Four Closely-related RING-type E3 Ligases, APD1-4, are Involved in Pollen Mitosis II Regulation in Arabidopsis

• Published in: Journal of integrative plant biology 2012-10, Vol.54 (10), p.814-827
• Main Authors: Luo, Guo, Gu, Hongya, Liu, Jingjing, Qu, Li‐Jia
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis; Arabidopsis - cytology; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; E3 ligase; gametogenesis; genes; ligases; Male gametogenesis; mitosis; Mitosis - physiology; Molecular Sequence Data; mutants; pathogens; phenotype; photomorphogenesis; pollen; Pollen - cytology; Pollen - enzymology; Pollen - genetics; pollen mitosis II; proteins; RING-finger; RNA interference; Sequence Homology, Amino Acid; Ubiquitin-Protein Ligases - chemistry; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; 拟南芥; 有丝分裂; 花粉; 蛋白质相互作用; 调控机制; 连接酶; 雄配子发育; 雪崩光电二极管
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/j.1744-7909.2012.01152.x

Ubiquitination of proteins is one of the critical regulatory mechanisms in eukaryotes. In higher plants, protein ubiquitination plays an essential role in many biological processes, including hormone signaling, photomorphogenesis, and pathogen defense. However, the roles of protein ubiquitination in the reproductive process are not clear. In this study, we identified four plant‐specific RING‐finger genes designated Aberrant Pollen Development 1 (APD1) to APD4, as regulators of pollen mitosis II (PMII) in Arabidopsis thaliana (L.). The apd1 apd2 double mutant showed a significantly increased percentage of bicellular‐like pollen at the mature pollen stage. Further downregulation of the APD3 and APD4 transcripts in apd1 apd2 by RNA interference (RNAi) resulted in more severe abnormal bicellular‐like pollen phenotypes than in apd1 apd2, suggesting that cell division was defective in male gametogenesis. All of the four genes were expressed in multiple stages at different levels during male gametophyte development. Confocal analysis using green florescence fusion proteins (GFP) GFP‐APD1 and GFP‐APD2 showed that APDs are associated with intracellular membranes. Furthermore, APD2 had E2‐dependent E3 ligase activity in vitro, and five APD2‐interacting proteins were identified. Our results suggest that these four genes may be involved, redundantly, in regulating the PMII process during male gametogenesis.