Global warming poses a severe threat to crop productivity by inhibiting photosynthetic efficiency under heat stress, yet the molecular mechanisms remain poorly understood. On March 22, 2025, a groundbreaking study led by Dr. Xiaofeng Fang’s group at the School of Life Sciences, Tsinghua University, was published in Nature Communications. The research uncovers how the chloroplast-localized MORF8 protein forms solid-like condensates under heat stress, disrupting RNA editing and impairing photosynthesis.
Titled “Solid-like condensation of MORF8 inhibits RNA editing under heat stress in Arabidopsis,” the research demonstrates that MORF8 undergoes phase separation under high temperatures, recruiting key RNA editing factors, including pentatricopeptide repeat (PPR) proteins, into condensates. This sequestration weakens PPR proteins’ ability to bind target RNAs, reducing editing efficiency at critical sites such as ndhD-2. Consequently, the activity of photosynthetic membrane complexes (e.g., NDH-PSI) declines, leading to reduced photosynthetic efficiency (Figure 1).
Figure 1. A working model for MORF8 condensation in RNA editing regulation under heat stress.
The key findings of this study include:
1. Heat-Induced Condensates: MORF8 forms solid-like condensates in response to heat stress, as confirmed by experiments in Arabidopsis and tobacco.
2. Recruitment of Editing Factors: These condensates selectively recruit MORF2, MORF9, and PPR proteins, impairing their RNA-binding capacity.
3. Negative Correlation: The number of MORF8 condensates inversely correlates with ndhD-2 editing efficiency during heat treatment and recovery.
4. Evolutionary Conservation: Homologs of MORF8 in rice and soybean exhibit similar heat-responsive condensation, suggesting a conserved mechanism across crops and angiosperms.
This study is the first to link protein phase separation to plant heat stress responses, expanding the functional understanding of biomolecular condensates in plants. The proposed “sequester-and-inhibit” model provides a novel framework for studying stress adaptation. Furthermore, the conservation of MORF8 highlights its potential as a molecular target for engineering heat-resistant crops to safeguard food security.
Dr. Xiaofeng Fang is the corresponding author and postdoctoral researcher Dr. Wu Jie is the first author. Prof. Yang Wenqiang and Dr. Wang Yue from the Chinese Academy of Sciences, Prof. Chen Haodong (Tsinghua University), and Prof. Xu Tongda (Fujian Agriculture and Forestry University) are especially acknowledged for their help and advice. The research was supported by the National Natural Science Foundation of China and the Ministry of Science and Technology’s Key R&D Program.
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Editor: Li Han
