Overexpression of the apple m⁶A demethylase gene MdALKBH1A regulates resistance to heat stress and fixed-carbon starvation

The pivotal role of N⁶-methyladenosine (m⁶A) demethylases in regulating plant stress responses has been widely explored; however, the function of apple m⁶A demethylases under heat stress and fixed-carbon starvation is unclear. In this study, the apple RNA demethylase gene family was identified, and the demethylase gene MdALKBH1A was selected for further analysis. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, we demonstrated that MdALKBH1A is the m⁶A demethylase of apple. Moreover, transgenic ‘Micro Tom’ tomato plants overexpressing MdALKBH1A were more sensitive to high temperature, probably due to the decreased antioxidant ability, increased membrane lipid peroxidation and reduced plasma membrane stability. However, these tomato plants overexpressing MdALKBH1A were more resistant to fixed-carbon starvation, as evidenced by the improved plasma membrane stability, enhanced photosynthetic rates and elevated autophagic activity. In summary, our results highlight the crucial role played by MdALKBH1A in the response of apple plants to high-temperature stress and fixed-carbon starvation.