Plant Hormones Help Tomato Plants Survive Cold by Breaking Down Damaged Proteins

Jenn Hoskins
19th August, 2024

Plant Hormones Help Tomato Plants Survive Cold by Breaking Down Damaged Proteins

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Zhejiang University found that strigolactones help tomato plants tolerate cold by regulating autophagy and protein degradation
  • Cold stress causes an accumulation of damaged proteins in tomato plants, which strigolactones help reduce by enhancing autophagy
  • The study identified that the transcription factor HY5, activated by strigolactones, is crucial for initiating autophagy and improving cold tolerance in tomatoes
The study conducted by researchers at Zhejiang University[1] delves into the intricate relationship between autophagy—a process involved in protein degradation and amino acid recycling—and phytohormones in tomato plants under cold stress conditions. This research is critical as it uncovers how strigolactones, a type of phytohormone, regulate autophagy and the degradation of ubiquitinated proteins, thereby enhancing cold tolerance in tomatoes. Autophagy is a cellular process that breaks down and recycles redundant or damaged cellular components, and it plays a significant role in plant development and stress responses[2]. However, the specific mechanisms through which phytohormones influence autophagy, especially under stress conditions, have been largely unexplored until now. The researchers employed a variety of advanced techniques, including CRISPR/Cas9 gene editing, ultra-performance liquid chromatography coupled with tandem mass spectrometry, chromatin immunoprecipitation, electrophoretic mobility shift assays, and dual-luciferase assays to uncover the molecular mechanisms at play. The study found that cold stress leads to the accumulation of ubiquitinated proteins in tomato plants. Ubiquitinated proteins are those tagged for degradation by the ubiquitin-proteasome system, a crucial cellular pathway for maintaining protein quality and regulating various cellular processes[3]. In this context, the accumulation of these proteins indicates a disruption in their normal degradation process, which can be detrimental to the plant's health. Interestingly, mutants deficient in strigolactone biosynthesis were more sensitive to cold stress and showed increased levels of ubiquitinated proteins. On the other hand, treatment with a synthetic strigolactone analog, GR245DS, enhanced cold tolerance in tomato plants. This treatment led to elevated levels of autophagosomes (structures involved in autophagy) and increased expression of autophagy-related genes (ATGs), along with a reduction in the accumulation of ubiquitinated proteins. A key finding of the study is the role of ELONGATED HYPOCOTYL 5 (HY5) in this process. Cold stress induced the accumulation of HY5, a transcription factor, which was further triggered by strigolactones. HY5 then trans-activated the transcription of ATG18a, a gene crucial for autophagy formation. Mutation of ATG18a compromised the cold tolerance induced by strigolactones, leading to decreased autophagosome formation and increased accumulation of ubiquitinated proteins. This study ties together previous findings on the importance of autophagy in stress responses and nutrient recycling in plants[2]. It also builds on the understanding of how light and cold signals integrate to enhance freezing tolerance through the stabilization of HY5[4]. By demonstrating that strigolactones positively regulate autophagy in an HY5-dependent manner, this research provides a comprehensive view of how phytohormones can modulate cellular processes to enhance stress tolerance. In summary, the findings from Zhejiang University reveal a novel mechanism by which strigolactones enhance cold tolerance in tomato plants through the regulation of autophagy and the degradation of ubiquitinated proteins. This research not only advances our understanding of plant stress responses but also opens up potential avenues for developing cold-tolerant crops through the manipulation of strigolactone pathways.

GeneticsBiochemPlant Science

References

Main Study

1) Strigolactones positively regulate HY5-dependent autophagy and the degradation of ubiquitinated proteins in response to cold stress in tomato.

Published 19th August, 2024

https://doi.org/10.1111/nph.20058

Related Studies

2) Autophagic pathway contributes to low-nitrogen tolerance by optimizing nitrogen uptake and utilization in tomato.

https://doi.org/10.1093/hr/uhac068

3) Impairment of the ubiquitin-proteasome system by protein aggregation.

Journal: Science (New York, N.Y.), Issue: Vol 292, Issue 5521, May 2001

4) Integration of low temperature and light signaling during cold acclimation response in Arabidopsis.

https://doi.org/10.1073/pnas.1107161108


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