Figure 1.

A scheme of stimulus-responsive isoprenoid biosynthesis in solanaceous plants. Sesquiterpene cyclase is a key branch enzyme of isoprenoid pathway for the synthesis of sesquiterpenoid phytoalexins. Vetispiradiene synthase, which catalyzes farnesyl diphosphate into vetispiradiene (1, 2, 3b), produces a precursor of lubimin and rishitin in potato and H. muticus. 5-epi-Aristolochene synthase is a key enzyme for capsidiol production in tobacco and pepper (1, 2, 3a). Wound-induced sterol and steroid glycoalkaloid syntheses are suppressed in favor of sesquiterpenoid phytoalexin synthesis during expression of the HR.