| Wheat(Triticum aestivum L.)is one of the most important food crops worldwide,playing an indispensable role in addressing global food supply and ensuring national food security.Drought resistance is one of the most important resistances of wheat.The scientific identification of drought resistance in wheat,screening of drought resistance indicators that can reflect the drought resistance of wheat,and analysis of the response mechanisms of wheat under drought stress,as well as the exploration of genes related to drought resistance,can help accelerate the breeding process of drought-resistant wheat.The main research results are as follows:1.Selection of drought-resistant indicators and identification of drought resistance in wheat during the maturity stage.second leaf width,peduncle length,spikelet number,biomass,and grain yield.Furthermore,it has been observed that the agronomic traits contributing the most to drought tolerance in wheat are grain yield,biomass,spikelet number,and thousand grain weight.Therefore,improving drought resistance through increased spikelet number and thousand grain weight,while ensuring a certain number of effective spikes,is beneficial for breeding drought-tolerant and high-yielding wheat varieties.During the period of 2020-2021,5 high-generation material lines with small stature and drought resistance,such as XN223/Rht13,were identified.In the period of 2021-2022,the high-generation material Fengai 14/Q-4-1 was identified as having high drought resistance.2.Feasibility of Wheat Seedling ABA Response as an Indicator of Drought Resistance.The main effects of exogenous ABA stress on wheat seedlings include: reduced leaf fresh weight,shortened leaf length,promoted root elongation,increased root weight,resulting in an increased root-to-shoot ratio in wheat.Furthermore,it was found that the tolerance to ABA in terms of fresh weight-to-root-to-shoot ratio at the seedling stage was significantly positively correlated with drought resistance indices in wheat at the mature stage,under 15 μM ABA concentration stress.Therefore,the tolerance of fresh weight-toroot-to-shoot ratio to ABA can be used as an indicator for drought tolerance identification in wheat seedlings under 15 μM ABA concentration stress.Selection of wheat germplasm for tolerance to ABA stress during the seedling stage:The experiment calculated the ABA tolerance coefficient of fresh weight root-to-shoot ratio for 197 wheat varieties and performed cluster analysis.As a result,9 wheat materials with high tolerance to ABA,such as Xiaoyan 22,were selected.3.Transcriptome analysis of wheat under ABA stress.After ABA stress,a total of 3520 DEGs were identified in the leaves of the ABAtolerant wheat variety Jinmai 47,while 3707 DEGs were identified in the leaves of the ABAsensitive variety Zhengmai 366.In the roots of Jinmai 47,3648 DEGs were identified after ABA stress,while 783 DEGs were identified in the roots of Zhengmai 336 under ABA stress.The experiment found that the roots of the ABA-tolerant wheat variety Jinmai 47 exhibited stronger positive regulatory abilities in terms of response to stimulation and defense response,but lower negative regulatory abilities in terms of oxidative stress.KEGG pathway enrichment analysis revealed that the differentially expressed genes between ABAtolerant and ABA-sensitive varieties,both before and after ABA stress,were mainly enriched in phenylpropanoid biosynthesis and plant hormone signal transduction pathways.Furthermore,the roots of ABA-tolerant varieties had far more genes involved in plant hormone signal transduction compared to the ABA-sensitive varieties,which may be an important factor contributing to the differences in ABA stress tolerance among different wheat varieties. |
