GENE EXPRESSION DURING THE INFECTION PROCESS OF Colletotrichum truncatum (SCHWEIN.) IN MARADOL PAPAYA

Abstract

Colletotrichum truncatum (Schwein.) is one of the pathogenic fungi that causes anthracnose in papaya (Carica papaya L.). The objective of this study was to determine changes in gene expression related to the pathogenicity of C. truncatum in interaction with Maradol papaya leaves. Fungal spores were inoculated on detached leaves; tissue samples inoculated at the beginning (0 h) and at 2, 6, 16, 20, 24, 48, 60, 72, 96 and 120 hours after inoculation (hai) were analyzed. The relative expression of chitin synthase (CHS1), β-1-3 glucan synthase (GLS1) and cutinase (CUT1) genes was determined trough time. The CHS1 gene is always expressed and reached its maximum expression after 2 hai; the expression profile of the GLS1 gene coincided with that of CHS1 at the beginning of the infection, but at the end (120 hai) the expression of GLS1 increased significantly again. The expression of the CUT1 gene was considered late because the maximum was reached at 120 hai. These genes are related to the production of infection structures and pathogen development in Maradol papaya leaves during infection. Results suggest that the synthesis of chitin and β-1-3 glucans is associated with the stage of production of infection structures (appresoria, infection hyphae, conidia and acervuli) and that the function of cutinase ocurrs later, possibly during the lysis of the host cuticle.