|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1995 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1994 : ¥1,800,000 (Direct Cost : ¥1,800,000)
1. Production of biocontrol agents by transfer of a chitinolytic enzyme gene
Marine bacterium, Alteromonas sp.strain 79401 was shown to suppress the condial growth of plant pathogenic fungi. Botrytis cinerea and Botrytis fabae in vitro by meane of its high chitinolytic activity. To use the ability of this bacterium for biocontrol, a DNA fragment (ca.3.5kb) carrying the chitinolytic enzyme gene was cloned into the plasmid p22-k2. The resulting plasmid, chia-p22-k2/L2 (a9) was introduced into Erwinia ananas L2.B.cineres, B.fabae, Colletotrichum cyclamenae and Rhizoctonia solani could not grow in the vicinity of the transformed E.ananas colonies in vitra Conidial germination and hyphal growth were markedly suppressed. Swelling of the conidia and germ tubes and bursting of hyphal tips were observed under a microscope, suggesting that tha chitinolytic enzyme affected the fungal cell walls. This a9 isolate might be useful for the biocontrol agent of plant pathogenic fungi.
2. Biocontrol of cyclamen diseases by Serratia marcescens B2
In biocontrol testing, cyclamen plants were applied with a highly chitinolytic bacterium, Serratia marcescens isolate B2 and after 24 h, challenge-inoculated with conidia of Botrytis cinerea and Colletotrichum cyclamenae, respectively. The isolate B2 suppressed the fungal disease incidences by ca.60% on attached petals and leaves of cyclamen in a greenhouse. The efficacy of isolate B2 against these fungi was nearly equal to that with 200ppm of iprodione. Although the isolate B2 failed to survive on the petals and leaves more than 2 weeks after the application, the populations on the leaf-bud and the petioles near the base of the cyclamen plant, on which the gray mold and the anthracnose regularly developed, increased 10-fold during this period. These results suggest that S.marcescens B2 is a a potential biocontrol agent against cyclamen fungal diseases under greenhause conditions.