MetaboLights MTBLS1383 - GNPS Endoplasmic reticulum-derived bodies enable a single-cell chemical defense in Brassicaceae plants

Brassicaceae plants have a dual-cell type of chemical defense against herbivory. Here we show a novel single-cell defense involving endoplasmic reticulum (ER)-derived organelles (ER bodies) and the vacuoles. We identify various glucosinolates as endogenous substrates of the ER-body ?-glucosidases BGLU23 and BGLU21. Woodlice strongly prefer to eat seedlings of bglu23 bglu21 or a glucosinolate-deficient mutant over wild-type seedlings, confirming that the ?-glucosidases have a role in chemical defense: production of toxic compounds upon organellar damage. Deficiency of the Brassicaceae-specific protein NAI2 prevents ER-body formation, which results in a loss of BGLU23 and a loss of resistance to woodlice. Hence, NAI2 that interacts with BGLU23 is essential for sequestering BGLU23 in ER bodies and preventing its degradation. Artificial expression of NAI2 and BGLU23 in non-Brassicaceae plants results in the formation of ER bodies, indicating that acquisition of NAI2 by Brassicaceae plants is a key step in developing their single-cell defense system.

十字花科（Brassicaceae）植物对植食动物具备双细胞型化学防御机制。本研究揭示了一种全新的单细胞防御策略，该策略依赖于内质网（endoplasmic reticulum, ER）衍生的细胞器——ER体（ER bodies）与液泡协同发挥作用。研究人员鉴定出多种硫代葡萄糖苷作为ER体β-葡萄糖苷酶BGLU23与BGLU21的内源性底物。实验发现，潮虫更偏好取食bglu23 bglu21双突变体或硫代葡萄糖苷缺陷型突变体的幼苗，而非野生型幼苗，这证实了β-葡萄糖苷酶在化学防御中的功能：即细胞器受损时可产生活性毒性化合物。十字花科特异性蛋白NAI2的缺失会阻断ER体的形成，进而导致BGLU23蛋白缺失以及对潮虫的抗性丧失。由此可见，与BGLU23互作的NAI2对于将BGLU23封存于ER体中并防止其降解至关重要。在非十字花科植物中人工表达NAI2与BGLU23可诱导ER体的形成，这表明十字花科植物获取NAI2是其演化出单细胞防御系统的关键步骤。