低磷胁迫下陆地棉苗期根生物量相关性状全基因组关联分析

Genome-wide association study of root biomass related traits at seeding stage under low phosphorus stress in cotton(Gossypium hirsutum L.)

磷(phosphorus,P)是植物生长发育所必须的营养元素,低磷胁迫是制约棉花生长发育的重要因素之一。本研究以419份陆地棉核心种质为材料,对低磷胁迫下2个环境6个根生物量相关性状进行表型鉴定,基于366万个SNPs(single nucleotide polymorphisms)进行全基因组关联分析(genome-wide association study,GWAS),筛选显著关联的SNPs位点并挖掘候选基因。结果表明,低磷胁迫下棉花根生物量性状具有广泛的遗传变异,其中根冠比(root shoot ratio,RSR)的变异系数最大(45.30%)。在2个环境下共检测到393个与根生物量性状显著关联的SNPs,这些位点主要分布于D02(75个)、A08(64个)和A07(35个)染色体,其中28个SNPs在至少2个性状或环境中同时检测到。进一步筛选到13个候选基因,其中Gh_A08G1889在E1环境中低磷条件下的根冠比(LP-RSR-E1)中检测到,A08:99606874(A/C)位于该基因外显子中并导致了非同义突变(Val/Leu),且该基因编码赤霉素响应蛋白GID1C(Gibberellin receptor GID1C),有报道称该基因与DELLA蛋白相互作用参与赤霉素调节途径,控制植物根部生长发育并响应环境胁迫;Gh_D08G2527在E2环境中低磷条件下的地下部干重和总干重(root dry weight,RDW;total dry weight,TDW;LP-RDW-E2和LP-TDW-E2)中共同检测到,该基因编码的DREB3(Dehydration-responsive element-binding protein 3)类转录因子在多种作物中参与了环境胁迫的响应过程,且DREB可特异性的与DRE结合,诱导环境胁迫响应基因的表达进而使植株产生抗逆性。qRT-PCR结果显示,低磷处理后Gh_D08G2527的表达量在耐低磷品种中显著高于低磷敏感品种。本研究结果为深入了解棉花耐低磷胁迫的分子机制提供了理论参考及基因资源。

Phosphorus(P)is an essential nutrient element for plant growth and development.Low phosphorus stress is one of the important factors restricting the growth and development of cotton.In this study,419 core accessions of upland cotton were used as test materials.Phenotypic identification of six root biomass related traits at the seedling stage in two environments were carried out.Genome-wide association study was used to screen the significantly associated SNPs(single nucleotide polymorphisms)and candidate genes with 3.66 million SNPs.The results showed that there were extensive genetic variations in root biomass traits of cotton under low P stress,among which the coefficient of variation of root shoot ratio was the largest(45.30%).A total of 393 SNPs were significantly associated with root biomass traits,and these loci mainly distributed in chromosome D02(75),A08(64)and A07(35),among which a total of 28 SNPs were detected in two traits or environments at least.13 candidate genes were fur-ther screened,among which Gh_A08G1889 was detected in the RSR under low phosphorus conditions in E1 environment(LP-RSR-E1),and A08:99606874(A/C)was located in the exon of this gene,leading to non-synonymous mutation(Val/Leu).Moreover,the gene encoding protein GID1C(Gibberellin receptor GID1C)can interact with DELLA protein to participate in the GA metabolic pathway,which can control the growth and development of plant roots and respond to environmental stress.Gh_D08G2527 was detected in both root dry weight(RDW)and total dry weight(TDW)in E2 environments(LP-RDW-E2 and LP-TDW-E2).The DREB3(Dehydration-responsive element-binding protein 3)transcription factors encoded by this gene were involved in the response process of environmental stress in a variety of crops,and DREB could specifically combine with DRE to induce the expression of environmental stress response genes and produce plant stress resistance.The results of qRT-PCR revealed that the relative expression of Gh_D08G2527 in low phosphorus tolerant varieties was significantly higher than that in low phos-phorus sensitive varieties under low phosphorus treatment.These results of this study provide theoretical reference and genetic resources for further understanding the molecular mechanism of low phosphorus stress in cotton.