leaf epidermal cells are biosynthetically competent to produce secologanin precursors that are converted via many enzymatic transformations to make 16-methoxytabersonine, which is then transported to cells within Catharanthus leaves to complete the last three or four enzymatic transformations to make vindoline
the enzyme is important in the monoterpenoid indole alkaloid (MIA) biosynthesis in Catharanthus roseus, subcellular organization of the central steps of the pathway, overview. The ring-opening reaction of loganin in the biosynthesis of secologanin is catalyzed by the fourth P450 of this pathway, secologanin synthase (SLS, CYP72A1). Both isozymes SLS1 and SLS2 not only catalyze the oxidative ring cleavage of loganin to produce secologanin but also perform the oxidation of secologanin into secoxyloganin. SLS1 and SLS2 constitute the third type of P450 from the seco-iridoid pathway performing more than one catalytic reaction. Additional enzymes might convert secoxyloganin back to secologanin, the subcellular compartmentation of secologanin biosynthesis may also limit secoxyloganin formation in planta. Secoxyloganin is an acidic compound derived from secologanin that is no longer able to be condensed with tryptamine by STR in the vacuole, due to the absence of the aldehyde function. If secoxyloganin formation occurs in vivo, the resulting depletion of the secologanin pool is deleterious for the subsequent synthesis of MIAs
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significant upregulation in salicylic acid treatment (foliar application of 0.01 and 0.1 mM salicylic acid). Upregulation can result in a higher production rate of vinblastine and vincristine alkaloids
localization of tabersonine 16-hydroxylase and 16-OH tabersonine-16-O-methyltransferase to leaf epidermal cells defines them as a major site of precursor biosynthesis in the vindoline pathway in Catharanthus roseus