Melanins from two selected isolates of Pseudocercospora griseola grown invitro: Chemical features and redox activity

ALEJANDRA BÁRCENA; MARIA FERNANDA ROZAS; MARIO C.N. SAPARRAT; ANA GENNARO; PEDRO A. BALATTI; MARIELA BRUNO; MARÍA V. MIRÍFICO

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2018 vol. 186 p. 207 - 215

1011-1344

Pseudocercospora griseola is the causal agent of Angular Leaf Spot (ALS), a disease of common bean. Due to itscoevolution with beans, two major groups have been defined, ?Andean? (P. griseola f. griseola) and?Mesoamerican? (P. griseola f. mesoamericana). The aim of this study was to characterize the dark pigment,melanin, synthetized by a selected isolate of each genic group of P. griseola when grown on Potato-dextrosebroth. P. griseola f. griseola isolate S3b and P. griseola f. mesoamericana isolate T4 produced 1.7 ± 0.6 and4.1 ± 0.9 mg of melanin per g of dry biomass, respectively. Although both melanins possessed similarUV?visible absorption spectroscopic pattern, P. griseola f. mesoamericana isolate T4 melanin had a lowerUV?visible absorption, higher reducing activity and metal chelating ability than melanin from P. griseola f.griseola isolate S3b. However, when the size of the sample was 10 mg S3b melanin had a higher content of freephenolic groups. Furthermore, cell wall polysaccharides modified in melanin the availability of active phenolicgroups, which was dependent on the fungal isolate and the size of the sample. Therefore, the amount andchemical features of melanin as well as its deposition in mycelium walls within isolates is different, which mightexplain the different pigmentation and physiological behaviours of these representatives of the two groups of P.griseola.