Genetics: Early Online, published on May 20, 2020 as 10.1534/genetics.120.303199 1 1 A Decoy Library Uncovers U-box E3 Ubiquitin Ligases that Regulate Flowering Time 2 in Arabidopsis 3 4 Authors: Ann M. Feke*, Jing Hong*†, Wei Liu*, Joshua M. Gendron* 5 6 Affiliations: *Department of Molecular, Cellular, and Developmental Biology, Yale 7 University, New Haven, CT 06511, USA. 8 †School of Food Science and Engineering, South China University of Technology, 9 Guangzhou, China Copyright 2020. 2 10 Running Title: E3 Ubiquitin Ligases in Flowering Time 11 Key Words: Protein degradation, flowering time, dominant negative strategies, plant 12 biology 13 Corresponding Author: Joshua Gendron; YSB 424, 260 Whitney Avenue, New Haven, CT 14 06511; 203-432-7317;
[email protected] 3 15 ABSTRACT 16 Targeted degradation of proteins is mediated by E3 ubiquitin ligases and is 17 important for the execution of many biological processes. Redundancy has prevented the 18 genetic characterization of many E3 ubiquitin ligases in plants. Here, we performed a 19 reverse genetic screen in Arabidopsis using a library of dominant negative U-box type E3 20 ubiquitin ligases in order to identify their roles in flowering time and reproductive 21 development. We identified five U-box decoy transgenic populations that have defects in 22 flowering time or the floral development program. We used additional genetic and 23 biochemical studies to validate PLANT U-BOX 14 (PUB14), MOS4-ASSOCIATED COMPLEX 3A 24 (MAC3A), and MAC3B as bona fide regulators of flowering time. This work demonstrates the 25 widespread importance of E3 ubiquitin ligases in floral reproductive development.