Relationship between jasmonic acid accumulation and senescence in drought-stress

Plants raised from shoot-tip cultures of apricot (DT: drought-tolerant genotype Prunus armeniaca L. cv. Ansu Maxim, and DS: drought-sensitive genotype P. armeniaca L. cv. Longwangmao) were grown in pots of peat-based compost. Water was withheld for 12 days. Gas chromatography-mass spectrometry analysis indicated that jasmonic acid (JA) levels in leaves of DT plants increased three-fold on day 12 after water was withheld, while there was little variation in leaf JA in DS plants for the whole drying period. There was no significant difference in the JA concentration in roots of the two apricot cultivars from 1 - 9 days. JA concentration in DT plants roots increased slightly by 12 days compared to JA concentration in DS. There was 100% abscission in DT plants at 13 days, earlier than 14 days for DS. Two months after rewatering, 12 of the 18 DT plants were alive, but all 18 DS plants were dead. Exogenous JA accelerated leaf senescence in both DT and DS plants by chlorophyll loss. After JA treatment there were increased malondialdehyde (MDA) levels in DT and DS plants. These results suggest that the transient JA accumulation from DT leaves may promote leaf senescence due to soil drying, thus avoiding excessive water loss, and aiding drought survival.