Souza Thais P, Dias Renata O, Castelhano Elaine C, Brandão Marcelo M, Moura Daniel S, Silva-Filho Marcio C
Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Av. Pádua Dias, 11, 13400-918 Piracicaba, SP, Brazil.
Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Av. Cândido Rondon, 400, 13083-875 Campinas, SP, Brazil.
Comp Biochem Physiol B Biochem Mol Biol. 2016 Jun-Jul;196-197:67-73. doi: 10.1016/j.cbpb.2016.02.007. Epub 2016 Mar 2.
Peptidase inhibitors (PIs) are essential proteins involved in plant resistance to herbivorous insects, yet many insect species are able to escape the negative effects of these molecules. We compared the effects of acute and chronic ingestion of soybean peptidase inhibitors (SPIs) on Spodoptera frugiperda and Diatraea saccharalis, two Lepidoptera species with different sensitivities to SPI ingestion. We analyzed the trypsin and chymotrypsin gene expression profiles in both species. Acute exposure of S. frugiperda to the inhibitors activated seven genes (SfChy5, SfChy9, SfChy19, SfChy22, SfTry6, SfTry8, and SfTry10), whereas chronic exposure activated 16 genes (SfChy2, SfChy4, SfChy5, SfChy8, SfChy9, SfChy11, SfChy12, SfChy15, SfChy17, SfChy21, SfChy22, SfTry6, SfTry8, SfTry9, SfTry10, and SfTry12). By contrast, the challenge of D. saccharalis with SPIs did not differentially induce the expression of trypsin- or chymotrypsin-encoding genes, with the exception of DsChy7. Bayesian phylogenetic analysis of S. frugiperda trypsin protein sequences revealed two gene clades: one composed of genes responsive to the SPIs and a second composed of the unresponsive genes. D. saccharalis trypsin proteins were clustered nearest to the S. frugiperda unresponsive genes. Overall, our findings support a hypothesized mechanism of resistance of Noctuidae moths to SPIs, involving gene number expansion of trypsin and chymotrypsin families and regulation of gene expression, which could also explain the variable susceptibility between S. frugiperda and D. saccharalis to these plant inhibitors.
肽酶抑制剂（PIs）是参与植物对食草昆虫抗性的重要蛋白质，但许多昆虫物种能够逃避这些分子的负面影响。我们比较了急性和慢性摄入大豆肽酶抑制剂（SPIs）对草地贪夜蛾和甘蔗二点螟这两种对SPI摄入敏感性不同的鳞翅目物种的影响。我们分析了这两个物种中胰蛋白酶和胰凝乳蛋白酶的基因表达谱。草地贪夜蛾急性暴露于抑制剂激活了7个基因（SfChy5、SfChy9、SfChy19、SfChy22、SfTry6、SfTry8和SfTry10），而慢性暴露激活了16个基因（SfChy2、SfChy4、SfChy5、SfChy8、SfChy9、SfChy11、SfChy12、SfChy15、SfChy17、SfChy21、SfChy22、SfTry6、SfTry8、SfTry9、SfTry10和SfTry12）。相比之下，甘蔗二点螟受到SPIs刺激后，除了DsChy7外，并未差异诱导胰蛋白酶或胰凝乳蛋白酶编码基因的表达。对草地贪夜蛾胰蛋白酶蛋白序列的贝叶斯系统发育分析揭示了两个基因分支：一个由对SPIs有反应的基因组成，另一个由无反应的基因组成。甘蔗二点螟的胰蛋白酶蛋白最接近草地贪夜蛾无反应的基因聚类。总体而言，我们的研究结果支持夜蛾科蛾类对SPIs抗性的一种假设机制，即涉及胰蛋白酶和胰凝乳蛋白酶家族的基因数量扩展以及基因表达调控，这也可以解释草地贪夜蛾和甘蔗二点螟对这些植物抑制剂的易感性差异。
