Plant defensins are small, cationic, cysteine-rich peptides with well conserved four disulphide bridges between an α-helix and three anti-parallel β-strands, produced by plants as a first line of innate immunity against the invading fungal pathogens. Some of the plant defensins exhibit strong antibacterial and anti-insect activities in vitro as well as in vivo. TvD1, a defensin from Tephrosia villosa was characterized in our previous studies with demonstrated inhibitory effect against many plant pathogenic fungi and some insects. To further enhance its activity, α-TvD1, a peptide variant of TvD1, was generated through site directed mutagenesis. It showed enhanced antifungal and Tenebrio molitor α-amylase inhibitory activity under in vitro condition. In the present study, we compared the antifungal and anti-insect activities of α-TvD1 with the native TvD1 in transgenic tobacco plants. α-TvD1 transgenic plants showed enhanced tolerance against the oomycetes pathogen Phytophthora parasitica var. nicotianae and the fungal pathogens Alternaria alternata and Rhizoctonia solani. Also, it showed enhanced anti-insect activity against the 1st and 2nd instar larvae of the generalist herbivore, Spodoptera litura. These results demonstrated that α-TvD1 appears to be a potent antimicrobial gene that can be used for generating superior transgenic crops with enhanced resistance against many phytopathogens and insect pests.

中文翻译：

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一种体外产生的长毛毛茛防御素变体（α-TvD1）增强转基因烟草的生物胁迫耐受性

植物防御素是小的、阳离子、富含半胱氨酸的肽，在 α-螺旋和三个反平行的 β-链之间具有四个高度保守的二硫桥，由植物产生，作为抵抗入侵真菌病原体的第一道先天免疫线。一些植物防御素在体外和体内都表现出很强的抗菌和抗虫活性。TvD1 是一种来自长毛毛茛的防御素，在我们之前的研究中对许多植物病原真菌和一些昆虫具有抑制作用。为了进一步增强其活性，通过定点诱变产生了 TvD1 的肽变体 α-TvD1。它在体外条件下显示出增强的抗真菌和黄粉虫α-淀粉酶抑制活性。在目前的研究中，我们在转基因烟草植物中比较了 α-TvD1 与天然 TvD1 的抗真菌和抗昆虫活性。α-TvD1 转基因植物对卵菌病原体寄生疫霉变种表现出增强的耐受性。nicotianae 和真菌病原体 Alternaria alternata 和 Rhizoctonia solani。此外，它对杂食性草食动物斜纹夜蛾的 1 龄和 2 龄幼虫表现出增强的抗昆虫活性。这些结果表明，α-TvD1 似乎是一种有效的抗菌基因，可用于产生对许多植物病原体和害虫具有增强抗性的优良转基因作物。nicotianae 和真菌病原体 Alternaria alternata 和 Rhizoctonia solani。此外，它对杂食性草食动物斜纹夜蛾的 1 龄和 2 龄幼虫表现出增强的抗昆虫活性。这些结果表明，α-TvD1 似乎是一种有效的抗菌基因，可用于产生对许多植物病原体和害虫具有增强抗性的优良转基因作物。nicotianae 和真菌病原体 Alternaria alternata 和 Rhizoctonia solani。此外，它对杂食性草食动物斜纹夜蛾的 1 龄和 2 龄幼虫表现出增强的抗昆虫活性。这些结果表明，α-TvD1 似乎是一种有效的抗菌基因，可用于产生对许多植物病原体和害虫具有增强抗性的优良转基因作物。