The Parasitism Of Gliocladium Roseum 67-1 Strain On Sclerotia Of Sclerotinia Sclerotiorum And The Molecular Mechanism Involved

Gliocladium species were a group of fungi inhabited widely and commonly in the soil and were important biocontrol agents against crop pathogenic fungi. The 67-1 strain of G roseum (GR67-1) was isolated from the soil collected from Hainan Province, China. Previous studies indicated that this fungus was a strong parasite and pathogen of many plant pathogens. In the present study, the effects of GR67-1 on Sclerotinia sclerotiorum and the molecular mechanism involved in the antagonism were investigated.Dual culture of S. sclerotiorum and GR67-1 strain on PDA plates showed that GR67-1 inhibited mycelium and colony growth of S. sclerotiorum significantly. The sclerotia of S. sclerotiorum were treated for 30 min in GR67-1 spore suspension (10~8 spores/ml) and then wet-cultured on saturated filter papers in petri dishes. These treated sclerotia were completed rottened in seven days. There were no germinations when the rottened sclerotia were cultivated on PDA at 25°C for 4-7 days; only the growth and sporulation of GR67-1 was prosperous. These results indicate that most significant antagonistic effect of GR67-1 against S. sclerotiorum is to inactivate the sclerotia and also to suppress hyphal growth of the plant pathogen.After the sclerotia were soaked for 30 min in GR67-1 spore suspension (10~8 spores/ml) and then wet-cultured on saturated filter papers in petri dishes, the activity of several common cell-wall degradation enzymes in the grounded sclerotia liquid was determined during the culturing period. The activity of glucanase was strong and reached the highest on the 7th day following antagonistic treatment. The activity of chitinase, cellulase and protease were extremely weak or not detectable all the time. It is...