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

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(448bpGA)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,P0.01),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=18.48t0.01=2.62,P0.01);(4)ahFAD2A等位基因的存在与种子油酸含量密切相关。

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

Oleic acid content of cultivated peanut (Arachis hypogaea L.) seeds is controlled by the activity of oleoyl-PC desaturase, encoded by two homologous genes (ahFAD2A and ahFAD2B), high oleic acid content results from the mutation of ahFAD2A and ahFAD2B, simultaneously. Two alleles of the ahFAD2A (wild type ahFAD2A-wt and mutation type ahFAD2A-m) exist in the normal oleic accessions, whereas only the ahFAD2A-m allele exists in the high oleic accessions. The ahFAD2A-m is a spontaneous mutation type of ahFAD2A-wt (G-to-A at site 448 bp resulting in a D to N at 150 amino acid position), which results in a dysfunctional desaturase. A specific PCR primer pair for the ahFAD2A amplification was developed in this study. According to the sequencing result of PCR production of the mutant and wild-type ahFAD2A alleles, mutant allele (ahFAD2A-m) accounted for 53.1% of the accessions in the mini-core collection from China, which was frequently found in subspecies hypogaea accessions but absent from subspecies fastigiata accessions; the highly positive correlation between the ahFAD2A-m and the higher oleic acid content was observed. A new SNP was found at the 417 bp (T/C) in the open reading frame (ORF), which did not result in the amino acid substitution, and was found no correlation between the SNP of 417 bp and the oleic content. These results will be helpful for the breeders to select the parent material in the peanut high oleic acid breeding program.