Recently, we reported that the novel
mitochondrial RNA editing factor SLO2 is essential for mitochondrial electron transport, and vital for plant growth through regulation of
carbon and energy metabolism. Here, we show that mutation in SLO2 causes
hypersensitivity to ABA and insensitivity to
ethylene, suggesting a link with stress responses. Indeed, slo2 mutants are hypersensitive to
salt and osmotic stress during the germination stage, while adult plants show increased drought and salt tolerance. Moreover, slo2 mutants are more susceptible to Botrytis cinerea
infection. An increased expression of nuclear-encoded stress-responsive genes, as well as mitochondrial-encoded
NAD genes of complex I and genes of the alternative respiratory pathway, was observed in slo2 mutants, further enhanced by ABA treatment. In addition, H2O2 accumulation and altered
amino acid levels were recorded in slo2 mutants. We conclude that SLO2 is required for plant sensitivity to ABA,
ethylene, biotic, and abiotic stress. Although two stress-related RNA editing factors were reported very recently, this study demonstrates a unique role of SLO2, and further supports a link between
mitochondrial RNA editing events and stress response.