Cysteine proteinase inhibitor (cystatin) genes belong to one family of proteinase inhibitors and play an important role in the resistance to insect pests. Cystatin (CYS) genes have been studied in different plant–insect interactions, but there are few reports about the importance of potato cystatin genes. In this study, a cystatin gene named SpCYS was characterized from the wild diploid potato Solanum pinnatisectum Dun, which exhibits high resistance to insect pests. We also investigated the impact of SpCYS in the development of Spodoptera litura when feed from leaves of genetically modified potato. Bioinformatic analysis revealed that SpCYS encoded protein possessed conserved domains of the cystatin family. The SpCYS expression was observed in leaves, stems, roots and tubers with the expression level being almost the same in roots, stems and leaves but greater in tubers. After mechanical damage, SpCYS expression in leaves was induced reaching its peak at 9 h and then decreased to normal levels. Further, we constructed transgenic lines of cultivated potato (cultivar Désirée) expressing SpCYS and performed insect bioassays and feeding preference experiments. Both tests showed that the over-expression of SpCYS lowered the weight increase rate of both Spodoptera litura larvae and pupa. S. litura larvae preferred to feed on the leaves of non-transformed controls rather than the transgenic lines. Taken together, our data suggest that SpCYS is a significant asset for the defense mechanism of potato against S. litura.

中文翻译：

---

SpCYS是野生马铃薯（Solanum pinnatisectum）的半胱氨酸蛋白酶抑制剂基因，与斜纹夜蛾抗药性有关。

半胱氨酸蛋白酶抑制剂（胱抑素）基因属于蛋白酶抑制剂的一个家族，在抗虫害中起重要作用。胱抑素（CYS）基因已经在不同的植物-昆虫相互作用中进行了研究，但是关于马铃薯胱抑素基因重要性的报道很少。在这项研究中，从野生二倍体马铃薯Solanum pinnatisectum Dun鉴定出一个名为SpCYS的胱抑素基因，该马铃薯对害虫具有很高的抗性。当我们从转基因马铃薯的叶片中采食时，我们还研究了SpCYS对斜纹夜蛾发育的影响。生物信息学分析表明，SpCYS编码的蛋白具有胱抑素家族的保守结构域。所述SpCYS在叶中观察到的表达，茎，根和块茎的表达水平是几乎在根中是相同的，茎，叶，但大于在块茎。机械损伤后，诱导叶片中的SpCYS表达在9 h达到峰值，然后降至正常水平。此外，我们构建了表达SpCYS的栽培马铃薯（栽培品种Désirée）的转基因品系，并进行了昆虫生物测定和饲喂偏好实验。两项测试均显示，SpCYS的过表达降低了斜纹夜蛾幼虫和的体重增加率。荔枝幼虫更喜欢以未转化对照的叶子为食，而不是以转基因品系为食。综上所述，我们的数据表明，SpCYS是马铃薯抗斜纹夜蛾防御机制的重要资产。