Research Team Led by Professor CHI Wei from the School of Life Sciences, Nanjing Normal University, Deciphers the “Coordination Code” Linking Chloroplast Development and Cell Cycle in Plants

Chloroplasts are not only the “energy factories” for photosynthesis but also “environmental sensors” that regulate overall growth. So, when seedlings emerge from soil and are exposed to light, how do chloroplasts rapidly initiate development? And how does cell division synchronize with this process? Recently, the research team led by Professor CHI Wei from the School of Life Sciences at Nanjing Normal University published an article in Nature Plants, revealing for the first time the core regulatory mechanism of a “DNA architect”—RDE (REGULATOR OF DG1 EXPRESSION). This marks Nanjing Normal University’s first research article published in Nature Plants.

 

 

For a seedling that has just broken through the soil, the first ray of sunlight not only provides energy but also serves as a developmental signal. Under this instruction, chloroplasts in plant cells begin to transform from “dormant” etioplasts into a fully functional “working” state, while the cells themselves undergo rapid expansion in size or number through cell cycle regulation. The coordination mechanism between chloroplast development and the cell cycle has long been an unsolved mystery in developmental biology. For unicellular photosynthetic organisms, a single cell typically contains only one chloroplast, which can achieve synchronization through coordinated division; however, higher plant cells contain hundreds of chloroplasts and must also undergo plastid differentiation, making the regulatory mechanism much more complex.

Using dicot cotyledon greening as a model, the research team identified a key player—the RDE protein. This protein has a special ability—it bends DNA just as an architect shapes a curved structure. Under dark conditions (e.g., when seedlings are buried in soil), the RDE protein “locks” a transcription factor called DPa (dimerization partner a) into a closed loop formed by DNA bending, making it unable to function. Once light arrives, RDE is rapidly degraded, the DNA loop is “unlocked” and the DPa transcription factor is released, ready for the next two tasks.

First task: The released DPa activates a class of EMB (EMBRYO-DEFECTIVE) genes. The proteins encoded by these genes are responsible for the synthesis of photosynthetic pigment-protein complexes within the chloroplast, directly promoting the transformation of etioplasts into chloroplasts and turning the cotyledons green.

Second task: DPa simultaneously activates key genes of the S-phase (DNA synthesis) of the cell cycle, prompting the doubling of nuclear DNA without the cell entering mitosis—a phenomenon known as endoreduplication. Endoreduplication rapidly increases cell volume without division, thereby efficiently supporting cotyledon expansion growth. Through the “function switch” of the RDE protein under light and dark conditions, together with its unique ability to reshape DNA conformation, the light signal, plastid differentiation, and cell cycle regulation are woven together into a precise coordination network.

 

Further research revealed that this mechanism is evolutionarily conserved, existing in almost all green plants. The research team also made an unexpected discovery: when the function of the RDE gene is suppressed, plant cotyledons green faster, chlorophyll content increases, and the plants even exhibit enhanced adaptability to environmental stresses such as high temperatures. This suggests that the RDE gene could become a potential target for improving crop environmental adaptability and enhancing photosynthetic efficiency in the future.

This study, titled “Conserved DNA Architect Couples Chloroplast Development to Cell Cycle in Developing Cotyledons”, was published in Nature Plants. Postdoctoral researcher WANG Xiushun from the School of Life Sciences is the first author, and Professor CHI Wei is the corresponding author of the paper. Associate Researcher JI Daili and Senior Engineer MA Jinfang from the Institute of Botany, Chinese Academy of Sciences; Dr. CHAI Xin from the China Academy of Chinese Medical Sciences; Associate Professor LI Jian and Dr. SUN Linhua from Nanjing Normal University also participated in this research. Professors YANG Chengwei from South China Normal University, YAN Shunping from Huazhong Agricultural University, and DING Zhaojun from Shandong University provided some of the research materials. Dr. ZHANG Xiaoxia from the Institute of Botany, Chinese Academy of Sciences; Associate Professor ZHANG Zhenhua, Professor ZHU Ziqiang, and Dr. WANG Qi from Nanjing Normal University provided substantial assistance during the research process. This work was supported by the National Key Research and Development Program, Nature Science Foundation of China, the Natural Science Foundation of Jiangsu Province, the Priority Academic Program Development of Jiangsu Higher Education Institutions, the China Postdoctoral Science Foundation, and Jiangsu Funding Program for Excellent Postdoctoral Talent.

View Full Text: https://www.nature.com/articles/s41477-026-02280-1