ERGOSTEROL CONCENTRATION IN MOLD-SUSCEPTIBLE AND MOLD-RESISTANT SORGHUM AT DIFFERENT STAGES OF GRAIN DEVELOPMENT AND ITS RELATIONSHIP TO FLAVAN-4-OLS

Sorghum [Sorghum bicolor (L.) Moench] germplasm and breeding lines exhibiting contrasting reactions to the grain mold complex were grown at Patancheru, India. Grains were harvested at different days after flowering (DAF) and analyzed for ergosterol. Methanol and acidified methanol extracts of grains were analyzed for flavan-4-ols. Ergosterol concentration increased with increasing DAF in the mold-susceptible accessions and was 10-fold higher in grains collected at 50 DAF than in the corresponding mold-resistant accessions. Ergosterol concentration could therefore be used to assess the magnitude of mold damage in sorghum grains. The correlation coefficient between ergosterol and flavan-4-ols concentrations was significant (P < 0.01) and negative in colored mold-susceptible and mold-resistant accessions that did not have testa, but no significant correlation was observed in white mold-resistant and mold-susceptible sorghum. This indicates that there must be another genetic trait or mechanism besides flavan-4-ols that is associated with mold resistance.