Enzymatic functions and mycoparasitism vs sclerotia in Trichoderma

The mycoparasitic activity of Trichoderma spp. against sclerotial phytopathogenic fungi is a powerful tool for a biocontrol agent, since these highly resistant vegetative structures represent the pathogen primary survival form in soil. Parasitic interactions established by Trichoderma against sclerotial fungi have been mainly investigated by histological and biochemical analysis. Several enzymatic activities have been related to sclerotia mycoparasitism, such as enzymes degrading cell wall components (chitinase, cellulase) or phenolic compounds (laccase, lignin and melanin degrading enzymes), protease and lipase. The availability of a T. virens isolate (I10) transformed with genes coding for fluorescent proteins, red (I10DsRed) and green (I10GFP), allowed to monitor Trichoderma as antagonist in natural environments (1) and to follow in vitro sclerotia colonisation of Sclerotium rolfsii and Sclerotinia sclerotiorum (2). The present work aims to identify enzymatic activities related to the mycoparasitic ability by a genetic approach. Mutants of I10DsRed and I10GFP were selected for specific functions in order to evaluate their sclerotia colonisation ability. S. sclerotiorum and Botrytis cinerea were used as phytopathogenic sclerotia producing fungi. Mutants were screened for cellulases, chitinases, lipases, proteases and laccases activities; the correlation between defective traits and sclerotia colonisation is under investigation. REFERENCES 1. Mikkelsen L, Sarrocco S, L\ufcbeck M and Jensen DF. FEMS Microbiology Letters 223: 135-139 (2003). 2. Sarrocco S, Mikkelsen L, Vergara M, Jensen DFM, L\ufcbeck M and Vannacci G. Mycological Research 110: 179-187 (2006)