| Soybean(Glycine max)is an important food and oil crop in the world.In recent years,during the spring sowing in northeast of our country,the drought frequently occurred,which led to the poor germination quality and low emergence rate of soybean seeds.Breeding tolerant varieties is an effective way to deal with drought stress in soybean bud stage.Identification of drought-tolerant germplasm resources and exploitation of drought-tolerant genes will provide high-quality materials for soybean breeding and lay a theoretical foundation for the analysis of genetic mechanism of drought-tolerance.In this experiment,258 soybean Polyethylene glycol from home and abroad are tested for drought tolerance at bud stage by using 20% PEG-6000 to simulate drought stress,germination potential,germination rate,germination index,relative germination potential,relative germination rate,relative germination index and drought injury rate are used as identification indexes,finally,the drought tolerance and sensitive materials are selected by membership function and cluster analysis.Using wild soybean cultivar ZYD00006 as the donor parent and soybean cultivar Suinong14(SN14)as the recurrent parent,a chromosome segment substitution line(CSSL)population was constructed Gene annotation,inter-parental amino acid sequence analysis,promoter cis-element analysis,gene expression analysis and haplotype analysis are used to predict drought-tolerant candidate genes in soybean.The results are as follows:1.There is significant difference between drought stress and control.Membership function is positively correlated with each index,and drought injury rate is negatively correlated with other indexes.According to the subordinate function,258 germplasm resources are divided into4 categories: drought-tolerant germplasm resources 9 varieties(lines);sensitive germplasm resources 8 varieties(lines);sub-sensitive germplasm resources 186 varieties(lines);There are55 varieties(lines)of secondary drought-tolerant germplasm resources.By cluster analysis,258 materials are classified into 3 categories: Resistant Materials(17),intermediate materials(99)and sensitive materials(142).There is no significant difference in the membership function among the 5 regions with different provenances.2.In CSSL population,ICIM is used to map qtls for germination potential,germination rate,germination index,relative germination potential,relative germination rate and relative germination index under drought stress,q GE-4-1 and q GR-15-2 are located on the Chr.04 and Chr.15,and their phenotypic contribution is high.3.qGE-4-1 and q GR-15-2 are co-annotated into 17 genes,17 genes are sequenced and analyzed for their promoter cis-elements.There are variations in amino acids in 5 genes and in CIS elements in 4 genes.According to the results,Glyma.04G100500,Glyma.15G196400,Glyma.15G196500,Glyma.15G196600 and Glyma.15G197000 are identified as drought-tolerant candidate genes in soybean.4.The results of fluorescent quantitative PCR showed that the relative expression of Glyma.15G196400 in the resistant materials is always higher than that in the sensitive materials from 0h to 48 h.Based on the relative expression level of each candidate gene and the variation of its sequence and coding protein in the parents,it is inferred that Glyma.15G196400 may be related to drought tolerance at sprouting stage.5.Haplotype analysis of candidate gene Glyma.15G196400 showed that there are two excellent haplotypes Hap-1 and Hap-3.12 SNP are found in the two excellent haplotypes Hap-1and Hap-3,resulting in cis-variant promoter including CAAT-box promoter.GR of the two excellent haplotypes is significantly different at P < 0.05 level,the results indicated that the candidate gene have wide applicability in soybean population... |
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