Genetic Variation for Maysin and Its Analogues in Crosses among Corn Inbreds
1998
Widstrom, N. W. | Snook, M. E.
The isolation and identification of maysin and two of its analogues, 3′-methoxymaysin and apimaysin (3′M+A), in the silks of corn, Zea mays L., has given plant breeders a new tool for reducing damage by larvae of the corn earworm, Helicoverpa zea (Boddie). This study was initiated to examine the inheritance of these compounds so that a logical course for developing germplasm with high concentrations can be determined. Incorporation of the compounds into corn hybrids for the southern USA can then proceed. Twelve inbred lines were crossed in all combinations and evaluated for maysin and the sum of 3′-methoxymaysin plus apimaysin concentrations in their silks. Analysis of data from 2 yr by Griffing's Method 3 Model I revealed that reciprocal and maternal effects were not significantly different from zero. Subsequent pooling of reciprocal crosses in a Gardner-Eberhart Analysis II gave significant main effects (P < 0.01) and years ✕ entries interactions (P < 0.05). Further partitioning of the variation established additive effects as the predominant source of genetic variation among the 66 crosses evaluated. Selection for increased maysin and (3′-methoxymaysin plus apimaysin) concentrations in corn silks should be successful by means of a simple backcrossing procedure or routine recurrent selection within a population. One or two inbreds, among the 12 tested, appear to be good candidates for establishing a selection program because they have both good general and specific combining ability. Maysin concentration and the sum of its analogues 3′-methoxymaysin and apimaysin are closely correlated in corn silks (r = 0.81, P < 0.01).
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