ARS | Publication request: Effect of chitinase and thaumatin on mycelial growth of five sorghum [Sorghum bicolor (L.) Moench] grain molding fungi under in vitro conditions

Submitted to: Journal of Tropical Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 16, 2011
Publication Date: November 1, 2011
Citation: Prom, L.K., Egilla, J. 2011. Effect of chitinase and thaumatin on mycelial growth of five sorghum [Sorghum bicolor (L.) Moench] grain molding fungi under in vitro conditions. Journal of Tropical Agriculture. 49(1-2):88-90.

Interpretive Summary: This study was conducted to determine the effect of certain chemical components, namely chitinase and thaumatin, on the growth of some fungal species that cause grain mold in sorghum. Compared with the control, four of the five fungal species had reduced growth when they were placed on half-strength potato dextrose medium containing either chitinase or a mixture of chitinase and thaumatin. One of the fungal species, Fusarium semitectum was more sensitive to the presence of thaumatin than chitinase. Both these chemical components are found in sorghum and other plants, and based on this study may play a part in reducing the growth of these grain molding fungi in the seed. Therefore, planting sorghum lines with high levels of these chemical components in their seeds, especially late in the season will help to reduce the effect of these grain molding fungi.

Technical Abstract: The effects of various concentrations of chitinase, thaumatin, and their mixtures on radial mycelial growth of five grain molding fungi were studied. When compared with the control, chitinase and mixtures of chitinase and thaumatin markedly reduced mycelial growth of all the fungal species, except for Fusarium semitectum. Reduction in fungal radial mycelial growth of 65.4% for Bipolaris sp. and 61.7% for Colletotrichum graminicola was noted when fungal species were grown on half-strength-potato dextrose agar amended with chitinase. A mixture of chitinase at 50 ml L-1 and thaumatin at 37.5 mg L-1 reduced mycelial growth of Bipolaris sp. by 61.7%, C. graminicola by 56.2%, and Curvularia lunata by 44.9% when compared with the control. The levels of thaumatin used in this study were less effective in inhibiting mycelial growth, except for F. semitectum. This study for the first time showed the suppression of mycelial growth in vitro of F. thapsinum, Bipolaris sp. and C. graminicola isolated from sorghum grain.