Molecular mapping of the Pi2/9 allelic gene Pi2-2 conferring broad-spectrum resistance to Magnaporthe oryzae in the rice cultivar Jefferson

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Nan Jiang, Zhiqiang Li, Jun Wu, Yue Wang, Liqun Wu, Suhua Wang, Dan Wang, Ting Wen, Yi Liang, Pingyong Sun, Jinling Liu, Liangying Dai, Zhilong Wang, Chao Wang, Meizhong Luo, Xionglun Liu, Guo-Liang Wang
Rice, 2012, 5 : 29  DOI: 10.1186/1939-8433-5-29     追溯原文......本站官方QQ群:62473826
Rice blast; Resistance gene; Mapping; BAC clones; Pi2/9 locus

Background: Utilization of broad-spectrum resistance (R) genes is an effective and economical strategy to control the fungal pathogen Magnaporthe oryzae, the causal agent of the rice blast disease. Among the cloned blast resistance genes, Pi9, Pi2 and Piz-t confer broad-spectrum resistance to diverse M. oryzae isolates and were isolated from the Pi2/9 locus on chromosome 6. Identification and isolation of additional R genes with different resistance spectra from this locus will provide novel genetic resources for better control of this important rice disease.
Results: In this study, we identified a dominant R gene, Pi2-2, at the Pi2/9 locus from Jefferson, an elite U.S. rice cultivar, through genetic and physical mapping. Inoculation tests showed that Jefferson has different resistant specificities to M. oryzae isolates compared rice lines with the Pi9, Pi2 and Piz-t genes. Fine mapping delimited Pi2-2 to a 270-kb interval between the markers AP5659-3 and RM19817, and this interval contains three nucleotide-binding site-leucine-rich repeat (NBS-LRR) genes in the Nipponbare genome. Five bacterial artificial chromosome (BAC) clones spanning the region were identified, and a BAC contig covering the Pi2-2 locus was constructed.
Conclusions: We identified a new allelic gene at the Pi2/9 locus and fine-mapped the gene within a 270-kb region. Our results provide essential information for the isolation of the Pi2-2 gene and tightly linked DNA markers for rice blast resistance breeding.

水稻品种Jefferson广谱抗稻瘟病基因Pi2/9等位基因Pi2-2的定位

背景:利用广谱抗性基因(R)是控制水稻真菌性病害稻瘟病的一种经济有效的策略。作为已克隆的抗稻瘟病基因,Pi9Pi2Piz-t都具有广谱抗性,Pi2/9区域位于6号染色体上。从这个位点识别出含不同抗谱的R基因将提供新的遗传资源,从而更好地控制这一重要的水稻病害。
结果:本研究中我们通过遗传分析和图位克隆从水稻品种Jefferson(美国原种)中鉴定出了一个显性R基因Pi2-2,位于Pi2/9区域,接种试验表明,Jefferson与带有Pi9Pi2Piz-t的水稻品系相比,具有不同的抗病特异性。Pi2-2精细定位于第6染色体上,标记RM19817与AP5659-3之间大约270kb的区域内,根据日本晴基因组这个区段含有3个核苷酸结合位点 - 富含亮氨酸的重复序列(NBS-LRR)。5个覆盖该区段的BAC克隆已鉴定,其中一个BAC重叠覆盖了Pi2-2位点。
结论:我们在Pi2/9区域确定了一个新的等位基因并精细定位到270 kb的区域内。研究结果为Pi2-2基因的分离和对稻瘟病抗性育种紧密连锁的DNA标记提供了重要信息。


基因列表
  稻瘟病抗性基因 Pi9; Pi2/Piz-5; Pi50; Piz; Pi
品种列表
  Jefferson