Effects of Jasmonates on in vitro Tuberization in Several Potato Cultivars that Differ Greatly in Maturity

Abstract

Late-maturing cultivars of potato form tubers much later than early-maturing cultivars in a field. Jasmonic acid (JA) induced in vitro tuberization in various cultivars that differed greatly in maturing time. Airborne JA-Me was also able to induce tuberization in all the cultivars tested. However, the early- or late-maturing habit (maturity) affected largely their tuberizing response to JA; the later the maturing time of the cultivar, the lower the response. The etiolated shoots developed from the tubers of late-maturing cultivars had longer internodes than the early-maturing cultivars, suggesting that the levels of endogenous gibberellins (GA) in them are higher in the former than in the latter. Since gibberellic acid strongly inhibited JA-induced tuberization, the lower tuberizing response of late-maturing cultivars to JA may be attributable to high levels of endogenous GA. An exceptional result was obtained in an extremely late-maturing cultivar, which had a medium length of internodes but showed high tuberization in response to JA. These results suggest that not only GA but also jasmonates are the key factors determining maturity; either a higher level of GA or a lower level of jasmonates may predispose the cultivars to have a late-maturing habit.