| Common bean?phaseolus vulgaris L.?is one of the most important edible beans,which are characterized by high nutritional value and are favored by consumers.In China,the average annual planting area of common bean is about 800 thousand hm2,of which is arid and barren area.Improving the adaptability of common bean to drought environment is one of the important breeding objectives which breeders have long adhered to.Therefore,it is necessary to select drought resistant resources for using by breeders,and in order to improve the utilization efficiency of drought resistant resources,the resistant sites/genes should be identified on a large scale to enhance the level of molecular breeding.In the present study,644 common bean core germplasms were evaluated for drought resistance at different growth stages,selecting drought resistant resources.Based on this,genome-wide association analysis was used to identify important loci/genes associated with drought resistance,the main results were as follows:1.Screening the drought-resistant resources of common bean at bud and seedling stageThe PEG-6000 solution was used to simulate the drought stress at bud stage,evaluating the two germination traits including relative germination vigor and relative germination rate,and nine root traits including relative root length,relative root dry weight and relative total root length so on.Using the membership functions to comprehensively analyze the 11 traits,ten drought-resistant resources were selected,such as Fandou?F0000452?,Xiaofandou?F0000134?,and Liushirizao?F0001932?;using repeated drought methods to investigate repeated drought survival rates for evaluating the drought resistance of common bean at seedling stage,23 high-resistant resources were selected,such as green beans?F0005830?,Jiaquedan?F0002471?and Baiyundou?F0002509?.The results of comprehensive drought evaluation at bud and seedling stage showed that Hongyaozidou?F00002625?showed high drought resistance at both growth stages.2.Identifying drought resistant loci/genes by genome-wide association analysisUsing genome-wide association analysis to identify the relevant loci associated with 11 traits at bud stage based on 4811106 SNP markers,a total of 479 significant loci distributed on 11 chromosomes were detected,of which 205 loci were associated with relative lateral root length,and only 10 loci were detected in relative lateral root number;further analysis showed that 128 loci were significantly associated with at least 3 traits,of which 7 loci were significantly associated with 6 traits;twelve significant loci were detected at seedling stage,of which the locus SS10 located at on chromosome 11(P=4.36×10-8)were stably detected in three replicates;the results of comprehensive analysis at bud and seedling stage showed that 11 loci were detected stably at both growth stage.3.Analysis of drought resistant related candidate genesAmong the loci detected at bud stage and seedling stage,the significant loci associated with relative root dry weight,relative special root length,and relative total root length so on,were coincided with the previously reported significant loci using linkage analysis;the analysis results of the genes near the 11 loci that were stably detected at both growth stages indicated there were transcription factors such as WRKY,NAC,ERF,MYB;some homologous genes related drought resistance have been confirmed in other crops.Among them,there was a CDPK gene located at near Chr0244293383(P=1.25×10-7)on chromosome No.2,it's homologous gene AtCDPK2 in Arabidopsis thaliana has been reported to inhibit root growth and increased sensitivity to drought;there was a senescence-related gene located at near the Chr0745797752(P=6.96×10-8)on chromosome No.7 chromosome,it's homologous gene AtLEA5 in Arabidopsis thaliana has been reported to affect root development and associated with drought resistance. |
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