Sequence Analysis of a Hotspot Region in the Chloroplast Genome of Triticum aestivum and Aegilops species

Chinese. 检测了Ae. speltoides和Ae. ovata叶绿体基因组的一个长度热点突变区的核苷酸序列，并与普通小麦、四倍体Ae. crassa 以及Ae. squarrosa的相应序列进行了比较分析。从rbcL基因的终止密码子到cemA基因内的HindIII位点，Ae. speltoides和Ae. ovata的核苷酸序列长度分别为2 808 和 2 810bp。与四倍体Ae. crassa的序列相比，在普通小麦和Ae. speltoides中各有一个791 bp的大片段缺失，在Ae. ovata中存在一个793 bp的大片段缺失。Ae. ovata的缺失片段比普通小麦和Ae. speltoides的长2个碱基，推测Ae. ovata的大片段缺失在进化上是独立发生的。Ae. speltoides的大片段缺失与普通小麦的完全相同，支持Ae. speltoides是普通小麦叶绿体基因组供体的假说。除了大片段缺失外，在这个区域还检测到了7 个插入/缺失和15个碱基替换突变。研究结果表明，这个长度热点突变区的核苷酸序列分析是研究小麦与山羊草叶绿体基因组之间遗传变异关系的一个非常有效的途径。

English. The nucleotide sequences of the hotspot region in the chloroplast genomes were determined in Ae. speltoides and Ae. ovata, and compared with the corresponding sequences in T. aestivum, Ae. crassa 4× and Ae. squarrosa. The total number of nucleotides between a stop codon of rbcL gene and a HindIII site in cemA gene were 2 808 and 2 810 bp in Ae. speltoides and Ae. ovata. Compared with the Ae. crassa 4x, a 791 bp deletion in both of Ae. speltoides and T. aestivum, and a 793 bp deletion in Ae. ovata were identified, respectively. The deleted segment in Ae. ovata is 2 base (TT) longer than that of T. aestivum and Ae. speltoides. This result suggests that the deletion in Ae. ovata occurred independently with that of T. aestivum and Ae. Speltoides. The size and position of a large deletion in Ae. speltoides is identical to that of T. aestivum, this strongly supports the previous conclusion that Ae. speltoides is a donor species of a chloroplast genome to common wheat. In addition to the large segment deletions, a total of 7 insertion/deletion and 15 substitution mutations were observed in the hotspot region. The results indicate that the sequence analysis of the hotspot region is a very powerful tool to investigate genetic variations of chloroplast genome in Triticum and Aegilops.