The effect of DIMBOA concentration in leaf tissue at various plant growth stages on resistance to Asian corn borer in maize
1997
Tseng, C.T. (Corn Research center (China))
The chemical analytical values obtained for MBOA (6-methoxy-2- benzoxazolinone) were related to the labile cyclic hydroxamic acid precursors DIMBOA (2,4-dihydroxy-7-methoxy-(2H)-1 ,4-benzoxazin-3(4H)-one) which is formed enzymatically from its glucosides when the leaf tissues are crushed or placed at high temperature. The results of chemical analysis revealed that the A4BOA concentrations in leaf tissue decreased as the plants grew towards maturity, inversely the TLC plate ratings increased as the plants grew older. This showed that there were higher MBOA concentrations in the leaf tissue of earlier stage plants than in those of Later ones. Leaf-feeding damage ratings caused by artificial infestation with Asian corn borer (ACB), Ostrinia furnacalis (Guenee) egg masses and number of surviving borer larvae per plant increased as the plants grew older, indicating that younger plants were more resistant than older ones to corn borer feeding. Of 11 inbred lines tested JT 30-1-1-1-15-3 and C131A had lower leaf-feeding ratings, lower number of surviving larvae per plant and higher MBOA concentrations than any other lines at various stages of plant development. This implies that these 2 lines possess a remarkable degree of resistance to leaf-feeding by corn borer. The correlation coefficients of MBOA concentrations with leaf-feeding ratings at the 4th, 6th, 8th, 10th and 12th leaf stages were as follows: -0.85, -0.84, -0.86, -0.82, and -0.84 respectively, while the correlation coefficients of MBOA concentrations with number of surviving larvae at the same leaf stages in order were as follows:- 0.88, -0.83, -0.82, -0.78 and -0.80 respectively. The negative correlations of MBOA concentrations with leaf-feeding ratings and number of surviving borer larvae per plant were highly significant.
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