Drought Resistance QTL Mapping And Screening Identification Indexes In Sunflower

Sunflower?Helianthus annuus L.?is the second oil crop in the world.Drought is the major cause of yield loss in sunflower and the most economical and effective approach to solve this problem has been directed towards improving drought resistance and developing drought resisitance sunflower varieties.The objective of this study included three parts:?1?Ten sunflower inbred lines were chosen as the research object,the yield?growth?physiological characteristics were investigated under both water stress and irrigation conditions at the florescence and the grey correlation analysis method were used to screen identifcation indexes of drought resistance to establish the sunflower drought resistance identificant system.?2?In this study,SNP?SSR with originalSSR?EST-SSR?SRAP and AFLP markers were applied to construct a genetic linkage map by using the F₇population derived from a cross of K55?drought sensitive??K58?drought resistance?,nine traits treated with water stress and irrigation were mapping quantitative trait loci?QTLs?on it.?3?A drought-tolerance population of 45 BC₃F₂lines were constructed and seven yield traits were used to QTL mapping through Chi-square test and one-way ANOVA.The QTL may lay a foundation for molecular marker-assisted selection.The main results were as follows:1.All of 18 drought resistance related indexes measured were sensitive to drought stress.According to the results of grey correlation analysis method,9 indexes selected including relative fill seed number?relative seed yield?relative root shoot ratio and so on,these 9 indexes could be used to assess the drought resistance of sunflower at the florescence.2.A genetic map consisting of 17 linkage groups was constructed with 4932 loci including 3929 SNP?294 SSR?39 EST-SSR?317 AFLP?353 SRAP which covers 2111.78cM and the length of each linkage group varies from 77.29 to 185.79 cM,the number of markers in each linkage group varies from 74 to 665 with an average distance of 0.43 cM.There were 18 gaps more than 10 cM and 97%of group gaps were less than 5 cM.A total of 225 markers that on the groups showed segregation distortion and distributed in group1?5?7?9?17.3.The QTL of 9 traits including plant height?leaf area?SPAD,et al.were detected under two water treatments for RILs,a total of 25 QTLs were observed and distributed in group 4?5?8?11?13?14?16 and 17,could explaining the phenetic variation from 6.3%to 13.5%.A total of 15 QTLs were detected under water stress treatment,of which 2 QTLs controlled leaf area,3 QTLs controlled leaf water holding,7 QTLs controlled setting ratio,1 QTLs controlled SPAD value?hundred seed weight?stem diameter,respectively.A total of 10 QTLs were detected under irrigation treatment,of which 4 QTLs controlled leaf water holding,2 QTLs controlled stem diameter?hundred seed weight,respectively,1QTLs controlled leaf area and SPAD value,respectively.There 2 QTLs?Qla16-2?Qlwh11?were detected under both two water treatments,9 QTLs could explain phenotypic contribution over 10%.4.There 7 yield traits including seed yield?fill seed number?setting ratio,et al.were measured under two water treatments of Hohhot and WuChuan for drought-tolerance population.A total of 235 QTLs were detected by using one-way ANOVA method.There76 QTLs were detected under two water treatment in Hohhot,of which 43 QTLs were detected under water stress treatment and 53 QTLs were detected under irrigation treatment;There 139 QTLs were detected two water treatments in WuChuan of which 69QTLs were detected under water stress treatment and 70 QTLs were detected under irrigation treatment.There 164 QTLs the value of the add were plus and the loci increasing the yield come from the donor parent;71 QTLs the value of the add were negative and the loci increasing the yield come from the recurrent parent.There were 13 QTLs were detected in one water treatment at two locations;6 QTLs were detected under both two water treatment at two locations respectively,3 QTL were detected under one more water treatment conditions both at two locations.There 3 QTLs clusters were detected in total.5.QTL mapping through Chi-square test for drought-tolerance population detected275 segregation distortion locis?P<0.005?,the max?2 was 70.86,these QTLwere all related to drought resistance.6.A total of 18 QTLs were both deteted between one-way ANOVA method and Chi-square,these QTLs were important to drought resistance.