Lysine biosynthesis impairment shapes heat-stress acclimation through metabolic and transcriptional reprogramming in Arabidopsis thaliana
Global warming is increasing the frequency and intensity of high-temperature episodes, limiting plant productivity. However, the molecular mechanisms integrating primary metabolism with the heat stress response remains poorly understood. Here, we show that lysine biosynthesis contributes to the coordination of physiological, metabolic and transcriptional responses to heat stress in Arabidopsis…
In a study examining the impact of heat stress on Arabidopsis thaliana, researchers found that the impairment of lysine biosynthesis plays a crucial role in shaping the plant's acclimation to high temperatures. The researchers compared wild-type plants to mutants with disrupted lysine biosynthesis, as well as mutants affected by salicylic acid (SA) biosynthesis and signaling.
These comparisons were made under prolonged warming (6°C above normal for 7 days) and heat shock (38°C for 6 hours), with observations taken both before and after recovery.
The researchers noted that the lysine-biosynthesis mutant, designated as "dapat," exhibited a unique metabolic state prior to heat stress. This state was characterized by increased amino acid accumulation, altered organic acid profiles, reduced soluble sugars, and elevated endogenous SA levels. These changes were maintained throughout the prolonged warming period, while wild-type plants and SA-pathway mutants underwent more dynamic reprogramming.
When subjected to heat shock, the response was more convergent across all genotypes. However, the study revealed that despite reduced photosystem II (PSII) efficiency, the "dapat" mutant maintained its photosynthetic performance during prolonged warming and recovered effectively. In contrast, wild-type plants and SA-pathway mutants experienced a more pronounced response to heat shock.
Interestingly, the transcriptional response to heat stress differed significantly between the genotypes. While "dapat" showed either constitutive or stronger expression of selected heat-responsive genes, some canonical heat-stress regulators displayed weaker induction after heat shock. Additionally, RNA sequencing revealed a largely conserved core heat-shock response among all genotypes. However, the regulation of defense, hormone, and amino acid metabolism programs was genotype-dependent, particularly during recovery.
In conclusion, the findings of this study suggest that impaired lysine biosynthesis establishes a metabolically primed but energetically constrained state in Arabidopsis thaliana. This state affects gas exchange, photosynthetic acclimation, and heat-responsive transcription. The research highlights lysine homeostasis as a critical regulatory node linking primary metabolism and SA accumulation, demonstrating its integration with both SA-dependent and SA-independent components of heat-stress acclimation.
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