花生ahFAD2A等位基因表达变异与种子油酸积累关系

花生ahFAD2A是控制种子油酸、亚油酸含量和油亚比的关键基因。利用ahFAD2A基因特异引物检测远杂9102, 豫花9416等52个花生品种的ahFAD2A基因等位变异, 并比较其中13个品种的ahFAD2A基因序列。结果表明, 花生ahFAD2A基因存在G-A两种单核苷酸等位变异(野生型ahFAD2A-wt和突变体ahFAD2A-m), DNA序列比对结果证实, 豫花9416等10个品种(突变体)与远杂9102、延津花籽和开农白2号(野生型)相比, 在ahFAD2A基因的448 bp处存在核苷酸G-A突变。应用real-time PCR检测ahFAD2A等位基因在种子不同发育时期的表达动态显示突变体豫花9416等位基因(ahFAD2A-m)在种子发育中期表达量稍高, 种子发育后期表达量下降速度较野生型远杂9102(ahFAD2A-wt)更快。进一步测定豫花9416和远杂9102在种子不同发育时期的油酸、亚油酸积累和油亚比动态, 发现两品种间存在明显差异, 豫花9416在籽粒发育前期油酸相对含量已超过亚油酸, 油亚比大于１并逐渐增加, 而远杂9102到籽粒发育中后期油酸相对含量才高于亚油酸, 油亚比逐渐接近于１左右。

Allelic Expression Variation of ahFAD2A and Its Relationship with Oleic Acid Accumulation in Peanut

ahFAD2A is a key regulator controlling oleic acid content in peanut. Using ahFAD2A allelic specific primers, the allelic variations of ahFAD2A were tested in 52 peanut varieties and the DNA sequences of 13 typical varieties, including Yuanza 9102, Yuhua 9416, wt08-0932, and wt08-0934, were compared. PCR results revealed that the presence of two alleles of ahFAD2A (referred as to wild type ahFAD2A-wt and mutant ahFAD2A-m respectively) in peanut germplasm, and the G/A single nucleotide polymorphism (SNP) at 448 bp site of ahFAD2A was further confirmed by sequences comparison of 13 peanut varieties. Allelic expression variations of ahFAD2A alleles in peanut seeds were detected by real-time PCR at different developmental stages. The results indicated that the expression level of mutant allele (ahFAD2A-m) from Yuhua 9416 was slightly higher than that of the wild type allele (ahFAD2A-wt) from Yuanza 9102 during the early to middle developmental stages (17–38 days). However, a rapid decrease in expression level was observed for the mutant allele as compared with its wild type at the late developmental stage (after 45 days). Further determination revealed that the ahFAD2A-m genotype showed higher oleic acid content than linoleic acid content with high O/L ratio (>1.0) starting at early seed developmental stages in Yuhua 9416 while the ahFAD2A-wt genotype remained lower oleic acid content than linoleic acid content with steady O/L ratio (<1.0) until seed maturity stage in Yuanza 9102. This relationship between oleic acid accumulation and ahFAD2A allelic expression variation in peanut provide the fundamentalinformation for genetic regulation and improvement of seed oleic acids content.