SIZ1-mediated SUMOlation of CPSF100 promotes plant thermomorphogenesis by controlling alternative polyadenylation

Abstract

Under warm temperatures, plants adjust their morphologies for environmental adaption via precise gene expression regulation. However, the function and regulation of alternative polyadenylation (APA), an important fine-tuning of gene expression, remains unknown in plant thermomorphogenesis. Here we found that SUMOylation, a critical post-translational modification, was induced under a long-time treatment at warm temperatures mediated by a SUMO ligase SIZ1 in Arabidopsis. Depletion of SIZ1 altered the global usage of polyadenylation signals and affected the APA dynamic of thermomorphogenesis genes. CPSF100, a key subunit of the CPSF complex for polyadenylation regulation, was SUMOylated via SIZ1. Importantly, SUMOylation was essential for the function of CPSF100 in genome-wide polyadenylation site choice during thermomorphogenesis. The SUMO conjugation on CPSF100 attenuated its interaction with two isoforms of its partner CPSF30, increasing the nuclear accumulation of CPSF100 for polyadenylation regulation. In summary, we uncovered the mechanism for the regulation of APA via SUMOylation in plant thermomorphogenesis.