In W22 strains capable of producing anthocyanins in seedlings and leaf sheaths, Pl at first represses, but then later enhances anthocyanin in these tissues (MNL 48:153, 1974; MNL 49:154, 1975). We are currently comparing extracts of W22 Pl and pl seedlings by thin layer chromatography in order to determine the effects of Pl on other flavonoids. Our initial findings indicate that, at the two-leaf stage (when Pl is repressing anthocyanin accumulation), Pl reduces the concentration of flavonols in approximately the same proportion as it does the anthocyanins. Flavone concentrations, on the other hand, appear to be increased by the presence of the Pl factor. This latter finding surprised us because flavone concentrations in the seedlings are usually a good indication of the level of P locus activity (MNL 50:107, 1976). In that W22 P-WR bz seedlings have traces luteolinidin (a 3-deoxyanthocyanidin) glycosides, normally requiring P-RR if the seedlings are Bz, we thought it worthwhile to look at the effects of Pl on flavonoids in W22 bz seedlings also. So far we have found no 3-hydroxyanthocyanins in either Pl bz or pl bz seedlings, but flavonol glycosides are present in reduced amounts. Flavone concentrations again are higher in the Pl stocks, but the most noticeable effect of Pl is on the concentration of luteolinidin glycosides: whereas there are only trace amounts of these 3-deoxyanthocyanins in bz pl seedlings, there are measurable amounts in bz Pl seedlings. We should now be able to measure this effect of Pl quantitatively. We now intend to analyze P-WR bz stocks that have no anthocyanin-producing potential (e.g., r-g b) and also P-WW bz stocks that have no P locus activity. Hopefully we should then be able to tell if Pl is stimulating the production of luteolinidin via the 3-hydroxyanthocyanin pathway, or whether Pl can stimulate the production of flavonoids controlled by the P locus even when the normal anthocyanin pathway is blocked.
E. Derek Styles and Oldriska Ceska
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