L-form bacteria of Pseudomonas syringae pv. phaseolicola induce chitinases and enhance resistance to Botrytis cinerea infection in Chinese cabbage

• Published in: Physiological and molecular plant pathology 2003-05, Vol.62 (5), p.253-263
• Main Authors: Daulagala, P.W.H.K.P, Allan, E.J
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biological control; Botrytis cinerea Pers; Brassica campestris L. ssp. pekinensis; Chitinase; Control; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Induced resistance; L-form bacteria; Phytopathology. Animal pests. Plant and forest protection; Plant association; Pseudomonas syringae pv. phaseolicola; Symbioses
• ISSN: 0885-5765; 1096-1178
• DOI: 10.1016/S0885-5765(03)00089-4

Induction of chitinases in Chinese cabbage ( Brassica campestris L. ssp. pekinensis var. Granaat) plants treated with L-form bacteria of Pseudomonas syringae pv. phaseolicola during seed germination, was investigated using a fluorometric assay with 4-methylumbelliferyl substrates. The constitutive chitinase activities of seeds and seedlings were low and contrasted with much higher chitinase activities in seedlings treated with L-form bacteria. Maximum chitinase activities of seedlings treated with L-form bacteria was found 31 days after treatment. Extracts of the seedlings treated with L-form bacteria showed 4-fold and 1.5-fold endochitinase activities with, 4-methylumbelliferyl β- d- N-triacetylchitotrioside and 4-methylumbelliferyl β- d- N-tetraacetylchitotetraoside, respectively. Plant/L-form association was detected using a slide agglutination assay, enzyme linked immuno-sorbent assay and by re-isolation of bacteria from seedlings. L-form bacteria were also observed in root hairs using light microscopy. Re-isolation showed that L-forms were systemically distributed throughout the plant, with the highest population in roots. This was supported by ELISA results. Chinese cabbage seedlings treated with L-form bacteria had enhanced resistance to infection by the grey mould pathogen Botrytis cinerea.