exposure

Hyperspectral estimation of wheat stripe rust using fractional order differential equations and Gaussian process methods

Wheat stripe rust is the main cause of yield loss in winter wheat. For nondestructive monitoring of wheat stripe rust by remote sensing, a high-precision stripe rust monitoring model can be constructed so that field management can be performed rationally and environmental damage from large doses of pesticides and chemicals can be avoided. Fractional order differential (FOD) equations can be used to flexibly control the differential step size, which enhances the spectral information and reduces the background noise. In this study, the canopy hyperspectral data under the influence of wheat stripe rust were evaluated by FOD, and the disease severity level (SL) of stripe rust in the field was analyzed by evaluating the polar difference, coefficient of variation, and correlation coefficient. Subsequently, the spectral features associated with stripe rust were screened using significance tests and Gaussian process regression sigma (GPR sigma) analysis methods. Then, models for the various wheat stripe rust severity levels were established by Gaussian process regression (GPR) with different data inputs. The results showed that the 0.8–1.4 differential order could effectively improve the correlation between spectral bands and disease severity, and the optimal correlation between the 1.2 order differential spectra and wheat stripe rust severity improved by 15% compared with the original reflectance spectra. The GPR sigma band analysis method screens only 8 bands at order 1.2, the R2 between the model-predicted SL and the measured SL is improved by 13% compared to the original reflectance spectrum, and the RMSE and MAE are reduced by 34% and 39%, respectively. Compared with the significance test method, GPR sigma band analysis selected fewer bands, constructed models with higher accuracy and was more suitable for the construction of models for estimating the severity of wheat stripe rust disease.

Impact of simulated hail damage at different growth stages and canopy positions on rainfed and irrigated winter wheat

AbstractProducers and crop insurance providers will benefit from an accurate assessment of yield reduction after hailstorms that considers crop management, weather, growth stage, and impacted part of crop (hail affected canopy position). But, limited information is available. The main objectives of this study were to quantify wheat (Triticum aestivum L.) yield losses associated with simulated hail damage timing and canopy position. The study was conducted in two locations (Garden City [irrigated], and Manhattan [rainfed]) in Kansas, from 2018 to 2020 and 2016 to 2018, respectively. Treatments were an incomplete factorial combination of stem bending at seven flowering stages, above or below the flag leaf and a nontreated control. Results of the study indicated 11%–22% wheat yield reduction due to simulated hail damage above the flag leaf and 32%–52% due to hail impact below the flag leaf under irrigated conditions. Within the high‐yielding rainfed environment, hail damage caused up to 20% yield reduction compared with the control. In rainfed and low‐yielding environments, the impact of hail damage was mainly dependent on the growth stage of wheat at hail occurrence. Hail damage at Feekes 11.2–11.4 stages decreased yield by 20%–50% from the rainfed control. Hail damage at Feekes 10.0–10.5.4 decreased yield by 50%–70% from the rainfed control. We provide empirical evidence that indicates hail damage on wheat is dependent on the interaction effect of in‐season crop water management, weather, canopy position and crop growth stage, and estimates of yield loss due to hail should consider these factors.

CRISPR/Cas9-guided knockout of eIF4E improves Wheat yellow mosaic virus resistance without yield penalty.

CRISPR/Cas9-guided knockout of eIF4E improves Wheat yellow mosaic virus resistance without yield penalty.

Evaluation of Drought Tolerance in Emmer Based Wheat Double Haploid Lines Using Surrogate Traits and Stress Tolerance Indices

Wheat is one of the major cereals and staple food cultivated worldwide, affected by severe environmental and climate changes. Global warming has led to significant variations in wheat production, accounting for losses up to 6.4% for each 1°C rise in temperature. Recurrent droughts in cultivable areas are anticipated to increase the risk of wheat yield loss by almost 12% by the end of the 21stcentury. The present study was undertaken to identify component traits contributing to drought tolerance and to evaluate wheat doubled haploid (DH) lines for drought tolerance using various stress tolerance indices. Fifty-three wheat DH lines and 11 check varieties were evaluated for grain yield, agronomic, physiological traits and drought tolerance indices under rainfed and restricted irrigation conditions in the 2019-20 cropping season. The results of ANOVA revealed that various yield contributing, agronomic and physiological traits showed highly significant genotypic variation. A significant positive correlation was observed between grain yield under rainfed (Ys) and restricted irrigation (Yp) conditions and geometric mean productivity (GMP), mean productivity (MP), harmonic mean (HM), stress tolerance index (STI) and yield index (YI). Principal component analysis (PCA) showed a significant positive correlation between stress susceptibility index (SSI) and tolerance (TOL). Based on PCA and cluster analysis, the test entries like DH 989 and DH 554, along with check cultivars NI 5439, NIAW 1415, DPW 621-50, were more stable in a rainfed environment while DH 807, DH 430, DH 435, DH 417 and DH 431 were highly adapted to restricted irrigation conditions.DH 66, DH 227,DH 931, DH 62, DH 942 DH 875, DH 134 and DH 179 were identified as susceptible genotypes. Cluster analysis also classified the genotypes into four groups, i.e., resistant, susceptible, tolerant and moderately tolerant to drought conditions. As per our study, few genotypes susceptible to drought exhibited yield reduction while the tolerant genotypes were stable, suggesting their genetic variability and utilization in a breeding program.