COMPARATIVE EFFECTS OF CHITOSAN OLIGOMERS AND CELLOBIOSE ON THE CONTROL OF THE PHYTOPATHOGENIC FUNGUS Fusarium solani f. sp. eumartii

MANSILLA, A.Y.; TONÓN, C.V.; MENDIETA, J.R.; ALBERTENGO, L.; RODRIGUEZ, M.S.; CASALONGUÉ, C.A.

Cordoba

Congreso; XI Congreso Argentino de Microbiología General SAMIGE; 2015

SAMIGE

Fusarium spp are plant pathogens and soil saprophytes that cause a broad spectrum of diseases.Fusarium solani f sp eumartii (F. eumartii) is an economically important pathogen for potato andtomato crops. Currently, control of Fusarium spp relies on toxic and synthetic fungicides increasingpublic concern regarding environmental contamination and proliferation of resistance. Chitosan is anatural, non toxic copolymer of glucosamine and N-acetylglucosamine obtained by chitindeacetylation. This biopolymer and its oligosaccharides have potential applications in agriculture withregard to eliciting plant defense mechanisms and controlling plant diseases. On the other hand,cellobiose is a sugar obtained by cellulose degradation and its chemistry structure is similar tochitosan oligomers. The aim of this work is to give insights into the properties and mechanisms ofaction of chitosan oligomers (ChO) and cellobiose on the phytopathogenic fungus F. eumartii.Chitin was isolated from shrimp shells waste (Pleoticus mülleri). Chitosan was prepared byheterogeneous alkaline deacetylation of chitin and ChO were obtained by oxidative degradation.Cellobiose was purchased from Sigma-Aldrich (USA).Our findings revealed that, ChO and cellobiose-pretreated tomato seedlings were significant protectedagainst F. eumartii infection compared with control. Fungal lesion area and the inoculi remaining weresignificantly reduced in pre-treated seedlings. In order to provide a clue into the mechanism mediatedby ChO and cellobiose on disease control, chitinases were analyzed as defense markers in tomatoseedlings. Two isoforms of chitinases were accumulated in ChO and cellobiose-treated seedlingsevidencing activation of tomato defense responses of both compounds. Additionally, the effect of ChOand cellobiose on the mycelial growth was assessed. Meanwhile, ChO exerted inhibitory effects on F.eumartii growth; cellobiose did not show antimicrobial properties. Validation of inhibitory action of ChOon cell viability was demonstrated using propidium iodide as an intercalating agent excluded fromviable cells. All these findings pointed out that the assayed ChO has a great potential for controlling F.eumartii disease in plants. Its useful action could be due by, at least, two different mechanisms:antimicrobial and elicitor properties in tomato plants.