| Wheat is an important food crop in the world,and it is widely planted in China.However,due to climate change,uneven spatial and temporal distribution of water resources,industrial pollution and other factors,wheat is seriously short of water during the whole growth and development period,which results in the reduction of wheat production.Therefore,it is one of the main task of wheat breeding to study the relationship between related traits and drought resistance,to explore the markers closely linked with drought resistance traits,and to cultivate new drought resistance and water-saving varieties.In this study,a recombinant inbred line(RIL)consisting of 173 lines derived from a“Shannong01-35×Gaocheng9411”cross were used as materials to measure the morphological indexes and physiological indexes of wheat germination under control condition and drought stress.Principal component analysis and membership function were used to select drought resistance indexes.Comprehensive drought resistance coefficient(D value)was used for comprehensive evaluation of drought resistance.QTL analysis was carried out on the tested traits to identify molecular markers associated with drought resistance traits,so as to provide references for the study of drought resistance mechanism and gene discovery of wheat.The main results were as follows:1.Phenotypic variation analysis showed that under control condition and drought stress,the variation coefficient of only 4 traits was less than 10%.The coefficient of variation of SWLR and RWLR in the two environments was less than 10%,and the coefficient of variation of RFW,SS and Pro was more than 20%.The coefficient of variation of Pro was the highest in the two water environments,indicating that this population had great selection potential.2.The results of correlation analysis showed that SH,MRL,SFW,RFW,SDW,RDW and other morphological indexes were significantly correlated with each other in the twoenvironments.There were also significantly or very significantly correlations between SS and SDW,SWLR;Pro and RFW.3.Principal component analysis and comprehensive evaluation of drought resistance:fourteen drought-related indexes were summarized into four comprehensive indexes by principal component analysis,namely,biomass,root growth factor,SS and CL,with a cumulative contribution rate of 74.65%.The above comprehensive indexes can be used as reference indexes for the later drought resistance evaluation of wheat.The comprehensive evaluation results indicated that: the drought resistance of 11 lines was the strongest,127 lines were average and 28 lines were poor.The comprehensive drought resistance coefficient of line 143 was the lowest(0.152),indicating that it had the worst drought resistance.The comprehensive drought-resistance coefficient of line 136 was the highest(0.757),indicating that it had the strongest drought-resistance and could provide basic materials for subsequent drought-resistance breeding.4.QTL mapping for drought-resistant traits: this study conducted QTL mapping for morphological and physiological indicators such as SH,CL,MRL,SFW,RFW,SDW,RDW and SS at the seedling stage of wheat.A total of 25 QTL loci were detected,distributed on 11chromosomes(1A,1B,2B,2D,3A,4B,5B,6A,6B,6D and 7B),explained the phenotypic genetic variation ranged from 6.014% to 10.741%.Fifteen QTLs were detected under drought conditions,and ten QTLs were detected under control conditions.The additive effect of 14 QTLs was derived from the maternal Shannong01-35,and 11 QTLs were derived from the paternal Gaocheng9411.QSH2 D.3-60 and QRFW2 D.3-60 are the QTL loci detected on 2D chromosomes that control both SH and RFW,and the genetic contribution rates are 6.904%and 8.711%,respectively.QRWLR5 B.4-47 is the main QTL locus controlling RWLR,which can explain 10.741% of the phenotypic variation.5.Conditional QTL analysis for drought-resistant traits: using the trait values under control condition as the given conditions,the conditional QTL mapping for various indicators in the emergence stage of wheat was conducted,and a total of 13 conditional QTLs were detected.Among them,5 QTLs were detected in both conditional and unconditional QTL analysis,indicating that these loci were affected by water stress.Eight new QTLs were onlydetected in conditional QTL analysis,indicating that these QTLs may be important loci for controlling traits. |
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