Morphological and biochemical characterization of thermotolerant trichoderma

The study focuses on the morphological and physiological cell responses to high temperature stress in thermotolerant isolates of Trichoderma viz., T. longirachiatum 673 (TaDOR673) and T. asperellum 7316 (TaDOR7316). Heat shock of 52 °C led to changes in morphological characteristic viz., decrease in the size and volume of spores but the reduction was significantly less in comparison to susceptible Trichoderma isolates tested. Scanning and transmission electron microscopy (TEM) of fungal cultures heated at 52 °C demonstrated shrinkage of cytoplasm and reduced intracellular spaces and mitochondrial count. The observations have supported the hypothesis of reduced metabolism during stress conditions. TEM analysis also revealed increased accumulation of vacuoles indicating their role as scavengers of toxic metabolites generated during heat stress. The isolates showed different patterns of lytic enzyme production and we observed that the thermotolerant isolate T. asperellum TaDOR7316 was able to produce β-1, 4-glucanases even after heat stress and thus it can be further tested for biological control of plant pathogens under stress conditions