Identification of a highly drought-resistant pp7l hda6 mutant

Plants have evolved efficient strategies to cope with drought stress, including stomata closure, significant changes in nuclear gene expression, and epigenetic mechanisms. Previously, we identified Arabidopsis thaliana PROTEIN PHOSPHATASE7-LIKE (PP7L) as an extrachloroplastic protein that promotes chloroplast development and high light, and salt tolerance. Here, we demonstrate that the pp7l mutant can withstand prolonged periods of drought stress. Interestingly, chloroplast development in pp7l recovers under drought conditions, despite growth of the mutant is impaired under normal growth conditions. To assess the (post)transcriptional changes occurring in the pp7l mutant under different durations of drought exposure, we used long non-coding RNA-sequencing. Compared to the previously reported drought-responsive changes in the wild type, the drought-responsive changes detected in the pp7l mutant were negligible. Our analysis of data generated in this study and previously motivated us to create a pp7l hda6 mutant, which exhibits remarkable drought resistance. Notably, the growth penalty associated with pp7l was alleviated in the double mutant, ruling out a dwarf effect on the drought-tolerant trait of this genotype.