The first barrier to penetration and proliferation
of pathogenic microorganisms is the plant cuticle.
To breach the plant cuticle, fungi can either utilize
coordinately regulated cell wall-degrading
enzymes (Tonukari et al. 2000) or generate invasive
forces (by accumulating glycerol up to 3 M in
the appressorium generating a very high hydrostatic
pressure) to break the cuticle mechanically
(Bechinger et al. 1999). Melanin-deficient
mutants do not generate appressorial turgor and
are non-pathogenic (Thines et al. 2000).
Colletotrichum kahawae Bridge & Waller and
C. gloeosporioides Penz are two fungal species
that infect coffee. The former is responsible for
the coffee berry disease (CBD) in Africa, infecting
leaves and coffee berries at any stage of their
development and leading to losses by 70–80%
(Chen et al. 2005). The latter only infects the
coffee berries at the ripe stage with no significant
yield reduction. Turgor pressure (TP) of the
C. kahawae appressorium is the main factor for its
penetration through plant cuticle (Chen et al.
2004). The TP of the unmelanized appressorium
induced in vitro by tricyclazole was 25% of the
melanized one, leading to reduced infection on
leaves and green berries (Chen et al. 2004).
Epicatechin is the second major phenolic
compound in coffee pulp, accounting for 22% of
the total phenolic compounds (Ramirez-Martinez
et al. 1988). Catechin has antibacterial effects
(Hirasawa and Takada 2004) and also directly
inhibits several fungal enzyme activities in vitro
(Niu et al. 2004; Prusky et al. 1988). The aim of
this study was to investigate the possible role of
epicatechin and catechin in fungal penetration.