Analysis of Trichoderma harzianum TR 274 secretome to assign candidate proteins involved in symbiotic interactions with Phaseolus vulgaris

Trichoderma spp can colonize host plants protecting them from pathogen infection. This association is accomplished by an exchange of molecules secreted by both the host plant and symbiotic fungus. In the present work, using LC-MS/MS analysis, our research group described a list of proteins secreted by T. harzianum TR274 during association with common bean (Phaseolus vulgaris). The main goal is to describe candidate proteins critical for the formerly mentioned association and understand mechanisms related to hosting plant tissue's colonization and modulation of bean plant defense response or metabolism. T. harzianum TR 274 could colonize common bean roots, increasing the transcript levels of defense-related genes (chit, glu1, and pal). Secretomes were obtained from culture filtrates harvested after the growth of T. harzianum TR 274 in the presence (Secretome of co-cultivation-SCC) or absence (Secretome of fungus condition-SFC) of the host plant. We identified 124 and 190 fungal proteins in SCC and SFC, respectively. A total of 30 proteins were detected only in SCC, and 94 were detected in both secretomes (SCC and SFC). The host plant presence decreases the number and diversity of proteins secreted by T. harzianum. The main functional categories represented are glycoside hydrolases, proteases, oxidoreductases, and SSCPs (Small soluble cysteine-rich secreted proteins). Our results provide a list of protein candidates for functional gene studies and validate their role in interactions between T. harzianum and P. vulgaris. Therefore, it contributes to understanding the main mechanisms of T. harzianum host plant colonization and the modulation of defense response.

Automated summary

Using LC-MS/MS analysis, this study identified and described the proteins secreted by T. harzianum TR274 during its association with common bean. The presence of the host plant affected the number and diversity of proteins secreted by T. harzianum. The identified proteins were mainly glycoside hydrolases, proteases, oxidoreductases, and small soluble cysteine-rich secreted proteins.