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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.

Two tomato inbreds (one advanced greenhouse line, P1=Ohio ICR.9 and one frost resistant line, P2=Ohio 4013-3) and F1, BC1, BC2 and F2 progeny were examined for growth and development during December and January to determine inheritance of biomass characters. Two-week-old seedlings from each generation (8 from the P1, P2 and F1; 32 from the BC1 and BC2; and 64 from the F2) developed over a 9-week period at 2 different night temperatures (17 and 12 C) and light levels (natural light and 30% shade, 5 days/week). The F1 generation had the highest leaf area and total dry weight means followed by the BC1 and P1 generations. The variance components for leaf area and total dry weight accumulation were: Ve = 120,300 and 2.63; Vp = 553,618 and 12.46; Va = 127,475 and 3.65; and Vd = 305,843 and 6.18, respectively. Both traits are highly heritable, having a broad sense heritability of 0.78 and 0.79 for leaf area and total dry weight, respectively. However, because narrow sense heritability is low, 0.23 and 0.30, respectively, improvement in biomass accumulation will be more difficult.