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作 者 ：韩 淼,汪晓雯,朱小琼,国立耘

期 刊 ：植物病理学报 2016年 46卷 3期 页码：347-356

关键词：致病疫霉；卵菌；RXLR效应因子；Avr3a；Avr4；IPI-O；

Keywords:Phytophthora infestans, oomycete, RXLR effectors, Avr3a, Avr4, IPI-O,

摘 要 ：由致病疫霉(Phytophthora infestans)引起的马铃薯和番茄的晚疫病是一种世界范围内的重要病害。在致病疫霉与寄主的互作过程中,效应因子对于病原物能否成功入侵与定殖起到了关键作用。本研究检测了来自中国马铃薯主产区的37株致病疫霉菌中编码Avr3a, Avr4和IPI-O三种效应因子的基因组成,研究发现来自国内的所有供试菌株中只有1株分离自马铃薯的和2株分离自番茄的致病疫霉含有无毒基因Avr3a(编码Avr3a^KI),其余菌株均含有avr3a(编码Avr3a^EM);所有菌株中都仅含有编码截断蛋白的avr4;从37株国内菌株中共检测到了25种ipiO变异型,其中20种为新变异型,聚类分析的结果表明这些变异型仍属于已报道的三类ipiO,而且大部分ipiO变异型为无毒型,可以被抗性基因Rpi-blb1识别。该研究结果表明avr3a和avr4普遍存在于中国致病疫霉菌株中,推测大部分菌株可以克服R3a和R4抗性基因;而ipiO的无毒变异型仍然普遍存在于国内致病疫霉群体中,可以被马铃薯含有的抗性基因Rpi-blb1识别。

Abstract:Late blight caused by the oomycete Phytophthora infestans is one of the most devastating diseases of potato worldwide. The Avr3a, Avr4 and ipiO are effector encoding genes identified in P. infestans, which can be respectively recognized by the corresponding R genes, R3a, R4 and Rpi-blb1 in potato and lead to the subsequent defense reaction in the host. In this study, we investigated the distribution of Avr3a, Avr4 and ipiO in the population of P. infestans from China. avr4, encoding a truncated protein, was found in all isolates. One isolate from potato and two isolates from tomatoes in Sichuan contained Avr3a (encoding Avr3a^KI) allele, whereas the rest isolates contained avr3a (encoding Avr3a^EM). In total, 25 ipiO variants were detected among these Chinese isolates and 20 of them are new variants. However, all the new ipiO variants belong to the previously classified three ipiO classes and most of the new variants are avirulent. In summary, results of this study suggest that the avr3a and avr4 genes are prevalent in the P. infestans population in China and the resistant gene R3a, R4 of potato can be defeated by most isolates. However, these isolates still contain avirulent ipiO, and they can be recognized by resistant gene Rpi-blb1 in potatoes.

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