ahFAD2A等位基因在中国花生小核心种质中的分布及其与种子油酸含量的相关性分析

Frequencies of ahFAD2A Alleles in Chinese Peanut Mini Core Collection and Its Correlation with Oleic Acid Content

在中国小核心花生种质中发掘出油酰PC脱氢酶的2个等位基因(ahFAD2A-wt和ahFAD2A-m)。研究结果表明:(1)突变型等位基因(ahFAD2A-m)与野生型等位基因(ahFAD2A-wt)在编码区442bp的SNP(448bpG>A)可导致编码氨基酸的替换(D150N);(2)突变型基因ahFAD2A-m在中国花生小核心种质中广泛存在,出现的频率为53.1%,野生型基因ahFAD2A-wt出现的频率为46.9%;(3)突变型基因ahFAD2A-m在密枝亚种(普通型和龙生型变种)中出现的频率(82.8%)显著高于其在疏枝亚种(珍珠豆型和多粒型变种)材料中出现的频率(15.4%),卡方测验结果表明,核心种质的油酸含量与其携带的等位基因类型密切相关(χ2=98.71,χ20.01,3=11.34,P<0.01),携带突变型基因(ahFAD2A-m)材料的油酸平均值显著高于野生型基因的材料(t=18.48>t0.01=2.62,P<0.01);(4)ahFAD2A等位基因的存在与种子油酸含量密切相关。

Oleic acid content of cultivated peanut（Arachis hypogaea L.） seeds is controlled by the activity of oleoyl-PC desaturase that is encoded by two homologous genes（ahFAD2A and ahFAD2B）.High content of oleic acid results from the both mutation at ahFAD2A and ahFAD2B,loci.Two alleles of ahFAD2A,ahFAD2A-wt（wild type） and ahFAD2A-m（mutation type） exist in normal oleic accessions,whereas the ahFAD2A-m allele only exists in the high oleic accessions.Allele ahFAD2A-m is a spontaneous of ahFAD2A-wt（G-to-A at site 448 bp leading to the substitution from D to N at 150 amino acid position）,which results in a dysfunctional desaturase.A pair of specific PCR primers for the ahFAD2A was developed for PCR amplification.According to the sequencing result of PCR productions of ahFAD2A-wt and ahFAD2A-m,accounted for 53.1% of the total accessions from the Chinese mini-core collection carried ahFAD2A-m,and this allele was frequently found in A.hypogaea subsp.hypogaea,but often absent from A.hypogaea subsp.fastigiat.A highly positive correlation was observed between the presence of ahFAD2A-m and the higher content of oleic acid in peanut seeds.A new SNP was found（T/C） at site 417 bp in the open reading frame resulted in no changes of amino acid alignment.This SNP had no correlation with oleic content.These results are helpful for selecting peanut parents with high oleic acid in breeding programs.