Central News Agency (CNA Taipei, July 2) A research team from National Central University (NCU) has discovered a plant heat tolerance mechanism linked to the synergistic action of the nuclear E3 ubiquitin ligase PUB49 and the heat tolerance protein HIT4. This finding could lead to the development of molecular targets to enhance agricultural production resilience and cope with global climate change. NCU announced in a press release today that the research team, comprising Professor Shao-Chieh Wu and PhD student Chia-Jung Wu from the Department of Life Sciences, has for the first time identified the synergistic action of PUB49 and HIT4. By regulating chromatin structure remodeling, they have successfully unveiled a crucial key mechanism behind plant heat tolerance responses. The research findings have been published in the international journal Journal of Experimental Botany. The research team used over 100,000 Arabidopsis thaliana seeds, screening for heat-intolerant mutants from a large population to identify key genes controlling heat tolerance. The most significant innovation of this research is the discovery that PUB49 is not only a new member of the plant heat tolerance pathway but also the world's first nuclear U-box type E3 ubiquitin ligase proven to be involved in "heat-induced chromatin remodeling." Research indicates that under normal temperatures, HIT4 and PUB49 aggregate in heterochromatic regions within the cell nucleus known as "chromatin centers." When plants are exposed to high temperatures, the two proteins synergistically loosen the chromatin centers and then move together to the nucleolus, thereby activating heat tolerance genes. If the function of PUB49 or HIT4 is absent, this remodeling process cannot be completed, and the plant's tolerance to high temperatures significantly decreases. The research team used gene editing technology to create PUB49 knockout mutants, further confirming the mechanism. Professor Wu stated that with global climate cha