Physiological and molecular insights into drought-induced memory in potato leaves

Photosynthesis is the main determinant of crop yield. Drought is reported to be one of the major abiotic stresses that negatively affect photosynthetic capacity. Water deficit reduces net leaf assimilation and carbon export from source to sink organs. Potato ( Solanum tuberosum L.) tubers are strong sink organs. Modern potato cultivars are considered sensitive to drought. Two potato cultivars, Cayuga and Dalila, were studied. In Cayuga plants, the first tuber generation of primed plants had significantly lower tuber yield than non-primed plants. In Dalila plants, the differences in tuber yield were not statistically significant. Here, we provide the first report on the effect of drought-induced memory on photosynthetic activity in potato plants grown under non-stressed conditions. In Dalila plants, fourteen JIP -test parameters were significantly altered in drought-primed Dalila plants, as compared to the control, of which PI _inst , PI _ABS and DF _ABS showed the highest values. In Cayuga plants, the observed changes in JIP-test parameters were not significant. Gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment for differentially expressed genes (DEGs) in Dalila plants showed that photosynthesis-related pathways may be essential in response to drought-induced memory. The top three categories included ‘photosynthesis, light harvesting in photosystem I’, ‘response to light stimulus’ and ‘photosynthesis-antenna proteins’. In contrast, only a few DEGs were observed in the progeny of primed vs. non-primed Cayuga plants. We have shown that the maintenance or fading of drought-induced memory involves processes related to photosystem activity, which may result in the observed variation in potato tuber productivity under non-stressed conditions.