| Common bean is one of the most important food legumes with the largest consumer group,the most widely planting area and the greatest cultivation area in the world,which was characterized by rich nutrition and favored by consumers.However,approximately 60% of common bean-producing areas around the globe suffer from different degrees of drought stress.In China,the planting area of common bean was about 0.74 million hectares,which mainly distributed in barren and arid region restricted the development of common bean production.Therefore,it is the most urgent task to excavate drought-resistant germplasm resources/gene resources and apply them to drought-resistant genetic improvement.In this study,210 determinate growth-common bean were used as experimental materials,and phenotyped for the agronomic traits under well-watered and drought stress environments to screen the drought resistance materials at the adult stage;genome-wide association studies were conducted to explore the drought resistance related genetic loci and genes at adult stage;the drought resistance mechanism of drought related candidate genes was analyzed in the seedling stage,and the main results were as follows:(1)screening drought resistance-common bean accessions at adult stageA total of 210 common bean accessions were phenotyped for 13 agronomic traits at field conditions,including relative seed yield per plant,relative number of days to maturity,relative number of pods per plant,relative number of seeds per plant and relative harvest index so on.Integrating the drought resistance coefficient,drought resistance index and average membership function,twelve high drought tolerance materials were selected,including Naihuayundou,Baicaidou,ISB-82-865,VIVA,Longyundou No.7,SEN13,Bayuezhadouzi,Dahongjindou and Yundou so on;additionally,twenty high drought sensitivity materials were selected.(2)detecting drought resistance loci or genes at adult stageGWASs were conducted based on 4,811,106 SNPs and 13 agronomic traits,and a total of 59 loci contained 86 candidate SNPs were detected which distributed on all chromosomes except Pv06 and Pv07.Among these loci,36 loci were associated with RSW,while there are not significant loci identified to associate with RDF and RTB;further analysis showed that 5 loci were associated with more than one trait,in which Locus＿20 was associated with RPHI,RSY and RDM,Locus＿28 associated with RPL,RSY,RNSP,RSYP and RDM;16 loci identified in this study were found to collocate with drought-related QTL previously reported;a total of 210 potential candidate genes were found in all loci,including genes which encode NAC,MYB,WRKY,protein kinases,phosphatases, receptor proteins,G proteins,transmembrane proteins and functional enzymes,of which 44 genes were reported to associated with water stress in Arabidopsis thaliana,in particularly,Phvul.001G205900 at Locus＿20 encodes TSPO related protein,whose homologs was induced by osmotic stress and ABA in Arabidopsis thaliana,and Phvul.001G205900 was significant induced by drought stress.(3)functional investigation for drought resistance candidate gene at seedling stagePv XIP1;2 was identified from the results of GWAS for drought resistance in common bean at seedling stage;expression pattern analysis showed that Pv XIP1;2 was expressed in all tissues of common bean and induced by drought,salt,osmotic and ABA stresses;Pv XIP1;2 overexpression Arabidopsis thaliana had higher survival rate,proline content and root growth rate,and lower MDA content and membrane system damage under stresses;Hairy root test showed that Pv XIP1;2 can enhance the resistance of common bean to mannitol,indicated that Pv XIP1;2 played an active role in drought response of common bean. |
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