缺铁胁迫对小麦苗期叶绿素含量的影响及SPAD值的GWAS分析

Effects of Iron Deficiency Stress on Chlorophyll Content and GWAS Analysis of SPAD Value in Wheat Seedling Stage

小麦叶绿素含量与产量密切相关,而SPAD值与叶绿素含量呈显著正相关。本文以保存的189份山东省小麦种质资源为研究对象,测定缺铁胁迫下小麦苗期叶片的SPAD值,并进行全基因组关联分析(GWAS)。结果表明,正常培养条件下,SPAD值均值为39.18,变幅为28.33~48.19;缺铁胁迫条件下,SPAD值均值为3.56,变幅为0.07~12.87;胁迫指数均值为-90.89,变幅为-99.83^-68.06,品种间存在极显著差异。利用可变类平均法进行系统聚类,欧式距离为10时,可划分为5大类群。根据不同类群缺铁胁迫SPAD值和胁迫指数的变化特点,供试小麦材料可分为铁耐受型、中间型和敏感型。全基因组关联分析结果显示,在正常处理下,检测到与SPAD值显著关联的SNPs位点23个,分布于1A、2A、2D、3A、3B、4A、4B、4D、5A、5D、6A、6B、6D和7B等染色体上,其中在3B染色体上检测到4个显著的SNPs位点,可能存在与叶绿素含量相关的基因。对于铁耐受型小麦材料的利用,有助于小麦产量和适应性相关性状的遗传改良;对关联SNPs位点的深入研究,有利于深入了解铁与小麦叶绿素合成和调控的遗传机制。

The content of chlorophyll in wheat is closely related to yield,while soil plant analyatical development（SPAD） value is positively correlated with chlorophyll content.In this research,189 wheat germplasms from Shandong Province were selected as the research objects,the SPAD value of leaf blade at seedling stage was determined and the genome-wide association analysis（GWAS） was also carried out.The results showed that under normal culture treatment,the SPAD value ranged from 28.33 to 48.19 with a mean value of 39.18.Under iron deficiency treatment,the SPAD value ranged from 0.07 to 12.87 with a mean value of 3.56.The stress index（SI） ranged from -99.83 to -68.06 with a mean value of -90.89.There were significant differences in the tested materials.All the tested materials were divided into five groups using variableclass average systematic clustering when the Euclidean distance was 10.And they also could be divided into resistant type,middle type and sensitive type based on the characters of SPAD value in different groups.GWAS showed that total 23 single nucleotide polymophisms（SNPs） associated with SPAD value distributed on the wheat chromosomes 1A,2A,2D,3A,3B,4A,4B,4D,5A,5D,6A,6B,6D and 7B,respectively.Four SNPs which were located on chromosome 3B might be related to chlorophyll content.The utilization of iron tolerant wheat germplasms could help to improve the genetic improvement of wheat yield and adaptability,and in-depth study on the correlation SNPs site would be helpful to understand the genetic mechanism of the synthesis and regulation of chlorophyll.