栽培稻种内核糖体基因的ITS序列比较研究

以普通野生稻(O. rufipogon)为外类群，对栽培稻(O. sativa)籼亚种(O. sativa ssp. indica)和粳亚种(O. sativa ssp. japonica)18个材料的核糖体基因(rDNA)内转录间隔区（internal transcribed spacers, ITS）全序列进行比较分析。供试材料中有籼亚种品种(系)9个，粳亚种品种(系)6个，爪哇稻2个和陆稻1个。结果发现，栽培稻种内总变异位点23个，占总碱基数的5.41%；8个信息位点，占总碱基数的1.82%。籼亚种ITS全序列的长度为425~430 bp，G+C含量为74.25%~75.59%；粳亚种ITS序列总长度为425 bp，G+C含量为74.25%~75.59%。以ITS全序列构建的系统树能将栽培稻区分为籼、粳2个亚种群，爪哇稻与籼稻有较近的亲缘关系，这对研究栽培稻的演化有一定的指导意义。

Comparison of rDNA Internal Transcribed Spacer Sequences in Oryza sativa L.

The cultivated rice has been differentiated and became not only two distinctly discriminative subspecies, i. e. O. sativa ssp. indica and O. sativa ssp. japonica but also many ecotypes of these two subspecies respectively. What is the variation law of the ITS1 and ITS2 sequences in varieties of a certain species with high biological diversity? Can the ITS region be a useful tool to study the phylogenetic relationships among these cultivars? Both of these are worthy of investigation. In this study, a comparative analysis of the rDNA internal transcribed spacers (ITS) entire sequences of 18 cultivars in Oryza sativa L. was carried out with O. rufipogon as outgroup. In the 18 cultivars, there were 9 O. sativa ssp. indica varieties, 6 typical O. sativa ssp. japonica, 2 O. sativa ssp. javanica and 1 upland rice. The result indicated that there were 23 variational loci which were 5.41% of entire bases and 8 informative loci which were 1.82% of entire bases in Oryza sativa. The length range of ITS sequence in O. sativa ssp. indica was from 425 to 430 bp; the percentage of G+C content varied from 74.25% to 75.59%. The length of ITS sequence in O. sativa ssp. japonica was 425 bp and the percentage of G+C content varied from 74.25% to 75.59%. The phylogenetic tree constructed on the basis of the ITS sequences showed that Oryza sativa was discriminated indica and japonica subspecies clearly, meanwhile, Oryza sativa ssp. javanica had closer relationships with O. sativa ssp. indica. The study shows that the sequences analysis of the internal transcribed spacer is a good tool to discriminate between subspecies of Oryza sativa and was significant in research the of Oryza sativa evolution.