Location: Plant, Soil and Nutrition ResearchTitle: ORANGE represses chloroplast biogenesis in etiolated Arabidopsis Cotyledons via interacting with TCP14
|SUN, TIANHU - Cornell University - New York|
|ZHOU, FEI - Nanjing University|
|HUANG, XING-QI - Nanjing University|
|CHEN, WEI-CAI - Nanjing University|
|KONG, MENG-JUAN - Nanjing University|
|ZHOU, CHANG-FANG - Nanjing University|
|ZHUANG, ZHONG - Nanjing University|
|LU, SHAN - Nanjing University|
Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2019
Publication Date: 10/11/2019
Citation: Sun, T., Zhou, F., Huang, X., Chen, W., Kong, M., Zhou, C., Zhuang, Z., Li, L., Lu, S. 2019. ORANGE represses chloroplast biogenesis in etiolated Arabidopsis Cotyledons via interacting with TCP14. The Plant Cell. 31:2996-3014.
Interpretive Summary: The formation of chloroplasts in germinating cotyledons is crucially important for higher plants to adapt for growth under light. Previously, we found that an ORANGE (OR) protein initiates the formation of carotenoid-accumulating plastids by promoting carotenoid formation and stable storage. In this study, we report that OR physically interacts with TCP14 transcription factor in the nuclei. Through this interaction, the nucleus-localized OR suppresses chlorophyll pathway gene expression and delays chloroplast development in the dark germinating cotyledons. The shift of OR localization from the nuclei to chloroplasts upon exposing to light facilitates chloroplast formation in the germinating seedlings. Our findings provide new insights into the control of early chloroplast development, and consequent plant adaption for growth under light.
Technical Abstract: The conversion of etioplasts into chloroplasts in germinating cotyledons is a crucial transition for higher plants, enabling photoautotrophic growth upon illumination. Tight coordination of chlorophyll biosynthesis and photosynthetic complex assembly is critical for this process. ORANGE (OR), a DnaJ-like zinc finger domain-containing protein, was reported to trigger the biogenesis of carotenoid-accumulating plastids by promoting carotenoid biosynthesis and sequestration. Both nuclear and plastidic localizations of OR have been observed. Here, we show that OR physically interacts with the transcription factor TCP14 in the nucleus, and represses its transactivation activity. Through this interaction, the nucleus-localized OR negatively regulates expression of EARLY LIGHT-INDUCIBLE PROTEINS (ELIPs), reduces chlorophyll biosynthesis and delays the development of thylakoid membranes in the plastids of germinating cotyledons. Nuclear abundance of OR decreased upon illumination. Together with an accumulation of TCP14 in the nucleus, this derepresses chloroplast biogenesis during de-etiolation. TCP14 is epistatic to OR and expression of ELIPs is directly regulated by the binding of TCP14 to Up1 elements in the ELIP promoter regions. Our results demonstrate that the interaction between OR and TCP14 in the nucleus leads to repression of chloroplast biogenesis in etiolated seedlings and provide new insights into the regulation of early chloroplast development.