- CHILLING INJURY IN TOMATO FRUIT 255
compounds such as 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-
2-ol (Ishida et al. 1998). In contrast, tomatoes from plants containing
antisensePSYhad a lower concentration of carotenoid-derived volatiles
(6-methyl-5-hepten-2-one, geranylacetone, and 훽-ionone) compared
with the wild type one (Baldwin et al. 2000). Since chilling tempera-
ture affects color development in tomato and volatile composition of
tomato is closely related to fruit color (Stevens 1970; Gao et al. 2008), it
is important to determine whether chilling-induced alteration in flavor
is independent of delayed ripening.
Ethylene plays an important role in enhancing biosynthesis of aroma
compounds in ripening fruit (Alexander and Grierson 2002). Since the
biosynthetic pathway of ethylene production is related to biotic and
abiotic stresses (Watkins and Ekman 2004), it is likely that altering
ethylene production during cool storage results in changes in aroma
development. Ethylene evolution results in enhancing biosynthesis of
aroma compounds such as hexanal,cis-3-hexenal,cis-3-hexenol, and
trans-2-hexenal during ripening (Baldwin et al. 1991). Generally, ethy-
lene affects essential enzymes involved in biosynthetic pathways that
influence the concentration of volatiles, including lipoxygenase (LOX),
alcohol dehydrogenase (ADH), and alcohol acyltransferase (AAT) (Zhu
et al. 2005; D ́ıazdeLeon-S ́ anchez et al. 2009). Lower concentrations of ́
aroma compounds in chilled tomatoes may result from lower enzyme
activity and reduced expression of genes encoding those enzymes (Bai
et al. 2011) or reduced rate of volatile emission due to low temperature
storage (Farneti et al. 2015).
A relationship between ethylene production, color development and
enhanced biosynthesis of aroma compounds during ripening has been
suggested (Alexander and Grierson 2002; Zhu et al. 2005). In tomato,
inhibition of ethylene production by suppression of ACS hinders nor-
mal ripening and reduces volatile compounds (Oeller et al. 1991) in
particular those that are carotenoid derived (Gao et al. 2007). Trans-
genic melon with antisense ACO treated with 1-MCP demonstrated
a 50% reduction in AAT activity and ultimate aroma development
(Flores et al. 2002). Application of aminoethoxyvinyl glycine (AVG,
ReTainTM—an ethylene synthesis inhibitor) or diazocyclopentadiene
(an ethylene action inhibitor) showed that biosynthesis of ester volatiles
by ripening apples required a high rate of ethylene production (Fan et al.
1998). However, inhibition of ethylene action by 1-MCP did not affect
tomato flavor dramatically (Mir et al. 2004), especially when pink matu-
rity tomatoes were treated with 1-MCP (Cliff et al. 2009). Baldwin et al.
(2011) did not find any detrimental effect of 1-MCP on flavor of breaker