叶绿体基因infA-rpl36区域在小麦族物种中的序列变异分析

利用小麦叶绿体基因组中infA-rpl36区域的序列设计引物, 对小麦族(Triticeae)的12个二倍体和多倍体的物种进行了PCR扩增和序列测定, 获得了长度为584～603 bp的12条DNA序列。序列分析表明, 供试物种在infA-rpl36基因间隔区的核苷酸变异明显高于基因编码区。基因编码区核苷酸序列同源性高达97%, 表明了目标片段具有高度的保守性。但在5个物种的infA编码区出现了较大的插入、缺失突变, 导致推导的氨基酸序列也发生了很大的变化, 证实了infA基因是叶绿体基因组中最活跃的基因之一, 而rpl36基因的变异较小, 说明不同叶绿体基因的进化速度是不同的。基于测定序列建立的种系树分析发现, 多倍体物种中间偃麦草(Thinopyrum intermedium)具有多种不同的细胞质起源, 与核基因组一样在进化上较为复杂。

Sequence Variation of Chloroplast Gene infA- rpl36 Region Occurred in some Triticeae Species

Based on the sequenced wheat chloroplast genome (cpDNA), a pair of primers in infA-rp136 region was designed and used to amplify DNA from 12 diploid or polyploid Triticeae species. The 12 PCR products were cloned and sequenced. The resulting sequences ranged from 584 to 601bp. DNA sequence analysis revealed that variation was higher in their intergenic regions than in their coding regions. Among these 12 species, the DNA sequence of coding region of infA gene showed homology as high as 97 percent, indicating that the infA gene is highly conserved among species. However, substantial deletions and insertions were found in 5 out of 12 deduced amino acid sequences, confirming that infA is one of the most evolutionally active cpDNA genes. Whereas the low variation was observed in rp136 gene, implying that the different genes has different evolutionary speed. The constructed phylogenetic trees demonstrate that the polyploidy species Thinopyrum intermedium might have different origin of cytoplasm, and their cytoplasm origins are as complex as their nuclear genome origins.