A telomeric avirulence gene determines efficacy for the rice blast resistance gene Pi-ta
A telomeric avirulence gene determines efficacy for the rice blast resistance gene Pi-ta
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DOI：
10.1105/tpc.12.11.2019
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发表时间：
2000-11-01
期刊：
影响因子：
11.6
通讯作者：
Valent, B
中科院分区：
文献类型：
--
作者：
Orbach, MJ;Farrall, L;Valent, B
遗传定位表明，稻瘟病毒基因AVR-Pita与稻瘟病菌3号染色体上的一个端粒紧密相连。AVR-Pita以基因对基因的方式对应于抗病(R)基因Pi-ta。对自发性avr-pita（-）突变体的分析表明，该基因位于6.5 kb的BgIII限制性片段端粒中。克隆和DNA测序鉴定了具有金属蛋白酶典型特征的候选基因。该基因完全位于染色体最末端1.5 kb处。当引入毒力强的水稻病原体时，克隆基因对含有Pi-ta的水稻品种具有特异性的无毒作用。频繁的自发性AVR-Pita丢失似乎是其端粒位置的结果。AVR-Pita的多种突变，包括点突变、插入和缺失，允许真菌避免触发由Pi-ta介导的抗性反应。蛋白酶一致序列的点突变取消了AVR-Pita的无毒功能。
Genetic mapping showed that the rice blast avirulence gene AVR-Pita is tightly linked to a telomere on chromosome 3 in the plant pathogenic fungus Magnaporthe grisea. AVR-Pita corresponds in gene-for-gene fashion to the disease resistance (R) gene Pi-ta. Analysis of spontaneous avr-pita(-) mutants indicated that the gene is located in a telomeric 6.5-kb BgIII restriction fragment. Cloning and DNA sequencing led to the identification of a candidate gene with features typical of metalloproteases. This gene is located entirely within the most distal 1.5 kb of the chromosome. When introduced into virulent rice pathogens, the cloned gene specifically confers avirulence toward rice cultivars that contain Pi-ta. Frequent spontaneous loss of AVR-Pita appears to be the result of its telomeric location. Diverse mutations in AVR-Pita, including point mutations, insertions, and deletions, permit the fungus to avoid triggering resistance responses mediated by Pi-ta. A point mutation in the protease consensus sequence abolishes the AVR-Pita avirulence function.