Study of melanin produced in the grapevine phytopathogenic fungus Lasiodiplodia theobromae

RANGEL-MONTOYA EDELWEISS; PAOLINELLI MARCOS; HERNÁNDEZ-MARTÍNEZ RUFINA

Reims

Workshop; 10th International Workshop on Grapevine Trunk Diseases; 2017

Melanin is a pigment produced by oxidation ofphenolic and indole compounds. There are different types depending of their precursor. Lasiodiplodiatheobromae is a fungus from the Botryosphaeriaceaefamily and one of the most aggressive pathogensin grapevine, which cause grapevine decline. Associated with infection by this fungus, melanin isdeposited on the inner surface of cell walls, but itsparticipation in the process of infection of grapevineis unknown. The search for factors related with thepathogenicity of vascular pathogens is important,to enable an understanding of their interaction withtheir hosts. The aim of this work was to study the invitro behavior of L. theobromae str. UCD256Ma in thepresence of inhibitors of melanin and under differentstress conditions. Firstly, the fungus was grown in the presence of phthalide, tropolone and nitisinone,inhibitors of DHN-melanin, DOPA-melanin and pyomelanin, respectively. Then, the combined effectof these inhibitors with enzymatic lysis, H2O2, andUV radiation was evaluated and lastly, the ability ofthe fungus to use tyrosine as a carbon and nitrogensource. The growth of L. theobromae in the presence oftropolone at 15 μg·mL-1 was inhibited and it lost theability to degrade tyrosine. Exposure to H2O2 onlyaffected the growth of the fungus in the presence of15 μg·mL-1 tropolone. Total growth inhibition wasobserved with a combination of an enzymatic extractof Trichoderma asperellum and 15 μg·mL-1 tropolone.Finally, the viability of non-melanized spores was reduced under UV radiation. Based on these results, L.theobromae str. UCD256Ma is able to use tyrosine ascarbon and nitrogen source for its growth and perhaps as a melanin precursor; melanin protects thefungus against abiotic stress conditions and this fungus produces three types of melanin, with DOPAmelanin being the principal type produced.