Drought Stress Priming Affects Tuber Yield and DNA Methylation Status in Vegetatively Propagated Potato (Solanum tuberosum L.) Plants

Drought stress is one of the major challenges for agriculture worldwide. The cultivated potato is a tetraploid tuber propagated crop that is sensitive to drought stress. We revealed that the tuber yield in two subsequent tuber progeny generations strongly depended on the cultivar and drought-induced memory. Upon non-stressed conditions, drought stress memory caused significant tuber yield losses in the first tuber progeny generation. In the second stress-free tuber generation, partial memory resetting was observed. DNA methylation has been shown to play a significant role in plant stress responses. Information on stress memory in crop plants is still limited. This is the first report on alterations in drought-induced DNA methylation levels in the long-term stress memory in potato. We showed that epigenetic changes induced by drought stress differentiated Katahdin and five Katahdin-derived potato cultivars (Cayuga, Dalila, Pontiac, Sebago and Seneca). We determined the cultivar-specific profiles of differentially methylated regions (DMRs) in the first tuber progeny generation of drought-primed and non-primed potato plants planted under non-stressed conditions. The epigenetic stress effects were transmitted to the first progeny generation and then largely lost in the subsequent generation. This suggests that other molecular components of the stress-inducible memory mechanism can affect the transmission of epigenetic information between two potato tuber generations. For cultivars ‘Cayuga’ and ‘Sebago’, primed plants produced lower tuber yields than non-primed plants in the first tuber progeny generation, and nine shared DMRs were localised on potato chromosomes. Four of them were attributed to genic regions, and two were cases of hypermethylation of proline-rich extensin-like receptor kinases.