Flavonoids in maize pollen

We have made a broad survey of the flavonoids found in maize pollen and tested genotypes varying at the following loci (parentheses indicate the number of different alleles tested at each locus): A(5); A2(2); A3(2); B(2); Bz(2); Bz2(2); C(2); C2(3); In(2); P(4); Pl(2); Pr(2); R(6); and Sm(2). Pollen was-extracted in methanol as so-me glycosides were unstable in acidified methanol. Duplicate extractions were made for genotypes with red or brown pollen, one in methanol and one in acidified methanol. The following is a summary of our findings to this point:

1) There were no flavones in any of the extracts.

2) Several Pl stocks had anthocyanins in the pollen, including some R-r B Pl lines, and most R-ch and r-ch Pl lines. The 'Chocolate pollen' of A. Tavcar (MGCNL 24:67) and the 'Pink pollen' of R. Brawn (MGCNL 29:33) were from purple anthered Pl stocks.

3) There were at least six pollen specific flavonol glycosides in most of the samples, and small amounts of quercetin 3-glucoside, the most common flavonol found in plant tissues. Some of the pollen specific flavonols are based on quercetin, others on isorhamnetin. Except for the compounds found in bz stocks (see below), all are glycosylated at the 3-position, and all are at least diglycosides.

4) In bz stocks, the concentrations of 3-glycosylated flavonols are markedly reduced, and they are replaced by at least three other glycosides that have the 3-hydroxyl free, and some aglycones. Bz/bz plants have normal amounts of the 3-glycosylated flavonols, and no flavonols with the 3-hydroxyl group free.

5) C2-Idf causes a marked reduction, but not a complete inhibition, of all flavonoids in both Bz and bz pollens. C2/C2-Idf plants have about 50% of the concentrations found in C2 C2.

6) Variations at the other loci had little if any qualitative or quantitative effects on the pollen glycoside patterns.

E. D. Styles and O. Ceska

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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