Thermopriming: The future of agriculture?

Grocery stores should be considered a privilege because they allow us to forget where our food comes from. How often do you actually think about where your produce originates? Plants are subject to the climate and changing weather patterns can significantly affect the growth process.

In my previous post, I mentioned that heat threatens plants worldwide because it can devernalize flowering plants, leading to delayed flowering and poor crop yields. However, one way this can be prevented is through thermopriming [1-4]. Thermopriming requires plants to be acclimatized to mild-high temperatures and hence offers them the ability to cope with lethal high temperatures [1]. Plants will then become thermotolerant by restructuring their energy pathways and increasing the production of metabolites that serve as antioxidants, growth precursors, and osmolytes to speed the recovery from stress, while lipid metabolites protect the cell membrane integrity [2,3]. For example, you can easily observe in the picture below that the Arabidopsis plants that were not primed before heat shock (i.e. exposure to 45°C) did not withstand the stress [3]. This experiment led researchers to believe that thermomemory involves metabolites that are generated during the priming phase with a role in conferring memory-based heat stress tolerance [3]. DNA methylation was also observed to increase during heat stress of Arabidopsis, oak, and rapeseed [3,5,6]. For instance, CHROMOMETHYLASE 2-dependent CHH methylation was suggested to act as an important alleviator of heat stress responses [7]. High accumulation of histone 3 lysine 4 methylation is associated with hyper-induction of gene expression upon recurring heat stress [4]. These studies show promising results because they suggest that plants actively use epigenetic mechanisms to adapt to stress. However, further research is required to understand how thermopriming can be used on a large-scale and not only in the lab to help the future of agriculture.

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References

1. Liu, J., L. Feng, J. Li, and Z. He. 2015. Genetic and epigenetic control of plant heat responses. Frontiers in plant science 6:267. https://doi.org/10.3389/fpls.2015.00267

2. Perilleux, C., A. Pieltain, G. Jacquemin, F. Bouche, N. Detry, M. D’Aloia, L. Thiry, P. Aljochim, M. Delansnay, A. Mathieu, S. Lutts, and P. Tocquin. 2013. A root chicory MADS-box sequence and the Arabidopsis flowering repressor FLC share common features that suggest conserved function in vernalization and de-vernalization responses. Plant Journal 75:390–402

3. Serrano, N., Y. Ling, A. Bahieldin, and M. M. Mahfouz. 2019. Thermopriming reprograms metabolic homeostasis to confer heat tolerance. Sci Rep 9:181. https://doi.org/10.1038/s41598-018-36484-z

4. Lämke, J., K. Brzezinka, S. Altmann, and I. Bäurle. 2016. A hit-and-run heat shock factor governs sustained histone methylation and transcriptional stress memory. EMBO J 35:162–175.

5. Naydenov, M., V. Baev, E. Apostolova, N. Gospodinova, G. Sablok, M. Gozmanova, and G. Yahubyan. 2015. High-temperature effect on genes engaged in DNA methylation and affected by DNA methylation in Arabidopsis. Plant Physiol Biochem 87:102-108.

6. Gao, G., J. Li, H. Li, F. Li, K. Xu, G. Yan, B. Chen, J. Qiao, and X. Wu. 2014. Comparison of the heat stress induced variations in DNA methylation between heat-tolerant and heat-sensitive rapeseed seedlings. Breed Sci 64:125-133.

7. Shen, X., J. De Jonge, S. Forsberg, M. Pettersson, Z. Sheng, Hennig L., and O. Carlborg. 2014. Natural CMT2 variation is associated with genome-wide methylation changes and temperature seasonality. PLoS Genet 10:e1004842. https:// 10.1371/journal.pgen.1004842