J Integr Plant Biol ›› 2017, Vol. 59 ›› Issue (1): 15-29.DOI: 10.1111/jipb.12509

• Cell and Developmental Biology • Previous Articles     Next Articles

Arabidopsis SUMO protease ASP1 positively regulates flowering time partially through regulating FLC stability

Xiangxiong Kong1,2, Xi Luo1,2, Gao-Ping Qu1,2, Peng Liu1† and Jing Bo Jin1*   

  1. 1Key Laboratory of Plant Molecular Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing, China
    2Graduate School of the Chinese Academy of Sciences, Beijing, China
  • Received:2016-08-17 Accepted:2016-12-05 Published:2016-12-07
  • About author:Current address: Division of Biological Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
    *Correspondence: E-mail: Jing Bo Jin (jinjb@ibcas.ac.cn)

Abstract:

The initiation of flowering is tightly regulated by the endogenous and environment signals, which is crucial for the reproductive success of flowering plants. It is well known that autonomous and vernalization pathways repress transcription of FLOWERING LOCUS C (FLC), a focal floral repressor, but how its protein stability is regulated remains largely unknown. Here, we found that mutations in a novel Arabidopsis SUMO protease 1 (ASP1) resulted in a strong late-flowering phenotype under long-days, but to a lesser extent under short-days. ASP1 localizes in the nucleus and exhibited a SUMO protease activity in vitro and in vivo. The conserved Cys-577 in ASP1 is critical for its enzymatic activity, as well as its physiological function in the regulation of flowering time. Genetic and gene expression analyses demonstrated that ASP1 promotes transcription of positive regulators of flowering, such as FT, SOC1 and FD, and may function in both CO-dependent photoperiod pathway and FLC-dependent pathways. Although the transcription level of FLC was not affected in the loss-of-function asp1 mutant, the protein stability of FLC was increased in the asp1 mutant. Taken together, this study identified a novel bona fide SUMO protease, ASP1, which positively regulates transition to flowering at least partly by repressing FLC protein stability.

SUMOylation is a rapid post-translational modification, which can be reversed by SUMO proteases. Arabidopsis contains more than 60 putative SUMO proteases, but their biological functions remain largely unknown. This study identified a novel SUMO protease, ASP1, which positively regulate transition to flowering partly by repressing FLC protein stability.

Key words: CONSTANS, FLOWERING LOCUS C, flowering time, small ubiquitin-related modifier (SUMO), SUMO protease

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