胼胝质合成酶基因（CalS7）调控西瓜对瓜蚜抗性机制研究

瓜蚜（Aphis gossypii Glove）是危害瓜类的重要害虫。韧皮部胼胝质沉积被认为是植物抵御蚜虫等刺吸式昆虫危害的重要机制。胼胝质合成酶基因（CalS）是调控胼胝质合成的关键基因，但CalS基因参与瓜类抗蚜的机制仍不清楚，亟待研究。我们前期研究发现5个西瓜品种受瓜蚜取食后，CalS7基因均显著上调。基于此，我们推测CalS7基因受瓜蚜取食上调表达，介导胼胝质积累而降低瓜蚜取食效率，提高瓜类抗蚜能力。为验证此科学假说，拟以测序西瓜‘97103’-瓜蚜为系统，分析西瓜受瓜蚜取食后胼胝质积累和CalS7基因表达；利用CalS7基因瞬时沉默植株，验证CalS7基因介导胼胝质积累提高西瓜抗蚜能力；利用酵母双杂技术筛选西瓜中与CalS7基因的互作基因，BiFC和Pull-down方法验证，阐释CalS7基因参与西瓜抗蚜的调控机制。为瓜类抗蚜育种提供更多基因，为瓜蚜的绿色防控提供理论支撑。

The melon aphid (Aphis gossypii Glove) is one of the important pests on cucurbit crops. Callose deposition is an vital phloem defense against sap-sucking insects, including aphids. Callose Synthase genes (CalS) are the key genes in regulating callose accumulation. However, it is less known about the underlying mechanisms of CalS genes in regulating the cucurbit crops against aphids infestation. Previous results showed that the relative expression of CalS7 gene was significantly up-regulated in five different watermelon cultivars with melon aphids infestation. Thus，we speculate that the up-regulation of CalS7 gene induced by melon aphids infestation increases the phloem callose deposition, which is disadvantage for the phloem feeding efficiency of melon aphids. Based on this hypothesis, we analyze the content of callose and the expression of leaf CalS7 gene in watermelon plants (97103) with and without melon aphids infestation. And then, the mutation lines of CalS7 gene are used to determine the role of CalS7 gene in regulating phloem callose deposition against melon aphids infestation. Finally, we identify the genes in watermelon plants that interact with CalS7 gene by yeast two-hybrid experiment and confirm the interaction between CalS7 gene and candidate genes by BiFC and Pull-down experiments, which illustrates the underlying molecular mechanisms of CalS7 gene on regulating phloem resistance against melon aphids. Taken together, the current project provides valuable aphid resistance genes for resistance breeding and provides a theoretic basis for green control of melon aphids on cucurbit crops.