LEVELS OF MAYSIN AND MAYSIN ANALOGS IN SILKS OF MAIZE GERMPLASM

Maysin mnosyl-6-C-(6-deoxy-xylo-hexos-4-ulosyl)luteolin], the resistan ce factor of Zapalote Chico corn (Zea mays L.) silks to the corn earwo rm (Helicoverpa zea Boddie), was determined by HPLC in the silks of ov er 600 inbreds, populations, plant introductions (PI), and various una ssigned collections. Maysin levels ranged from 0% to 0.9% fresh weight with approximately 19% of both the inbreds and populations containing maysin levels above 0.2%, a level considered to be necessary for resi stance, as based on the laboratory bioassay determined level (for larv al) of maysin toxicity. Over 25 lines-yielded higher silk maysin than found in Zapalote Chico (0.347%). High levels of hamnosyl-6-C-(6-deoxy -xylo-hexos-4-ulosyl)apigenin (apimaysin) were found in inbred NC7, wh ile Tx501 contained appreciable amounts of C-(6-deoxy-xylo-hexos-4-ulo syl)-3'-methoxyluteolin (3'-methoxymaysin). Spectral data (C-13 NMR an d FAB-MS) are given for the characterization of maysin, apimaysin, and 3'-methoxymaysin.