SOBIR1/EVR prevents precocious initiation of fiber differentiation during wood development through a mechanism involving BP and ERECTA

First author: Ana Milhinhos; Affiliations: University of Oxford (牛津大学): Oxford, UK

Corresponding author: Javier Agustí

In plants, secondary growth results in radial expansion of stems and roots, generating large amounts of biomass in the form of wood. Using genome-wide association studies (GWAS)-guided reverse genetics in Arabidopsis thaliana, we discovered SOBIR1/EVR, previously known to control plant immunoresponses and abscission, as a regulator of secondary growth. We present anatomical, genetic, and molecular evidence indicating that SOBIR1/EVR prevents the precocious differentiation of xylem fiber, a key cell type for wood development. SOBIR1/EVR acts through a mechanism that involves BREVIPEDICELLUS (BP) and ERECTA (ER), 2 proteins previously known to regulate xylem fiber development. We demonstrate that BP binds SOBIR1/EVR promoter and that SOBIR1/EVR expression is enhanced in bp mutants, suggesting a direct, negative regulation of BP over SOBIR1/EVR expression. We show that SOBIR1/EVR physically interacts with ER and that defects caused by the sobir1/evr mutation are aggravated by mutating ER, indicating that SOBIR1/EVR and ERECTA act together in the control of the precocious formation of xylem fiber development.

植物中，次生生长会增加茎和根的径向扩张，从而通过木材的形式产生大量的生物量。利用全基因组关联分析指导的反向遗传学方法，作者发现拟南芥SOBIR1/EVR基因不仅具有先前所认为的控制植物免疫响应和脱落的功能，同时还参与了植物的次生生长调控。作者通过结构解剖、遗和分子方面的试验证据揭示了SOBIR1/EVR蛋白能够防止木质部纤维的过早分化，而该细胞类型对于木材的发育至关重要。SOBIR1/EVR蛋白通过BP和ER发挥其作用，而这两个蛋白已经被报道具有木质部纤维发育调控的功能。进一步的研究显示BP能够结合到SOBIR1/EVR基因的启动子区，并且在bp突变体中，SOBIR1/EVR基因的表达得到了增强，说明BP对于SOBIR1/EVR基因的表达具有直接的负调控作用。另外，SOBIR1/EVR蛋白能够在物理上与ER蛋白互作，并且sobir1/evr突变体的缺陷表型在突变ER后进一步加强，说明SOBIR1/EVR和ERECTA共同调控木质部纤维发育的过早形成。

通讯：Javier Agustí（https://agustilab.wordpress.com)

个人简介：2003-2007年，瓦伦西亚理工大学，博士；2007-2012年，奥地利维也纳孟德尔分子植物研究所，博士后。

研究方向：植物的横向生长。

doi: https://doi.org/10.1073/pnas.1807863116

Journal: PNAS

First Published: August 23, 2019