S11 - Session O3 - Epigenetic and physiological adaptative responses of apple seedlings to drought stress

Authors: Patricia Mallegol *, Amanda Cattani Malvessi, Sandrine Balzergue, Sylvain Hanteville, Jean-Marc Celton

The availability of water is one of the most threatening factors for crop production since it is related to plant development, productivity and survival. Apple fruit production is not an exception and environmental changes due to global warming, new precipitation patterns and increased frequency of extreme events are challenging producers all over the world. Recent studies have proposed that plant could quickly adapt their response to stress by modifying their epigenome, making epigenetic-based plasticity an interesting tool for breeders. In order to better understand the capacity of apple trees to adapt their morphological, transcriptomic and epigenetic response to drought (D), 162 seedlings from Golden Delicious Double Haploid (GDDH) were submitted to zero (control), one (Unique-D) or three cycles (Multiple-D) of 40% water-availability. Herein, one drought cycle includes 3 weeks of stress followed by 3 weeks of 100% water availability (recovery). Overall, we observed that plants from the Multiple-D group were smaller (-20%) compared to control group. Interestingly, young seedlings exposed to Unique-D showed a more vigorous and constant growth in comparison with non-stressed and Multiple-D plants. A larger stem diameter was also observed in Unique-D treatment when compared to other groups. While differences in node number were not observed between groups, shorter internodes length was noted in Multiple-D plants. Analysis of leaf anatomy revealed an increased mesophyll width in Multiple-D plants in comparison to control. Surprisingly, leaf anatomy of Unique-D plants was similar to Multiple-D plants even after the drought period, suggesting some adaptive mechanism and/or plant memory acquisition. The transcriptomic and epigenetic modifications in response to drought cycles are being investigated in order to understand molecular mechanism driving the drought-adaptive response of the perennial plant.