Drought stress from relative humidity control induces nutrient starvation stress
Description
Autophagy contributes to the maintenance of life by degrading and removing proteins and organelles damaged by various environmental stresses. Autophagy-deficient (atg) mutants are known to be sensitive to environmental stresses, such as oxidative stress. In Physcomitrium, atg mutants exhibit greater sensitivity to nutrient starvation (carbon, nitrogen, and phosphate) compared to wild-type (WT). Furthermore, when Physcomitrium is incubated in the dark, chlorophyll is degraded, leading to decolorization, indicating that atg mutants are sensitive not only to nutrient starvation but also to darkness. In this study, we focused on drought stress, which plants frequently experience in their natural environment, and examined the response of atg mutants in Physcomitrium under drought stress conditions of 13% relative humidity (RH) using LiCl and 43% RH using K₂CO₃. Immediately after exposure to drought stress, both WT and atg mutants retained their green color under 13% RH; however, atg mutants faded under 43% RH. This difference may be attributed to reduced intracellular metabolic activity and suppressed chlorophyll degradation under 13% RH, whereas chlorophyll degradation was enhanced under 43% RH. These findings suggest that nutrient starvation stress should be considered even under mild drought conditions, such as 43% RH.
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Institutions
- Saitama Daigaku