Genetic Dissection Of Post-anthesis Fructan Metabolism And Remobilization In Wheat Stems And Leaves Regulated By Drought Stress

Fructan is main form of the water soluble carbohydrates in the vegetative organs of wheat.Under drought stress,leaf senescence and photosynthesis were blocked,and temporary stored fructan stored in stem and leaf at the pre-anthesis,functioning as a major carbon source,can effectively compensate for grain filling,but the molecular genetic mechanism of its metabolism and transport was not clear.Therefore,in this research,the Introgression lines?BC₃F₄?derived from 1 set of Xifeng 20 and Jinmai 47 was used.Under the drought and well watered stress,the temporal spatial differences of fructan accumulation and transportion in wheat stem and leaf at the post-anthesis related to phenotypic traits?fructan content,contribution rate at the pre-anthesis,contribution rate at the post anthesis,remobilization rate at the pre-anthesis,remobilization rate at the post anthesis?was analyzed,and QTL mapping and genetic analysis of target traits were carryied out,the results are as follows:1.At post-anthesis stages,the phenotypic variation of stem and leaf fructan accumulation and transport traits of the Wheat ILs population was extensive,showing 18.69%⁷9.29?DS?and 10.74%⁵8.09%?WW?.The phenotypic diversity index ranged from DS?0.44⁰.89?and WW?0.43⁰.84?.Heritability varied between 0.29⁰.67?DS?and 0.29⁰.63?WW?.Fructan content was iinfluenced by developmental stage,organ,interaction effect between them.The remobilization rate and grain contribution rate of fructan were significantly affected by water and organs.2.A total of 442 polymorphic SSR markers were screened in the ILs population.Each polymorphic SSR marker showed 0.31 of the average genetic diversity index?H'?and 0.25 of the average polymorphism information?PIC?.Among them,H'and PIC of the B genome and the third homologous group were higher,while the D genome and the first homologous group were lower.Using cluster analysis,160 strains of this population were classified into five groups.The genetic linkage maps covering 21 chromosomes was contructed by polymorphism SSR markers,which showed about 5,587.39 cM in the total length of the map.And the average length of each chromosome and the average intervals between markers was277.27 cM and 13.25 cM,respectively.3.QTL mapping was performed for all target traits of ILs population,and a total of 82additive QTLs distributed on 19 chromosomes except 1A and 5D,which associated with fructan metabolism and remobilization were found,explaining 0.02%¹6.08%of phenotypic variation.A total of 122 pairs of epistemic QTLs distributed on 21 chromosomes,controlling fructan metabolism and remobilization were detected,and the contribution rate of epistemic effect to phenotypic variation was 0.76%¹4.11%.The significant interaction between additive?A?and epistatic?AA?QTLs and water environment?E?was detected,which could explain 0.01%¹8.08%of phenotypic variance?H²?AE/AAE??indicating that epistasis interaction acted as the the genetic factors controlling this trait.4.A total of 14 main QTLs were detected for fructan accumulation and transportation in wheat,distributed on chromosomes 1D,2A and 2B,which were unevenly distributed in different marker regions.There are many A-QTL hot-spot for the same trait or different trait were also found in some specific intervals.Among them,the marker intervals Xgwm311-Xgwm294 and Xgwm95-Xgwm473.2 on chromosome 2A,Xbarc327-Xwmc219on chromosome 4A,Xwmc74-Xwmc457 on chromosome 4D,Xwmc759-Xwmc740 on chromosome 5B,Xwmc145-Xmag1470 on chromosome 6A,Xmag1134-Xcnl105,Xcfa2040-Xmag1475 and Xmag353.1-Xmag1231 on chromosome 7B.It indicated that it could exist“pleiotropism”sites.In this study,a genetic linkage map of ILs population was developed to identify quantitative trait loci and to dissect genetic base of fructan accumulation and transportation in wheat stem and leaf at the post-anthesis related to phenotypic.The result indicated that epistasis and water interaction was the major genetic factor controlling phenotypic variation of fructan accumulation and transportation related trait.The major QTLs and hot-spot regions would provide theoretical basis for the molecular genetic improvement in drought resistance of wheat.