Effective and durable disease resistance for bacterial blight (BB) of rice is a continuous challenge due to the evolution and adaptation of the pathogen, Xanthomonas oryzae pv. oryzae (Xoo), on cultivated rice varieties. Fundamental to this pathogens’ virulence is transcription activator‐like (TAL) effectors that activate transcription of host genes and contribute differently to pathogen virulence, fitness or both. Host plant resistance is predicted to be more durable if directed at strategic virulence factors that impact both pathogen virulence and fitness. We characterized Tal7b, a minor‐effect virulence factor that contributes incrementally to pathogen virulence in rice, is a fitness factor to the pathogen and is widely present in geographically diverse strains of Xoo. To identify sources of resistance to this conserved effector, we used a highly virulent strain carrying a plasmid borne copy of Tal7b to screen an indica multi‐parent advanced generation inter‐cross (MAGIC) population. Of 18 QTL revealed by genome‐wide association studies and interval mapping analysis, six were specific to Tal7b (qBB‐tal7b). Overall, 150 predicted Tal7b gene targets overlapped with qBB‐tal7b QTL. Of these, 21 showed polymorphisms in the predicted effector binding element (EBE) site and 23 lost the EBE sequence altogether. Inoculation and bioinformatics studies suggest that the Tal7b target in one of the Tal7b‐specific QTL, qBB‐tal7b‐8, is a disease susceptibility gene and that the resistance mechanism for this locus may be through loss of susceptibility. Our work demonstrates that minor‐effect virulence factors significantly contribute to disease and provide a potential new approach to identify effective disease resistance.

中文翻译：

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通过用来自 Xanthomonas oryzae pv. 稻米。

由于病原体米黄单胞菌pv的进化和适应，对水稻白叶枯病 (BB) 的有效和持久的抗病性是一个持续的挑战。稻瘟病菌（Xoo)，关于栽培水稻品种。这种病原体毒力的基础是转录激活因子样 (TAL) 效应子，它激活宿主基因的转录并对病原体的毒力、适应性或两者都有不同的贡献。如果针对影响病原体毒力和适应性的战略毒力因素，预计宿主植物的抗性将更加持久。我们对 Tal7b 进行了表征，这是一种影响水稻病原体毒力的微效毒力因子，是病原体的适应性因子，广泛存在于地理上不同的Xoo菌株中. 为了确定对这种保守效应子的抗性来源，我们使用了一种携带质粒携带的 Tal7b 拷贝的高毒性菌株来筛选籼稻多亲先进代杂交 (MAGIC) 种群。在全基因组关联研究和区间作图分析揭示的 18 个 QTL 中，有 6 个是 Tal7b (qBB- tal7b ) 特异性的。总体而言，150 个预测的 Tal7b 基因靶标与 qBB -tal7b QTL 重叠。其中，21 个在预测的效应结合元件 (EBE) 位点显示多态性，23 个完全丢失了 EBE 序列。接种和生物信息学研究表明，Tal7b 靶向 Tal7b 特异性 QTL 之一，qBB- tal7b‐8，是一种疾病易感基因，并且该位点的抗性机制可能是通过易感性的丧失。我们的工作表明，微效毒力因子对疾病有显着影响，并为确定有效的抗病性提供了一种潜在的新方法。