Qa-SNARE Protein SYP22 Negatively Regulates Brassinosteroid Signaling in the Dark

• Published in: Acta biologica cracoviensia. Series Botanica. 2015-12, Vol.57 (2), p.79-88
• Main Authors: Yao, Ting Shan, Zhu, Xiao Feng, Jung, Jin Hee, Xuan, Yuan Hu
• Format: Article
• Language: English
• Subjects: dark; SNARE; trafficking
• ISSN: 1898-0295; 1898-0295
• DOI: 10.1515/abcsb-2015-0021

Soluble N-ethyl-maleimide sensitive factor attachment adaptor protein receptor (SNARE) domain-containing proteins were mainly involved in vesicle-associated membrane fusion. Genetic screening has revealed the function of SNARE in different aspects of plant biology. Among them, Synthaxin-22 (SYP22) a Qa-SNARE has been reported to have a pleiotropic function in plant development including regulation of leaf waving, shoot gravitropism and flowering time. In this study, we identified a new role of SYP22 in regulation of brassinosteroid (BR) signaling, especially in the dark. SYP22 interacts with BR receptor, brassinosteroid insensitive 1 (BRI1), and overexpression of SYP22 enhanced a weak BRI1 mutant phenotype. mutant exhibits short hypocotyl and it is sensitive to exogenously treated BR while slightly insensitive to BR-biosynthesis inhibitor propiconazole (PCZ) in the dark. Expression levels of BR signaling maker genes , and were slightly higher, while , a BR biosynthesis marker gene, was lower in compared to the wild-type. In addition, was sensitive to 2,4-D, a synthetic auxin, in the dark. In conclusion, SYP22 is involved in BR- and auxin-mediated hypocotyl growth inhibition in the dark, which might be via interaction with BR and auxin key regulators to alter their internalization in