Yu Chao-Yuan, Sharma Oshin, Nguyen Phong H T, Hartono Chynthia D, Kanehara Kazue
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan.
Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, 11529, Taiwan.
Plant J. 2021 Nov;108(4):992-1004. doi: 10.1111/tpj.15487. Epub 2021 Oct 28.
SMALLER TRICHOMES WITH VARIABLE BRANCHES (SVB) is an emerging plant growth regulator in trichome development, endoplasmic reticulum stress response, and phosphoinositide signaling, and belongs to the land plant-specific DUF538 domain-containing protein family. Despite its multifaceted roles, the functions of this protein family are poorly understood in plant growth and development. Here, we report that SVB-like (SVBL), the closest homolog of SVB, modulates plant growth and trichome development with SVB in Arabidopsis thaliana. Although none of the single mutants showed an obvious growth defect, the double mutants of svb svbl exhibited dwarfed plant growth. In trichome development, the defects in svb mutant were greatly enhanced by the additional mutation in SVBL, despite the single knockout of SVBL showing the mild defects. The double mutation reduced the transcript level of one of the central hub genes for trichome development, GLABRA1 (GL1), which in turn affects the other downstream genes, GLABRA2 (GL2), TRANSPARENT TESTA GLABRA2 (TTG2), TRIPTYCHON (TRY), CAPRICE (CPC), and ENHANCER OF TRY AND CPC1 (ETC1). In situ translational reporter assays showed that SVB and SVBL share highly similar localization patterns both at tissue and subcellular levels. The present study suggests that SVB and SVBL play a pivotal role in plant growth and trichome development by affecting a specific subset of known trichome developmental regulators, highlighting the importance of the DUF538 protein family in higher plants.
具有可变分支的小腺毛（SVB）是一种在腺毛发育、内质网应激反应和磷酸肌醇信号传导中新兴的植物生长调节剂，属于陆地植物特有的含DUF538结构域的蛋白家族。尽管其具有多方面的作用，但该蛋白家族在植物生长发育中的功能仍知之甚少。在此，我们报道SVB的最接近同源物——类SVB（SVBL），在拟南芥中与SVB共同调节植物生长和腺毛发育。虽然单个突变体均未表现出明显的生长缺陷，但svb svbl双突变体表现出植株生长矮小。在腺毛发育过程中，尽管SVBL单敲除表现出轻微缺陷，但SVBL的额外突变极大地增强了svb突变体的缺陷。双突变降低了腺毛发育的核心枢纽基因之一GLABRA1（GL1）的转录水平，进而影响其他下游基因，如GLABRA2（GL2）、透明种皮GLABRA2（TTG2）、三联体（TRY）、任性（CPC）和TRY与CPC1增强子（ETC1）。原位翻译报告分析表明，SVB和SVBL在组织和亚细胞水平上具有高度相似的定位模式。本研究表明，SVB和SVBL通过影响已知腺毛发育调节因子的特定子集，在植物生长和腺毛发育中起关键作用，突出了DUF538蛋白家族在高等植物中的重要性。
