Carpenter Sara C D, Mishra Prashant, Ghoshal Chandrika, Dash Prasanta K, Wang Li, Midha Samriti, Laha Gouri S, Lore Jagjeet S, Kositratana Wichai, Singh Nagendra K, Singh Kuldeep, Patil Prabhu B, Oliva Ricardo, Patarapuwadol Sujin, Bogdanove Adam J, Rai Rhitu
Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States.
Plant Pathogen Interaction, National Research Centre on Plant Biotechnology (ICAR), New Delhi, India.
Front Microbiol. 2018 Nov 13;9:2703. doi: 10.3389/fmicb.2018.02703. eCollection 2018.
The rice bacterial blight pathogen pv. oryzae () injects transcription activator-like effectors (TALEs) that bind and activate host "susceptibility" () genes important for disease. Clade III genes are major S genes for bacterial blight. The resistance genes , which reduces TALE activity generally, and , a allele not recognized by the cognate TALE, have been effectively deployed. However, strains that defeat both resistance genes individually were recently reported in India and Thailand. To gain insight into the mechanism(s), we completely sequenced the genome of one such strain from each country and examined the encoded TALEs. Strikingly, the two strains are clones, sharing nearly identical TALE repertoires, including a TALE known to activate strongly enough to be effective even when diminished by . We next investigated gene induction by the Indian strain. The Indian strain induced no clade III in plants harboring , indicating a pathogen adaptation that relieves dependence on these genes for susceptibility. The findings open a door to mechanistic understanding of the role genes play in susceptibility and illustrate the importance of complete genome sequence-based monitoring of populations in developing varieties with effective disease resistance.
水稻白叶枯病菌（Xanthomonas oryzae pv. oryzae）会注入转录激活样效应因子（TALEs），这些效应因子会结合并激活对病害起重要作用的宿主“感病性”（S）基因。III类S基因是水稻白叶枯病的主要感病基因。抗性基因Xa21（其通常会降低TALE活性）和xa13（一个不被同源TALE识别的S等位基因）已得到有效利用。然而，最近在印度和泰国报道了能分别克服这两个抗性基因的菌株。为深入了解其机制，我们对来自每个国家的一个此类菌株的基因组进行了全测序，并检查了编码的TALEs。令人惊讶的是，这两个菌株是克隆体，共享几乎相同的TALE库，包括一个已知能强烈激活S基因的TALE，即使在被Xa21削弱时也足以有效。接下来，我们研究了印度菌株对S基因的诱导作用。该印度菌株在携带Xa21的植物中未诱导III类S基因，这表明病原菌发生了适应性变化，从而减轻了对这些基因感病性的依赖。这些发现为从机制上理解S基因在感病性中所起的作用打开了一扇门，并说明了在培育具有有效抗病性的品种时，基于全基因组序列监测X. oryzae群体的重要性。
