Joint International Research Laboratory of Metabolic & Developmental Sciences, Key Laboratory of Urban Agriculture (South) Ministry of Agriculture, Plant Biotechnology Research Center, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China.
New Phytol. 2018 Apr;218(2):567-578. doi: 10.1111/nph.15005. Epub 2018 Jan 29.
Glandular trichomes and cuticles are both specialized structures that cover the epidermis of aerial plant organs. The former are commonly regarded as 'biofactories' for producing valuable natural products. The latter are generally considered as natural barriers for defending plants against abiotic and biotic stresses. However, the regulatory network for their formation and relationship remains largely elusive. Here we identify a homeodomain-leucine zipper (HD-ZIP) IV transcription factor, AaHD8, directly promoting the expression of AaHD1 for glandular trichome initiation in Artemisia annua. We found that AaHD8 positively regulated leaf cuticle development in A. annua via controlling the expression of cuticle-related enzyme genes. Furthermore, AaHD8 interacted with a MIXTA-like protein AaMIXTA1, a positive regulator of trichome initiation and cuticle development, forming a regulatory complex and leading to enhanced transcriptional activity in regulating the expression of AaHD1 and cuticle development genes. Our results reveal a molecular mechanism by which a novel HD-ZIP IV/MIXTA complex plays a significant role in regulating epidermal development, including glandular trichome initiation and cuticle formation.
腺毛和表皮是覆盖植物气生器官表皮的两种特化结构。前者通常被认为是产生有价值天然产物的“生物工厂”。后者通常被认为是植物抵御非生物和生物胁迫的天然屏障。然而，它们的形成和关系的调控网络在很大程度上仍然难以捉摸。在这里，我们鉴定了一个 homeodomain-leucine zipper (HD-ZIP) IV 转录因子 AaHD8，它直接促进 Artemisia annua 中腺毛起始的 AaHD1 的表达。我们发现 AaHD8 通过控制角质层相关酶基因的表达，正向调控 A. annua 叶片角质层的发育。此外，AaHD8 与 MIXTA 样蛋白 AaMIXTA1 相互作用，后者是毛发生成和角质层发育的正调控因子，形成一个调控复合物，导致 AaHD1 和角质层发育基因表达的转录活性增强。我们的研究结果揭示了一种新的 HD-ZIP IV/MIXTA 复合物在调节表皮发育（包括腺毛起始和角质层形成）中发挥重要作用的分子机制。
