Post harvest diseases fruits and vegetables - Xavier University ...

FREEDOM PALESTINE FREEDOM PALESTINE FREEDOM PALESTINE
Attack Mechanisms of the Pathogen 65
a-tomatine by virtue of their membrane composition or they are capable
of detoxifsdng a-tomatine. Detoxification of a-tomatine has been reported
for various fungi, such as Fusarium oxysporum f.sp. lycopersici (Ford et
al., 1977), Alternaria solani (Schlosser, 1975), Alternaria alternata
(Sandrock and VanEtten, 1997), Septoria lycopersici (Arneson and
Durbin, 1967), and Botrytis cinerea (Verhoeff and Liem, 1975).
In a recent study, Quidde et al. (1998) showed that B. cinerea
metabolizes a-tomatine by removal of the terminal D-xylose, to yield
Pi-tomatine, and not by deglycosylating a-tomatine completely, as was
previously suggested (Verhoeff and Liem, 1975). It was concluded that
the tomatinase of B, cinerea is a p-xylosidase. Using a tomatinasedeficient
strain of S. cinerea, Quidde et al. (1998) found that Pi-tomatine
is far less toxic to axenic culture than a-tomatine, confirming that the
removal of the xylose moiety represent a detoxification process. Most B.
cinerea strains tested, originating from various host plants, were found
capable of detoxifying a-tomatine in this way. It was thus suggested that
a-tomatine degradation has a role in the interaction between B, cinerea
and tomato.
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