250 P. BISWAS ET AL.
(Wang et al. 2006) and avocados (Dopico et al. 1993). However, it is
unclear whether inhibition of softening was simply a result of delayed
ripening due to chilling.
In short, severity of chilling damage, duration of low temperature
exposure, fruit maturity, and the activity of many enzymes and associ-
ated gene expression in a particular chilling temperature have to be con-
sidered before the mechanism of softening in chilling-induced tomato
can be elucidated. The way that fruit firmness is measured, whether
measured softening is a result of loss of turgor or loss of tissue integrity,
and the degree of CI severity (mild or severe), are all important fac-
tors that can contribute to inconsistent results reported in determin-
ing chilling-induced tomato softening. Since both ripening and chilling
induce fruit softening, it is important to differentiate chilling-induced
softening from softening associated with ripening in determining abnor-
mal texture that is usually reported as a result of low temperature
storage.
C. Increased Susceptibility to Decay
Increased susceptibility to decay is another CI symptom in tomato.
Species ofAlternaria,Phytophthora,Botrytis,andGeotrichumare some
of the major postharvest fungi andErwinia,Pseudomonas,andXan-
thomonasare common bacterial pathogens in tomato (Fallik et al. 1993).
Susceptibility to decay increases as fruit ripen normally (Fallik et al.
1993; Prusky 1996). However, when mature-green tomatoes are stored
below 12◦C for extensive periods, they show increased disease suscep-
tibility (Artes and Escriche 1994). Although mechanisms of ripening– ́
associated decay development may differ from chilling-induced decay,
increased decay susceptibility related to ripening and chilling could be
confounded during low temperature storage.
Among the different fungi,Alternariawas identified as the most fre-
quently isolated fungus in chill-injured tomatoes (Efiuvwevwere and
Thorne 1988).Alternariais a weak pathogen that usually develops on
the stem scar (Hall 1965) as natural resistance to pathogens is easily cir-
cumvented because of unavoidable wounding related to harvest. Entry
ofGeotrichumis usually via the stem scar, a wound or weak epidermal
tissue, while infection byFusariumis generally at a wound site (Bald-
win et al. 2011). Additionally, chilling-induced pitted tissue is often an
ideal entry point for microorganisms. In many cases, fungi enter through
areas of skin disrupted by mechanical damage (Barkai-Golan 2001).
Many factors play a vital role in inducing increased susceptibility
or resistance against pathogens. When a fruit is exposed to pathogen