Steroidal glycoalkaloids in Solanum chacoense have been found to deter feeding by herbivores, especially to Colorado potato beetle. The steroidal glycoalkaloids of S. chacoense include solanine (chaconine), leptinines, and leptines, which yield solanidine, leptinidine, and acetylleptinidine, respectively, upon acid hydrolysis. To understand the regulation of their biosynthesis, tissue culture plants were grown on MS media containing jasmonic acid, methyl jasmonate, or arachidonic acid at different levels. After 1 month in culture, 100 μM jasmonic acid stimulated solanidine, leptinidine, and acetylleptinidine accumulation 3- to 10-fold compared to control. Methyl jasmonate at 100 μM also induced solanidine accumulation, but not leptinidine and acetylleptinidine. Arachidonic acid had no effect on solanidine, leptinidine, and acetylletptinidine levels. Furthermore, leptinidine and acetylleptinidine levels increased 5-fold and 100-fold, respectively, after plants were transferred from culture in vitro to soil; meanwhile, solanidine level decreased slightly. Solanidine, leptinidine and acetylleptinidine from plants in vitro showed no changes during the same period. Our results indicated that jasmonic acid and environmental factors play important roles in the biosynthesis of steroidal glycoalkaloids in S. chacoense.
A Dioxygenase Catalyzes Steroid 16α-Hydroxylation in Steroidal Glycoalkaloid Biosynthesis
