摘要
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 repro- ductive 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 apdl 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 apdl apd2 by RNA interference （RNAi） resulted in more severe abnormal bicellular-like pollen phenotypes than in apdl 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.
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 repro- ductive 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 apdl 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 apdl apd2 by RNA interference （RNAi） resulted in more severe abnormal bicellular-like pollen phenotypes than in apdl 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.
基金
supported by the National Key Basic Research Program of the People's Republic of China(2011CB915402)
the National Science Foundation of China(30970270to JJL)
