Properties and biological control activities of aerial and submerged spores in Trichoderma asperellum SKT-1

Abstract

Trichoderma asperellum SKT-1, a biocontrol agent that is highly effective against rice seedborne diseases, forms submerged spores by liquid culture. These submerged spores had some common properties with aerial spores, but differed in surface topology and internal organization. Aerial spores, so called conidia, maintained high viability under dry storage conditions, whereas the viability of submerged spores was reduced. The cell wall of submerged spores was thinner than that of aerial spores, and the surface was smooth in contrast to the irregular pyramidal warts of aerial spores. Both submerged and aerial spores were highly effective against “Bakanae” disease by seed-treatment. Therefore, these two-types of spores were suitable for different applications.