イオンビームによる内生細菌の改良及びオリゴキトサン施用による内生細菌の効果増強

Improvement of endophytic bacteria using ion beams and application of bio-pesticide with plant growth promoter made from oligo-chitosan

相野 公孝*; 佐藤 勝也; 長澤 尚胤; 田口 光正; 鳴海 一成*

Aino, Masataka*; Sato, Katsuya; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Narumi, Issey*

生物農薬の原体微生物 FPH9601菌株を用いて、イオンビーム突然変異育種のための最適線量を求めたところ、300Gyの照射線量において最も変異株の出現率が多いことが判明した。今回は、検定数を増やし変異株の選抜を行った。一方、植物に生理活性を有するオリゴキトサンを用いて、 FPH9601菌株のトマト青枯病発病抑制効果の増強が可能かどうかを検討した結果、ポット試験において、高い増強効果が認めた。今回は、圃場条件においてもその併用効果が得られるかどうかを検討した。その結果、内生細菌に感染したトマトを定植後、地上部へのオリゴキトサンを散布することにより内生細菌の効果増強が確認されたが、圃場の青枯病菌の汚染程度が高くなるに従ってその効果が低くなった。

The endophytic bacteria produce various kinds of bioactive substances, by which the plants grow well and exhibit resistance to diseases and environmental stress. In this study, 300 isolates that were derived from FPH9601 irradiated with carbon ion beams were tested for inhibitory effect of tomato bacterial wilt. We could successfully obtain 24 mutants that have enhanced suppressiveness against the tomato bacterial wilt. In the meantime, chitosan is a linear polysaccharide composed of randomly distributed -(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Low molecular weight chitosan (oligo-chitosan), which can be obtained by -ray irradiation of chitosan in diluted solutions, has potential uses in agriculture. In the field condition, the suppression effect against the pathogen significantly increased when tomato was treated with oligo-chitosan and endophytic bacteria.