Postharvest Biology and Technology 20 2000 81 – 89
Catalase enzyme activity is related to tolerance of mandarin fruits to chilling
Jose M. Sala , Marı´a T. Lafuente
Instituto de Agroquı´mica y Tecnologı´a de Alimentos IATA
, Consejo Superior de In6estigaciones Cientı´ficas CSIC
, Apartado de Correos
73
, Burjassot
46100
, Valencia, Spain Received 17 December 1999; accepted 4 May 2000
Abstract
The effect of a postharvest hot-water dip treatment HWT at 53°C for 3 min and a 3-day heat-conditioning treatment at 37°C with air HAT at 90 – 95 RH on chilling tolerance and catalase CAT activity was compared in
‘Fortune’ mandarins. The HWT treatment increased CAT activity in the fruit, but after they were removed from high temperature to cold storage a rapid decline in CAT activity was associated with increased chilling injury. Greater
chilling tolerance and CAT activity was induced when fruits were conditioned for 3 days at 37°C and 90 – 95 RH. The CAT activity in fruits exposed to HAT was higher than in the dipped and the non-heated fruits over the storage
period at 2°C. An inhibitor of CAT activity, 3-amino-1,2,4-triazole AT, caused peel damage in HAT ‘Fortune’ mandarins and in the chilling-tolerant ‘Clementine’ and ‘Clemenules’ cultivars stored at 2°C but not at 12°C
non-chilling temperature. CAT activity was reduced about two to three times by AT upon cold storage in the cultivars studied. Little difference was found in the activity of ascorbate peroxidase APX, glutathione reductase
GR and superoxide dismutase SOD between AT-treated and non-treated fruits. The data indicate that CAT may be a major antioxidant enzyme involved in the defence mechanism of mandarin fruits against chilling stress. Our
results also suggest that the different effectiveness of the heat-conditioning treatments in increasing chilling tolerance of ‘Fortune’ mandarins may be related to induction of CAT activity during heating and on its persistence during cold
storage. © 2000 Elsevier Science B.V. All rights reserved.
Keywords
:
Acclimation; Catalase; Citrus fruit; Cold-stress; High-temperature conditioning; Hot-water dips; Oxidative stress www.elsevier.comlocatepostharvbio
1. Introduction
Exposure to low temperature causes chilling injury CI expressed as rind staining and peel
pitting in ‘Fortune’ mandarin fruits, whereas the cultivars ‘Clementine’ and ‘Clemenules’, are resis-
tant to CI. The CI-resistant cultivars can be stored at very low temperatures to extend the
market period, withstand long-distant transport or undergo quarantine treatments to control Med-
iterranean fruit fly Martı´nez-Ja´vega and Cu- querella, 1984; Sala, 1998. High-temperature
Corresponding author. Tel.: + 34-96-3900022; fax: + 34- 96-3636301.
E-mail address
:
ciesaliata.csic.es J.M. Sala. 0925-521400 - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 5 - 5 2 1 4 0 0 0 0 1 1 5 - 0
conditioning has been shown to increase chilling tolerance
in different
crops Lurie,
1998. Postharvest hot-water treatment HWT over
50°C for 1 – 3 min Wild 1990; Rodov et al., 1995; Schirra and Mulas, 1995 or hot air treat-
ment HAT at 35 – 37°C at high humidity for 1 – 3 days Ben-Yehoshua et al., 1987; Lafuente
et al., 1997 improve citrus fruit resistance to CI. Both heat pretreatments reduce CI in ‘Fortune’
mandarins Mulas et al., 1995; Gonzalez-Aguilar et al., 1997; Lafuente et al., 1997. However,
HWT treatments were not able to maintain the heat-induced resistance to cold stress after pro-
longed storage in ‘Fortune’ mandarins, whereas the HAT for 3 days at 37°C did so Mulas et al.,
1995.
Chilling temperatures may induce oxidative stress in plant tissues Purvis and Shewfelt,
1993, including fruits Hariyadi and Parkin, 1991; Sala, 1998. Sala 1998 found that the
main difference between chilling-sensitive and chilling-tolerant cultivars is in the higher ability
of the chilling-tolerant to break down H
2
O
2
by CAT activity and co-operation of APX and GR
activities. Subsequently, it was reported that heating ‘Fortune’ mandarins at 37°C for 3 days
induced 2.5-, 1.4-, and 1.2-fold increases in the activities of catalase CAT, superoxide dismu-
tase SOD and ascorbate peroxidase APX, re- spectively,
and that
the differences
in the
activities produced by the heat treatment were maintained during cold storage Sala and La-
fuente, 1999. In mustard seedlings, however, a heat acclimation treatment resulted in decreased
CAT activity during the induced thermoprotec- tion period Dat et al., 1998. Aminotriazole 3-
amino-1,2,4-triazole AT is an inhibitor of CAT activity in the presence of hydrogen peroxide,
and has been used to investigate the role of CAT in animals and plants exposed to different stress
conditions
Halliwell and
Gutteridge, 1993;
Prasad, 1997. We have tested the importance of CAT, APX,
GR and SOD on the tolerance of mandarin fruits to low-temperature stress, and the effect of
AT on response of chilling-tolerant ‘Clementine’ and ‘Clemenules’ mandarins and on the heat-in-
duced tolerance to cold stress in ‘Fortune’ man- darins. The effects of short HWT on CAT
activity and protection of fruit against CI under prolonged cold storage in relation to the mainte-
nance of the heat-induced CAT activity has also been investigated.
2. Material and methods
