OsHSD1, a hydroxysteroid dehydrogenase, is involved in cuticle formation and lipid homeostasis in rice

• Published in: Plant science (Limerick) Vol. 249; pp. 35 - 45
• Main Authors: Zhang, Zhe, Cheng, Zhi-jun, Gan, Lu, Zhang, Huan, Wu, Fu-qing, Lin, Qi-bing, Wang, Jiu-lin, Wang, Jie, Guo, Xiu-ping, Zhang, Xin, Zhao, Zhi-chao, Lei, Cai-lin, Zhu, Shan-shan, Wang, Chun-ming, Wan, Jian-min
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.08.2016
• Subjects: Chromosome Mapping; Cloning, Molecular; Cuticular wax; Hydroxysteroid dehydrogenase; Hydroxysteroid Dehydrogenases - genetics; Hydroxysteroid Dehydrogenases - metabolism; Hydroxysteroid Dehydrogenases - physiology; Lipid; Lipid Metabolism - genetics; Oil body; Oryza - enzymology; Oryza - genetics; Oryza - metabolism; Oryza sativa; Phenotype; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Proteins - physiology; Oryza sativa; Hydroxysteroid dehydrogenase; Cuticular wax; Lipid; Oil body
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2016.05.005

•A rice mutant, named oshsd1, exhibits defects in cuticle formation.•OsHSD1 mutation caused accumulation of fatty acids in rice leaves.•OsHSD1 protein is the first to target oil body in rice.•OsHSD1 is involved in cuticle formation and lipid homeostasis, probably by mediating sterol signaling. Cuticular wax, a hydrophobic layer on the surface of all aerial plant organs, has essential roles in plant growth and survival under various environments. Here we report a wax-deficient rice mutant oshsd1 with reduced epicuticular wax crystals and thicker cuticle membrane. Quantification of the wax components and fatty acids showed elevated levels of very-long-chain fatty acids (VLCFAs) and accumulation of soluble fatty acids in the leaves of the oshsd1 mutant. We determined the causative gene OsHSD1, a member of the short-chain dehydrogenase reductase family, through map-based cloning. It was ubiquitously expressed and responded to cold stress and exogenous treatments with NaCl or brassinosteroid analogs. Transient expression of OsHSD1-tagged green fluorescent protein revealed that OsHSD1 localized to both oil bodies and endoplasmic reticulum (ER). Dehydrogenase activity assays demonstrated that OsHSD1 was an NAD+/NADP+-dependent sterol dehydrogenase. Furthermore, OsHSD1 mutation resulted in faster protein degradation, but had no effect on the dehydrogenase activity. Together, our data indicated that OsHSD1 plays a specialized role in cuticle formation and lipid homeostasis, probably by mediating sterol signaling. This work provides new insights into oil-body associated proteins involved in wax and lipid metabolism.