Abscisic acid (ABA) is a vital hormone that regulates stomatal closure and responds to stress conditions in plants. Therefore, ABA signal pathway involves numerous physiological processes in plants, such as seed dormancy, germination, development and ripening. Among the families of ABA receptor genes, ABA-insensitive (ABI) is a major transcription factor that regulates ABA signal pathway. To date, little information is known about the ABI gene of buckwheat. To characterize ABI gene sequence polymorphism and genetic relationship of genus Fagopyrum, the budlets of 30 germplasm resources from seven wild species including F. esculentum, F. tataricum, F. zuogongense, F. pilus, F. megaspartanium, F. cymosum and F. urophyllum were collected for DNA extraction. The ABI UniGene sequence of buckwheat was isolated from the previously performed transcriptome sequencing data (accession number:SRS1350375). Specific primers of ABI gene were designed based on the high conservative sequence for polymerase chain reaction (PCR) amplification, and the amplified fragments from 30 germplasm resources were processed for gene sequencing. Then the gene sequence analysis was performed on nucleotide BLAST of NCBI database (http://blast.ncbi.nlm.nih.gov/Blast.cgi), and the genetic variance was analyzed by DNAsp5, and the analysis of ClustalW multiple sequence alignment, genetic distance and hierarchy were clustered by MEGA 5.05. The results showed that 20.28%of polymorphic sites were found in ABI gene fragments among 30 germplasm resources of the seven wild species of genus Fagopyrum, whereas only 1.86%of polymorphic sites were found among 14 germplasm resources of F. tataricum and 1.81%of polymorphic sites were found among five germplasm resources of F. esculentum, indicating that ABI gene sequence is highly conserved in the intraspecies of genus Fagopyrum. Genetic distance analysis showed that both the values of interspecific genetic distance and interspecific net genetic distance between F. zuogongense and F. pilus were the largest, whereas those between F. cymosum and F. urophyllum were the least based on the ABI gene sequence analysis. Hierarchical cluster analysis indicated that the phylogenetic relationship of F. tataricum was close to F. megaspartanium, F. cymosum and F. urophyllum, then further grouped with F. pilus, while the F. esculentum was close to F. zuogongense based on the ABI gene sequence analysis. The F. tataricum and F. zuogongense collected from different regions were respectively clustered, suggesting that the mutation of ABI gene might be influenced by the growth environment during plant evolution. In conclusion, ABI gene sequence is highly conserved in the intraspecies of genus Fagopyrum;nevertheless, different growth environments caused distinctive mutations of ABI gene. Based on the gene sequence analysis, a close relationship was found between F. esculentum and F. zuogongense. In addition, close relationships were also found among F. tataricum, F. megaspartanium, F. cymosum and F. urophyllum. The above results provide a theoretical basis for ABI gene research and evolutionary relationship of genus Fagopyrum, but the exact evolution among different species of buckwheat still needs further research.%为了研究荞麦属不同种间植物脱落酸不敏感基因(ABA-insensitive,ABI)序列变异差异与亲缘关系,试验选用7个荞麦野生种,包括野甜荞、野苦荞、左贡野荞、毛野荞、大野荞、金荞麦、硬枝万年荞共30份种质材料,提取苗期幼嫩叶片的DNA,通过聚合酶链式反应(polymerase chain reaction,PCR)扩增获得荞麦ABI基因,并对扩增片段进行基因测序与序列分析.结果发现,7个野生种共30份种质间ABI基因片段的多态位点数占20.28%,其中,14份野苦荞间ABI基因片段多态位点数占1.86%,5份野甜荞间多态位点数占1.81%,说明荞麦属植物种内ABI基因序列高度保守.对扩增序列进行遗传距离分析发现,左贡野荞与毛野荞种间遗传距离最大,硬枝万年荞与金荞麦种间遗传距离最小.聚类分析结果显示:野苦荞与大野荞、金荞麦和硬枝万年荞亲缘关系较近,与毛野荞亲缘关系次之;左贡野荞与野甜荞亲缘关系近;不同地区野苦荞和左贡野荞分别被单独聚为一类,说明生长环境对荞麦ABI基因序列变异具有影响.
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