Chen Shen, Wang Ling, Que Zhiquen, Pan Ruqian, Pan Qinghua
Laboratory of Plant Resistance and Genetics, College of Resources and Environmental Sciences, South China Agricultural University, Guangzhou 510642, China.
Theor Appl Genet. 2005 Nov;111(8):1563-70. doi: 10.1007/s00122-005-0086-0. Epub 2005 Nov 10.
The famous rice cultivar (cv.), St. No. 1, confers complete resistance to many isolates collected from the South China region. To effectively utilize the resistance, a linkage assay using microsatellite markers (SSR) was performed in the three F2 populations derived from crosses between the donor cv. St. No. 1 and each of the three susceptible cvs. C101PKT, CO39 and AS20-1, which segregated into 3R:1S (resistant/susceptible) ratio, respectively. A total of 180 SSR markers selected from each chromosome equally were screened. The result showed that the two markers RM128 and RM486 located on chromosome 1 were linked to the resistance gene in the respective populations above. This result is not consistent with those previously reported, in which a well-known resistance gene Pif in the St. No. 1 is located on chromosome 11. To confirm this result, additional four SSR markers, which located in the region lanked by RM128 and RM486, were tested. The results showed that markers RM543 and RM319 were closer to, and RM302 and RM212 completely co-segregated with the resistance locus detected in the present study. These results indicated that another resistance gene involved in the St. No. 1, which is located on chromosome 1, and therefore tentatively designated as Pi37(t). To narrow down genomic region of the Pi37(t) locus, eight markers were newly developed in the target region through bioinformatics analysis (BIA) using the publicly available sequences. The linkage analysis with these markers showed that the Pi37(t) locus was mapped to a approximately 0.8 centimorgans (cM) interval flanked by RM543 and FPSM1, where a total of seven markers co-segregated with it. To physically map the locus, the Pi37(t)-linked markers were landed on the reference sequence of cv. Nipponbare through BIA. A contig map corresponding to the locus was constructed based on the reference sequence aligned by the Pi37(t)-linked markers. Consequently, the Pi37(t) locus was defined to 374 kb interval flanking markers RM543 and FPSM1, where only four candidate genes with the resistance gene conserved structure (NBS-LRR) were further identified to a DNA fragment of 60 kb in length by BIA.
著名水稻品种（cv.）圣稻1号对从中国南方地区收集的许多分离株具有完全抗性。为有效利用该抗性，在供体品种圣稻1号与三个感病品种C101PKT、CO39和AS20 - 1杂交产生的三个F2群体中进行了微卫星标记（SSR）连锁分析，这些群体分别以3R:1S（抗性/感病）的比例分离。从每条染色体上均等选取的总共180个SSR标记进行了筛选。结果表明，位于第1染色体上的两个标记RM128和RM486在上述各自群体中与抗性基因连锁。该结果与先前报道不一致，先前报道圣稻1号中一个著名的抗性基因Pif位于第11染色体上。为证实该结果，对位于RM128和RM486两侧区域的另外四个SSR标记进行了检测。结果表明，标记RM543和RM319与抗性位点更接近，而RM302和RM212与本研究中检测到的抗性位点完全共分离。这些结果表明，圣稻1号中存在另一个抗性基因，位于第1染色体上，因此暂命名为Pi37(t)。为缩小Pi37(t)位点的基因组区域，通过利用公开可用序列进行生物信息学分析（BIA），在目标区域新开发了八个标记。与这些标记的连锁分析表明，Pi37(t)位点被定位到RM543和FPSM1两侧约0.8厘摩（cM）的区间，共有七个标记与之共分离。为对该位点进行物理定位，通过BIA将与Pi37(t)连锁的标记定位到日本晴品种的参考序列上。基于与Pi37(t)连锁标记比对的参考序列构建了与该位点对应的重叠群图谱。因此，Pi37(t)位点被定义在标记RM543和FPSM1两侧374 kb的区间内，通过BIA进一步鉴定出该区间内只有四个具有抗性基因保守结构（NBS - LRR）的候选基因，长度为60 kb的DNA片段。
