Nine hundred and seventy-six bacterial isolates were obtained in this study, among which a bacterial antagonistic isolate, Bacillus subtilis S9 from sugarcane rhizosphere showed cell-lytic effect on the plant pathogens, Rhizoctonia solani, Pythium ultimum and Fusarium oxysporum f. sp. niveum after 4-day-confronting incubation on PDA plates. However, S9 could not cause obvious inhibitory zones on PDA plates during this incubation. Lytic spots of hyphae of R. solani caused by S9 were clearly presented under scanning electronic microscope. The cell-lytic process of S9 is as follows: Bacterial cells of S9 absorb on hypae of R. solani firstly, and grow and reproduce as the fungal hyphae grow, and then secrete some cell-lytic substances to decompose the hyphae. However, this study revealed that S9 hardly interfered with the growth of the fungal antagonists, such as Trichoderma viride, Chaetomium cupreum and Chaetomium globosum. Pot experiments proved that S9 could effectively control root disease of tomato caused by R. solani. It Suggested that S9 mixed with above fungal antagonists could potentially synergistically control plant diseases caused by pathogenic fungi.

We have constructed a fungal subtractive suppressive library enriched in genes expressed during appressorium maturation in Magnaporthe grisea. Sequencing of 250 clones from the subtracted appressorium cDNA library revealed 142 unique genes, represented by 155 non-redundant ESTs (expressed sequence tags). Of these ESTs, 72 have not been previously isolated in M. grisea. RTPCR analysis of 105 of the genes discovered found transcripts corresponding to 71 of the ESTs only in mature appressoria while transcripts corresponding to a further 34 of the isolated ESTs were expressed both in appressoria and condia/mycelia. Genes specifically expressed in appressorium identified by SSH included a number that have been previously implicated in appressorium formation or function including GAS1, GAS3, and PTH11.

Conidium germination and approssorium formation rate under eight subatratea, different agar surface with various cAMP and IBMX concentration gradients, different nutrient resource, pH value of conidial suspensison, and cultural filter of antigonistic bacteria were observed. Conidium density of its suspeusion and its pH value did not affect the appressorium formation of Magnaporthe grisea 91-11B1, high density (conidia>10 5/mL) and unsuitable pH value (>10 or <4) would significantly reduce the germination of conidia The hydrophobic substratum surfaces could enhance the appressorium formation, The starvation of nutrition and the surfaces of onion epidermis could stimulate the appressorium morphogenesis, and rich mltrition could inhlbh it, Compared with ion-free pure water,tap water could facilitate the appressorium formation, 2.5mmol/L cAMP and 8.0mmol/L IBMX, the mostly commonly used phosphodiesterase inhibitor, significantly promote apressorium formation. Conidia which collected by vibrating method were more elfective to differentiate into appressorium than those by washing method. Among 13 strains of antagonistic bacteria, three sttains, such as Xb216, Xh240 and Xh220 strongly iuhibited the germination and appressorium formation.

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