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ARS Home » Southeast Area » Tifton, Georgia » Crop Genetics and Breeding Research » Research » Publications at this Location » Publication #82090
Title: A GENE CONTROLLING BIOSYNTHESIS OF ISOORIENTIN, A COMPOUND IN CORN SILKS ANTIBIOTIC TO THE CORN EARWORM

Author
item Widstrom, Neil
item SNOOK, M. - UNIVERSITY OF GEORGIA

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The larvae of the corn earworm is an important pest of corn, sometimes causing severe ear damage to field and sweet corn hybrids. The chemical isoorientin is present in silks of some corns at a concentration that is harmful to the corn earworm. T218 is a corn line that produces biologically active levels of this compound. It was evaluated in hybrid combination with two other non-isoorientin producing lines to determine inheritance of isoorientin in corn silks. Silks from parents, crosses, and segregating generations were evaluated in 1994 and 1995 for isoorientin concentration. Liquid chromatography was used to make chemical determinations. Segregation ratios in the segregating generations were tested using statistical procedures. The tests were conclusive in the identification of one recessive gene influencing high isoorientin concentration in the silks of inbred T218. Some evidence for other minor genes existed, but the major portion of isoorientin was conditioned by the one recessive gene. Development of inbreds with high concentrations of isoorientin in their silks will add to the arsenal of other compounds in corn silks to combat damage to corn by corn earworm larvae.

Technical Abstract: The corn earworm (Helicoverpa zea, Boddie) is an important pest of corn (Zea mays, L.), its larva sometimes causing severe ear damage to hybrids grown in the southeastern United States. The antibiotic compound isoorientin is present in silks of somecorn inbreds at concentration that is harmful to the corn earworm larva. T218 which produces biologically active levels of this compound was evaluated in hybrid combination with two other non-isoorientin producing inbreds to determine the mode of isoorientin inheritance in corn silks. Silk masses from individual ears of each parent, the F1, F2, first backcrosses, F3 families and selfed BC1 families were evaluated in 1994 and 1995 for isoorientin concentration. Liquid chromatography (HPLC) was used to make chemical determinations. Segregation ratios in the F2, first backcross to the high parent, F3 families and selfed BC1 families were tested using Chi-square techniques. The tests were conclusive in the identification of a single recessive gene controlling high isoorientin concentration in the silks of inbred T218. Some evidence for modifiers existed, in that there was a statistically nonsignificant trend for more plants than expected to occur in the low isoorientin concentration classes. Development of inbreds with a high concentration of the simply inherited isoorientin in their silks will add to the arsenal of compounds available in corn silks to combat damage to corn by corn earworm larvae.