草地贪夜蛾与斜纹夜蛾嗅觉味觉相关基因的比较分析

Comparison of olfactory and gustatory genes between Spodoptera frugiperda and Spodoptera litura

草地贪夜蛾 Spodoptera frugiperda,近期侵入中国并迅速扩张。与其近缘物种斜纹夜蛾Spodoptera litura 不同,草地贪夜蛾主要偏好玉米、水稻、小麦等禾本科农作物,暴食危害重。此外两种害虫在交配、产卵频率等繁殖特征上也存在差异。这些差异可能与嗅觉、味觉相关蛋白的分歧密切相关。本研究对两种夜蛾科害虫的嗅觉、味觉相关基因进行了系统的鉴定及系统发育分析,并对部分嗅觉结合蛋白进行了选择信号与氨基酸差异位点分析。分别在草地贪夜蛾中鉴定到261个嗅觉相关基因,数目明显大于斜纹夜蛾(179个);鉴定到233个味觉相关基因,数目略大于斜纹夜蛾(217个)。嗅觉相关基因中气味结合蛋白(OBP)基因数目差异最为明显。系统发育分析显示该基因存在夜蛾科特异的分支,且该分支中草地贪夜蛾中基因数目远高于斜纹夜蛾;发现位于I类触角结合蛋白(ABPI)分支的一类OBP成员在草地贪夜蛾中拷贝数增加,其中两个基因拷贝受到正选择,且在草地贪夜蛾中特有的氨基酸替换还可能影响蛋白质功能。本研究为草地贪夜蛾食性特征的遗传机制解析提供线索,为草地贪夜蛾的生物防治提供参考依据和基因素材。

Recently, a gluttonous pest, the fall armyworm Spodoptera frugiperda invaded in China, ravaging crops and threatening the vast supply of maize.Compared with its relative, the tobacco cutworm Spodoptera litura , S.frugiperda mainly prefers graminaceous plants such as corn, rice and wheat.In addition, there are differences in the reproduction characteristics of the two pests, such as mating and spawning frequency.Differences in olfactory and taste related genes between the two relatives are possibly one important cause.In this study, we collected and identified olfactory and gustatory genes of the two relatives, constructed phylogenetic trees of these genes, test the selection signals and analyzed the divergent amino acid site in some odorant binding proteins.We totally identified 261 olfactory genes in S.frugiperda , which are obviously more than those in S.litura (179);we identified 233 gustatory genes in S.frugiperda , slightly more than those in S.litura (217).Among the olfactory genes, the number of the olfactory binding protein (OBP) genes were was most remarkably different between the two relatives.Phylogenetic analysis showed that there was a Noctuidae specific clade of the OBPs, in which the number of genes in S.frugiperda was much higher than that in S.litura .OBPs in another group belonging to antennal binding protein I (ABPI clade) also showed increased gene numbers in S.frugiperda .Two gene copies in this clade showed positive selection signal in S.frugiperda .Furthermore, S.frugiperda specific replacements in two amino acids were predicted to affect the protein function.This study provides not only clues for the understanding of the genetic mechanism underlying feeding and mating characteristics of S.frugiperda and but also reference and genetic material for its biological control.