| Drought is one of the most serious adversities constraining agricultural production.Due to the global climate,drought and other extreme weather are frequent,which has brought great threats to food production in China and even the world,and brought great pressure to food security.Wheat is the most widely planted crop in the world,and its sustained high yield and stable yield are of great significance to ensure food security in China and the world.Excavating and utilizing the drought resistance gene of wheat and cultivating new wheat varieties with synergistic improvement of drought resistance and yield are not only an inevitable requirement for promoting high-quality and sustainable development of wheat production,but also an urgent need to ensure world food security.In view of this,this study used the recombinant inbred group constructed by the hybridization of the strong droughtresistant variety Jinmai 47 and the high-yield and high-quality variety Yanzhan 4110 as the material,combined with the indoor hydroponic identification of drought resistance and field agronomic investigation,and systematically evaluated and identified its drought resistance,based on multi-trait analysis and excavation of excellent drought-resistant germplasm.On this basis,the genetic model analysis of each trait was carried out,and the genetic model and gene number of each trait were analyzed,and the genetic basis of drought resistance was preliminarily clarified.Finally,based on the 55 K SNP chip genotyping,the QTL localization of drought resistance was carried out,the results of genetic model analysis were verified,and the QTL related QTLs and candidate genes related to wheat drought resistance were mined,in order to lay a foundation for the genetic improvement of wheat drought resistance.The main results achieved are as follows:(1)The "Jinmai 47/Yanzhan 4110" RIL population composed of 142 strains was used as materials,and the drought resistance at the seedling stage was systematically identified indoors.By investigating 10 traits such as fresh weight,root fresh weight and root length under normal control and PEG simulated drought stress,and comparing and analyzing them,it was found that all traits under drought stress were significantly smaller than those under control conditions,and drought had a significant inhibitory effect on wheat growth and development.The coefficients of variation of root volume were the largest under control conditions and drought stress,50.3% and 68.8%,respectively,the coefficient of variation of root mean area under control conditions and the smallest coefficient of variation of seedling height under drought stress was 12.7% and 13.8%,respectively.The four biomass traits,such as dry weight and fresh weight of seedlings,showed a significant positive correlation between them under both conditions.There were also significant positive correlations between root surface area and root volume,and between average root diameter and root volume.(2)Based on 10 phenotypic traits,the drought resistance coefficient of each strain was calculated,and the principal component analysis of the drought resistance coefficient of 10 traits was carried out,and the 10 drought-related traits were transformed into four independent comprehensive indicators: biomass index,root volume index,root average diameter index and seedling height index,and these four indexes were determined as relevant indicators for identifying the drought resistance of wheat,and a drought resistance identification method based on multiple indicators was constructed based on the membership function,and the comprehensive evaluation coefficient of drought resistance ability of each strain was further calculated.The variation range ranged from 0.185 to 0.789,and the average value was 0.388,and the correlation analysis between each trait and the comprehensive evaluation coefficient of drought resistance showed that root fresh weight,root dry weight,plant height,plant fresh weight,plant dry weight,root length,root surface area,root volume and the comprehensive evaluation value of drought resistance were very positively correlated,which could be used to evaluate the drought tolerance of wheat,and five strong drought-resistant families: RIL304,RIL298,RIL294,RIL288 and RIL302 were screened..(3)The genetic model analysis of "Jinmai 47/Yanzhan 4110" RIL population wheat under two environmental conditions showed that wheat seedling height was controlled by two pairs of main genes and polygenes under control conditions,and polygenic control under drought conditions.The dry weight of wheat seedlings was controlled by two pairs of main genes under control conditions,and by two pairs of main genes and polygenes under drought conditions.Wheat root growth was controlled by two pairs of master genes under both conditions.The dry-weight root-to-root ratio of wheat was controlled by two pairs of master genes under control conditions and polygenic control under drought conditions.The root surface area of wheat was controlled by four pairs of master genes under control conditions,and three pairs of master genes and polygenes under drought conditions.The dry weight of wheat roots and fresh weight of seedlings were controlled by two pairs of main genes under control conditions and four pairs of main genes under drought conditions.Wheat root volume and root surface area were controlled by three pairs of master genes and polygenes under both conditions.The average diameter of wheat roots was controlled by two pairs of master genes under control conditions and three pairs of master genes and polygenes under drought conditions.(4)The 55 KSNP chip was used to genotype each strain,2111 polymorphic SNP markers were obtained,the genetic map was constructed,and QTL localization was performed based on the above agronomic phenotypes.The results identified 19 QTL sites,which were distributed on 11 chromosomes of 1A,1B,1D,3A,3B,4D,5A,6A,6B,6D and 7B,including11 QTL sites detected under normal conditions,8 QTL sites detected under simulated drought conditions,and 1 site related to the comprehensive evaluation coefficient of drought resistance,which were basically consistent with the results of genetic model analysis.Among them,4QTLs are the main QTLs,and 11 QTLs form 4 chromosome clusters,which are distributed on chromosomes 1A,3A,6A,and 7B.(5)Finally,the integration of drought-resistant phenotyping and QTL localization results proves that the drought-resistant traits of Jinmai 47 have a complex genetic basis,involving multiple chromosomes and gene interactions.Under drought conditions,the five favorable alleles provided by Paternal Jinmai 47 included one seedling height-related QTL(QSh-3A),one seedling stem weight-related main QTL(QSdw-3A),one root lengthrelated QTL(QTrl-3B),and two root mean area-related QTLs(QRad-5A1,QRad-6D),and also had a main QTL(QDv-4D)that regulated the D value of the comprehensive drought resistance evaluation coefficient.It laid a foundation for the subsequent in-depth analysis of the genetic basis of drought resistance of Jinmai 47 and the mining of key drought resistance genes.In this study,the drought resistance of wheat 47/Yanzhan 4110 RIL population was systematically evaluated and identified,and the genetic effects and genetic basis of drought resistance were preliminarily analyzed by combining genetic models,QTL positioning and field agronomic traits and grain traits,which laid a foundation for further identification and cloning of key genes of drought resistance and the molecular mechanism of drought resistance formation,and also provided theoretical and technical support for the genetic breeding of wheat drought resistance. |
PDF Full Text Request