Manivannan Abinaya, Israni Bhawana, Luck Katrin, Götz Monika, Seibel Elena, Easson Michael L A E, Kirsch Roy, Reichelt Michael, Stein Beate, Winter Stephan, Gershenzon Jonathan, Vassão Daniel Giddings
Max Planck Institute for Chemical Ecology, Jena, Germany.
Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany.
Front Plant Sci. 2021 Jun 4;12:671286. doi: 10.3389/fpls.2021.671286. eCollection 2021.
Cruciferous plants in the order Brassicales defend themselves from herbivory using glucosinolates: sulfur-containing pro-toxic metabolites that are activated by hydrolysis to form compounds, such as isothiocyanates, which are toxic to insects and other organisms. Some herbivores are known to circumvent glucosinolate activation with glucosinolate sulfatases (GSSs), enzymes that convert glucosinolates into inactive desulfoglucosinolates. This strategy is a major glucosinolate detoxification pathway in a phloem-feeding insect, the silverleaf whitefly , a serious agricultural pest of cruciferous vegetables. In this study, we identified and characterized an enzyme responsible for glucosinolate desulfation in the globally distributed species MEAM1. In assays, this sulfatase showed a clear preference for indolic glucosinolates compared with aliphatic glucosinolates, consistent with the greater representation of desulfated indolic glucosinolates in honeydew. might use this detoxification strategy specifically against indolic glucosinolates since plants may preferentially deploy indolic glucosinolates against phloem-feeding insects. silencing of the expression of the GSS gene via RNA interference led to lower levels of desulfoglucosinolates in honeydew. Our findings expand the knowledge on the biochemistry of glucosinolate detoxification in phloem-feeding insects and suggest how detoxification pathways might facilitate plant colonization in a generalist herbivore.
硫代葡萄糖苷是含硫的前体毒性代谢物，通过水解被激活形成异硫氰酸酯等化合物，这些化合物对昆虫和其他生物有毒。已知一些食草动物会用硫代葡萄糖苷硫酸酯酶（GSSs）规避硫代葡萄糖苷的激活，硫代葡萄糖苷硫酸酯酶可将硫代葡萄糖苷转化为无活性的脱硫硫代葡萄糖苷。这种策略是一种吸食韧皮部的昆虫——烟粉虱（十字花科蔬菜的一种严重农业害虫）中主要的硫代葡萄糖苷解毒途径。在本研究中，我们鉴定并表征了一种在全球分布的烟粉虱MEAM1品系中负责硫代葡萄糖苷脱硫的酶。在实验中，与脂肪族硫代葡萄糖苷相比，这种硫酸酯酶对吲哚族硫代葡萄糖苷表现出明显的偏好，这与蜜露中脱硫吲哚族硫代葡萄糖苷的含量更高一致。烟粉虱可能专门针对吲哚族硫代葡萄糖苷使用这种解毒策略，因为植物可能优先利用吲哚族硫代葡萄糖苷来对付吸食韧皮部的昆虫。通过RNA干扰沉默GSS基因的表达会导致蜜露中脱硫硫代葡萄糖苷水平降低。我们的研究结果扩展了对吸食韧皮部昆虫中硫代葡萄糖苷解毒生物化学的认识，并揭示了解毒途径可能如何促进多食性食草动物对植物的侵害。
