Occurrence and diversity of Tomato spotted wilt virus isolates breaking the Tsw resistance gene of Capsicum chinense in Yunnan, southwest China
Occurrence and diversity of Tomato spotted wilt virus isolates breaking the Tsw resistance gene of Capsicum chinense in Yunnan, southwest China
复制标题
云南省辣椒Tsw抗性基因番茄斑萎病毒分离株的发生及多样性
DOI：
10.1111/ppa.12645
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发表时间：
2017-08-01
期刊：
影响因子：
2.7
通讯作者：
Tao, X.
中科院分区：
文献类型：
--
作者：
Jiang, L.;Huang, Y.;Tao, X.
具有Tsw位点的抗性辣椒（Capsicum spp）被广泛使用，引发了番茄斑点枯萎病毒（TSWV）抗性突破（RB）分离株在世界范围内的迅速出现。但目前国内尚未见RB分离株的报道。近年来，由tswv引起的疾病在云南迅速增加。没有关于云南TSWV分离株多样性的资料。在这项研究中，我们报告了在云南收集的分离株中发生的自然TSWV RB变异。我们最初于2012年在云南从芦笋生菜中采集到一株TSWV分离株（TSWV - le）。令人惊讶的是，这个TSWV分离株在携带TSWV抗性基因的辣椒上诱导了全身性坏死。随后，我们于2015年收集了新的TSWV分离株，发现番茄分离株（TSWV - yn18）和烟草分离株（TSWV - yn53）也克服了TSWV介导的抗性。TSWV-YN18引起全身环斑，而YN53引起全身褪绿斑驳。TSWV NSs蛋白的变异是与TSWV耐药分离株相关的关键决定因素。我们发现TSWV-LE NSs保留了超敏反应（hypersensitive response， HR）诱导，而TSWV-YN18和-YN53 NSs不能诱导HR。然而，所有三个RB分离株的NSs都抑制RNA沉默。NSs序列分析显示，云南RB分离株不存在与以往报道的RB分离株相同的氨基酸突变位点。然而，LE-NSs上的两个氨基酸（F74和K272）使其与YN18和YN53 RB分离株有所区别。不同RB菌株的出现和tsw介导的抗性控制失败对西南地区辣椒作物构成严重威胁。
Widely-used resistant peppers (Capsicum spp.) bearing the Tsw locus triggered the rapid emergence of resistance breaking (RB) isolates of Tomato spotted wilt virus (TSWV) around the world. However, no RB isolates have been reported so far in China. TSWV-induced diseases rapidly increased in Yunnan, Southwest China, in recent years. No information is available about the diversity of TSWV isolates in Yunnan. In this study, we report the occurrence of natural TSWV RB variants among isolates collected in Yunnan. We initially collected a TSWV isolate from asparagus lettuce (TSWV–LE) in Yunnan in 2012. Surprisingly, this isolate of TSWV induced systemic necrosis on pepper carrying Tsw-resistance gene. We then collected novel TSWV isolates in 2015 and found that a tomato-isolate (TSWV–YN18) and a tobacco-isolate (TSWV–YN53) also overcome the Tsw-mediated resistance. TSWV–YN18 induced systemic ringspots, whereas YN53 caused systemic chlorotic mottle. Variations in the TSWV NSs protein are the key determinants associated with Tsw resistance-breaking isolates. We found that TSWV-LE NSs retains the hypersensitive response (HR) induction, whereas TSWV–YN18 and –YN53 NSs are unable to induce HR. However, the NSs of all three RB isolates suppress RNA silencing. Sequence analysis of NSs revealed that RB isolates of Yunnan have no amino acid mutation sites common to other previously reported RB isolates. However two amino acids (F74 and K272) on LE-NSs make it distinct from YN18 and YN53 RB isolates. The occurrence of different RB isolates and the failure of Tsw-mediated resistance control pose serious threats to domestic pepper crops in Southwest China.
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