Scientists Uncover Plant Heat Tolerance Mechanism Amid Global Warming Fears

A research team from National Central University has successfully unveiled a critical mechanism plants employ to withstand high temperatures, a discovery with significant implications for food security in the face of escalating global warming. The study, published in the international journal *Journal of Experimental Botany*, details how the nuclear E3 ubiquitin ligase PUB49 and heat tolerance protein HIT4 work together to regulate plant heat responses.

Professor Shao-chieh Wu and PhD student Chia-jung Wu led the research, which utilized over 100,000 *Arabidopsis thaliana* seeds. Through forward genetic screening, they identified key genes controlling heat tolerance. Their breakthrough lies in identifying PUB49 as the first nuclear U-box type E3 ubiquitin ligase globally proven to be involved in "heat-induced chromatin remodeling." This challenges the previous understanding that ubiquitination primarily handles protein degradation and quality control.

The research establishes a vital link between "ubiquitination regulation, chromatin remodeling, and heat tolerance," opening new avenues in plant stress biology. Under normal temperatures, HIT4 and PUB49 gather in the nucleus's heterochromatin regions. Upon heat stimulation, they cooperate to loosen these chromatin structures, allowing heat tolerance genes to be activated. Without PUB49 or HIT4, this process is disrupted, significantly reducing the plant's ability to survive heat.

Further experiments using CRISPR/Cas9 gene editing confirmed PUB49's role. While PUB49-deficient mutant plants grew normally at ambient temperatures, they could not survive at 37°C, exhibiting the same heat sensitivity as HIT4 mutants. This demonstrates how plant cells use ubiquitination signals to alter chromatin structure and enhance high-temperature adaptation. The findings offer new molecular targets for developing heat-resistant crops, bolstering agricultural resilience against climate change.

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This discovery provides new molecular targets for developing heat-resistant crops, bolstering agricultural resilience against climate change.