Cooperative effect of two amino acid mutations in the coat protein of Pepper mild mottle virus overcomes L3-mediated resistance in Capsicum plants
Cooperative effect of two amino acid mutations in the coat protein of Pepper mild mottle virus overcomes L3-mediated resistance in Capsicum plants
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DOI：
10.1007/s11262-006-0049-9
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发表时间：
2007-04-01
期刊：
影响因子：
1.6
通讯作者：
Suzuki, Kazumi
中科院分区：
文献类型：
--
作者：
Hamada, Hiroyuki;Tomita, Reiko;Suzuki, Kazumi
研究发现，辣椒轻度斑驳病毒（PMMoV）的L-3抗性田间分离物PMMoV- is与PMMoV- j相比，其外壳蛋白（CP）发生了2个氨基酸变化，即13号位置的亮氨酸变为苯丙氨酸（L13F）和66号位置的甘氨酸变为缬氨酸（G66V），从而诱导了L-3抗性的产生。在计算分子模型中，突变位于PMMoV颗粒外表面对应的CP结构域。对含有这两种氨基酸变化中的一种或两种的PMMoV CP突变体的分析表明，这两种变化都是有效克服l -3介导的系统性坏死诱导抗性所必需的。虽然含有L13F或G66V的CP突变体都不能有效地克服l -3介导的抗性，但这些氨基酸的变化对PMMoV CP的激发子活性有不同的影响。L13F引起激发子活性的轻微降低，导致病毒对坏死局部病变的限制明显大于野生型PMMoV诱导的，而G66V使野生型PMMoV能够克服l -3介导的抗性。尽管效率低于两种变化的PMMoV。这些结果表明，L13F和G66V突变对CP激发子活性的协同作用是克服l -3介导的抗性的原因。
We found that an L-3 resistance-breaking field isolate of Pepper mild mottle virus (PMMoV), designated PMMoV-Is, had two amino acid changes in its coat protein (CP), namely leucine to phenylalanine at position 13 (L13F) and glycine to valine at position 66 (G66V), as compared with PMMoV-J, which induces a resistance response in L-3-harboring Capsicum plants. The mutations were located to a CP domain corresponding to the outer surface of PMMoV particles in computational molecular modeling. Analyses of PMMoV CP mutants containing either or both of these amino acid changes revealed that both changes were required to efficiently overcome L-3-mediated resistance with systemic necrosis induction. Although CP mutants containing either L13F or G66V could not efficiently overcome L-3-mediated resistance, these amino acid changes had different effects on the elicitor activity of PMMoV CP. L13F caused a slight reduction in the elicitor activity, resulting in virus restriction to necrotic local lesions that were apparently larger than those induced by wild-type PMMoV, while G66V rendered wild-type PMMoV the ability to overcome L-3-mediated resistance, albeit with a lower efficiency than PMMoV with both changes. These results suggest that a cooperative effect of the L13F and G66V mutations on the elicitor activity of CP is responsible for overcoming the L-3-mediated resistance.