Despite the involvement of many members of the chitinase family in the plant immune system, the exact functions of most chitinases remain poorly understood, especially in plant defense responses to phytophagous insects. Here, the gene GhChi6, which encodes a chitinase protein in Gossypium hirsutum, was shown to be induced by cotton aphid feeding and mechanical wounding. Overexpression of GhChi6 in Arabidopsis plants improved their defense response to aphids. The activities of chitinase and PPO in GhChi6 transgenic Arabidopsis plants were higher than those in wild-type plants. Callose deposition in leaves from GhChi6 transgenic Arabidopsis plants was clearly increased compared with wild-type plants. The levels of AtEDS1, AtPAD4, and AtEDS5 in the SA signaling pathway were higher in GhChi6 transgenic Arabidopsis Line4 than those in wild-type plants, while the expression levels of AtLOX2 in the JA signaling pathway and AtEIN2 in the ethylene signaling pathway were lower in GhChi6 transgenic Arabidopsis Line4 than those in wild-type plants. These results collectively showed that the cotton chitinase gene GhChi6 modulated the plant defense response to aphid attack, which may help guide strategies for improving cotton aphid prevention.

中文翻译：

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棉花几丁质酶基因 GhChi6 改善拟南芥对蚜虫攻击的防御反应

尽管几丁质酶家族的许多成员参与了植物免疫系统，但大多数几丁质酶的确切功能仍然知之甚少，尤其是在植物对植食性昆虫的防御反应中。在这里，基因 GhChi6 编码陆地棉中的几丁质酶蛋白，被证明是由棉蚜取食和机械伤害诱导的。GhChi6 在拟南芥植物中的过表达提高了它们对蚜虫的防御反应。GhChi6转基因拟南芥植株中几丁质酶和PPO的活性高于野生型植株。与野生型植物相比，GhChi6 转基因拟南芥植物叶片中的胼胝质沉积明显增加。GhChi6 转基因拟南芥 Line4 中 SA 信号通路中 AtEDS1、AtPAD4 和 AtEDS5 的水平高于野生型植物，而GhChi6转基因拟南芥Line4中JA信号通路中AtLOX2和乙烯信号通路中AtEIN2的表达水平低于野生型植物。这些结果共同表明，棉花几丁质酶基因 GhChi6 调节了植物对蚜虫攻击的防御反应，这可能有助于指导改善棉花蚜虫预防的策略。