Plants live as sessile organisms with large-scale gene duplication events and subsequent paralogue divergence during evolution. Notably, plant paralogues are expressed tissue-specifically and fine-tuned by phytohormones during various developmental processes. The coat protein complex II (COPII) is a highly conserved vesiculation machinery mediating protein transport from the endoplasmic reticulum to the Golgi apparatus in eukaryotes¹. Intriguingly, Arabidopsis COPII paralogues greatly outnumber those in yeast and mammals^2,3,4,5,6. However, the functional diversity and underlying mechanism of distinct COPII paralogues in regulating protein endoplasmic reticulum export and coping with various adverse environmental stresses are poorly understood. Here we characterize a novel population of COPII vesicles produced in response to abscisic acid, a key phytohormone regulating abiotic stress responses in plants. These hormone-induced giant COPII vesicles are regulated by an Arabidopsis-specific COPII paralogue and carry stress-related channels/transporters for alleviating stresses. This study thus provides a new mechanism underlying abscisic acid-induced stress responses via the giant COPII vesicles and answers a long-standing question on the evolutionary significance of gene duplications in Arabidopsis.

植物作为固着生物存在，在进化过程中会发生大规模的基因复制事件和随后的旁系同源物分化。值得注意的是，植物旁系同源物在各种发育过程中通过植物激素进行组织特异性表达和微调。外壳蛋白复合物 II (COPII) 是一种高度保守的囊泡形成机制，介导蛋白质从内质网转运到真核生物中的高尔基体¹。有趣的是，拟南芥COPII 旁系同源物的数量大大超过酵母和哺乳动物中的旁系同源物^2,3,4,5,6. 然而，人们对不同 COPII 旁系同源物在调节蛋白质内质网输出和应对各种不利环境胁迫方面的功能多样性和潜在机制知之甚少。在这里，我们描述了响应脱落酸而产生的新型 COPII 囊泡群，脱落酸是一种调节植物非生物胁迫反应的关键植物激素。这些激素诱导的巨大 COPII 囊泡受拟南芥特异性 COPII 旁系同源物调节，并携带压力相关通道/转运蛋白以减轻压力。因此，这项研究提供了一种新机制，通过巨大的 COPII 囊泡引起脱落酸诱导的应激反应，并回答了一个长期存在的关于拟南芥基因复制的进化意义的问题。