稻瘟病抗性基因序列变异的分析与认识是挖掘水稻抗稻瘟病基因资源的基础。对来源于云南省56个县(市)的218份地方稻品种稻瘟病抗性基因Pita第二编码区功能位点区段的609个碱基进行了测序分析。结果表明,所有供试品种在此序列上有18个变异位点,存在46种DNA单倍型和28种蛋白类型,其中DNA单倍型Pita-H1、Pita-H2、 Pita-H6频率较高,三者比例分别为17.89%、29.82%、20.18%,合计67.89%,是云南的优势单倍型,而其他单倍型频率较低,频率0.46%~3.67%。携带Pita抗性基因(编码区第2752位功能位点碱基为G)的品种共61个,占供试材料的27.98%,其中39个品种(占63.93%)与越南抗性品种Tetep序列一致。Pita抗性基因在水稻各亚种和生态型中的分布是不平衡的,籼稻中的频率为35.06%,粳稻中为24.11%,水稻中31.03%,陆稻中21.92%,黏稻中30.77%,糯稻中18.37%。Pita抗性基因在云南省广泛分布,36县(市)检测到了Pita抗性基因,但南部地区频率高于其他地区,且有的县频率较高,呈小集中的特点,海拔2200m以上的7个品种未能检测到Pita抗性基因。

Identification and analysis of the variations of rice blast resistance gene sequence is the basis to dig into the genetic resources of the rice blast resistance. In this paper, 609 bases in the second code functional region of the rice blast resistance gene Pita were analyzed using 218 rice landraces from 56 counties of Yunnan Province. A total of 18 nucleotide variations were found in the sequence and the ORFs of 218 rice accessions were grouped into 46 haplotypes and 28 proteins types. Pita-H1 (17.89%), Pita-H2(29.82%) and Pita-H6(20.18%) were high-frequency types in Yunnan, while other types were at low frequency (0.46%-3.67%). So the advantage haplotypes in Yunnan were Pita-H1, Pita-H2 and Pita-H6 (totally 67.89%). A total of 61 rice landraces carrying the resistance gene Pita, the base functional site 2752 was G with the rate of 27.98%. The sequence of Pita in 39 resistance varieties was identical with the sequence obtained from the Vietnamese resistance variety Tetep. The distribution of resistance gene Pita in rice subspecies or ecotypes was unbalanced. The distribution frequency of indica was 35.06%, japonica 24.11%, rice 31.03%, upland rice 21.92%, no-glutinous rice 30.77%, glutinous rice 18.37%. The distribution of blast resistance gene Pita in Yunnan Province featured wide distribution and small concentration. Pita gene was detected in 36 counties of Yunnan Province. The distribution frequency in southern Yunnan was higher than other area. Moreover, some counties were of high distribution frequency. The resistance gene Pita was not detected in seven rice varieties growing over 2200 m elevation.