Enzyme activities and pectin breakdown of sapodilla submitted to 1-methylcyclopropene

Enzyme activities and pectin breakdown of sapodilla submitted
1 5
Enzyme activities and pectin breakdown of sapodilla submitted
to 1-methylcyclopropene
Patrícia Lígia Dantas de Morais(1), Luiz Carlos de Oliveira Lima(2), Maria Raquel Alcântara de Miranda(3),
José Donizete Alves(3), Ricardo Elesbão Alves(4) and José Daniel Silva(3)
(1)Universidade Federal Rural do Semi-Árido, Caixa Postal 137, CEP 59625-900 Mossoró, RN, Brazil. E-mail: plmorais@hotmail.com
(2)Universidade Federal de Lavras, Caixa Postal 3037, CEP 37200-000 Lavras, MG, Brazil. E-mail: lcolima@ufla.br, jdalves@ufla.br (3)Universidade
Federal do Ceará, Caixa Postal 6039, CEP 60455-900 Fortaleza, CE, Brazil. E-mail: rmiranda@ufc.br (4)Embrapa Agroindústria Tropical,
Caixa Postal 3761, CEP 60511-110 Fortaleza, CE, Brazil. E-mail: elesbao@cnpat.embrapa.br
Abstract – The objective of this work was to investigate the influence of 1-methylcyclopropene (1-MCP) at
300 nL L-1 on activities of cell wall hidrolytic enzymes and pectin breakdown changes which Sapodilla (Manilkara
zapota cv. Itapirema 31) cell wall undergoes during ripening. Sapodilla were treated with ethylene antagonist
1-MCP at 300 nL L-1 for 12 hours and then, stored under a modified atmosphere at 25ºC for 23 days. Firmness,
total and soluble pectin and cell wall enzymes were monitored during storage. 1-MCP at 300 nL L-1 for 12 hours
delayed significantly softening of sapodilla for 11 days at 25ºC. 1-MCP postharvest treatment affected the
activities of cell wall degrading enzymes pectinmethylesterase and polygalacturonase and completely suppressed
increases in beta-galactosidase for 8 days, resulting in less pectin solubilization. ?eta-galactosidase seems
relevant to softening of sapodilla and is probably responsible for modification of both pectin and xyloglucan-
cellulose microfibril network.
Index terms: Manilkara zapota, beta-galactosidase, ripening.
Atividade de enzimas e degradação de pectinas de sapoti submetido
ao 1-metilciclopropeno
Resumo – O objetivo deste trabalho foi investigar a influência do 1-metilciclopropeno (1-MCP) nas atividades
das enzimas hidrolíticas da parede celular e nas mudanças na degradação da pectina durante o amadurecimento
de sapoti (Manilkara zapota cv. Itapirema 31). Frutos de sapotizeiro foram tratados com o inibidor da ação do
etileno, 1-MCP, na concentração de 300 nL L-1, por 12 horas e armazenados sob atmosfera modificada, à
temperatura de 25±2ºC, por 23 dias. A firmeza, conteúdo de pectina total e solúvel e enzimas da parede celular
foram avaliados durante todo o período de armazenamento. O 1-MCP a 300 nL L-1 por 12 horas retardou
significativamente o amolecimento de sapoti por 11 dias a 25ºC. O tratamento com 1-MCP afetou a atividade das
enzimas pectinametilesterase e poligalacturonase e inibiu o aumento da atividade beta-galactosidase por 8 dias,
e, conseqüentemente, resultou em menor solubilização das substâncias pécticas. A beta-galactosidase parece
ser relevante no amolecimento de sapoti e responsável pela modificação das pectinas e das xiloglucanas ligadas
as microfibrilas de celulose.
Termos para indexação: Manilkara zapota, beta-galactosidase, amadurecimento.
Introduction
wall and middle lamellae degradation by several
hydrolytic enzymes.
There is a great concern among growers and
Ethylene is the hormone responsible for triggering and
wholesalers on how to maintain the quality and nutritional
coordinating ripening events in climacteric fruits. Studies
attributes of tropical fruits in spite of the natural and
on gene expression demonstrated that ripening is a
rapid process of senescence. Ripening is the irreversible
programmed event that involves the controlled expression
first step of senescence and the most characteristic
of specific genes, of which some are ethylene-dependent
alteration fruits undergo during ripening is softening or
(Giovannoni, 2001). Thus, if technologies are to be
loss of firmness of skin and flesh, a consequence of cell
developed to maintain quality and enhance postharvest
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1 6
P.L.D. de Morais
conservation of commodities, it needs to be based on
releasing the gas from a commercial powdered
previous knowledge of the physiological processes that
formulation (Smartfresh from Rohm and Haas) with
control ripening and senescence.
0.14% of the active ingredient. Control fruit (not exposed
The use of ethylene antagonists has been an important
to 1-MCP) were maintained under identical conditions.
tool in clarifying the physiological role of ethylene in the
Immediately after chambers were opened, fruit were
process of fruit ripening and also as a postharvest
placed on polystyrene trays, four fruits per tray, and
treatment to broaden the conservation potential of fruits.
covered with 12 µm PVC film and then stored at 25±2ºC
1-Methylcyclopropene (1-MCP) is the best known and
and 70±5% RH for 23 days. Samples of fruit were
studied amongst ethylene inhibitors and has been shown
evaluated on harvest day and after 4, 8, 11, 14, 17, 20,
to influence various physiological responses during fruit
and 23 days for firmness, cell wall structural
ripening, as ethylene production, respiratory rate, weight
polysaccharides and for cell wall enzymes. After firmness
loss and cell wall degradation (Blankeship & Dole, 2003).
was measured, fruit were peeled and mesocarpic tissue
1-MCP postharvest treatment reduced the activity of
from each fruit were stored at -70oC and used for
cell wall enzymes and delayed ripening of avocados for
analysis.
four days (Jeong et al., 2002). Pears and plums treated
Fruit firmness was measured on a TA.XT2i Stable
with 1-MCP showed a reduction in ethylene production
Micro Systems automatic texture analyzer with a 6 mm
and respiratory rate (Dong et al., 2001; Mathooko et al.,
plunger. Measurements were performed at two
2001).
equidistant points on the equatorial region of whole,
Sapodilla (Manilkara zapota) is a climacteric fruit
unpeeled fruits and results expressed in Newton (N).
that ripens shortly after harvest, within 8 to 10 days at
Pectinmethylesterase (PME, E.C. 3.1.1.11) was
26°C and 55%RH (Morais et al., 2006). The studies on
extracted and measured using modifications of the
sapodilla were mainly restricted to storage life
method of Jen & Robinson (1984). Mesocarp tissue (5 g)
extension using low temperatures and modified
was homogenized with 25 mL of ice-cold 0.2 N NaCl in
atmosphere (Miranda et al., 2001), until Morais et al.
a Polytron. The homogenate was filtered through
(2006) tested different concentrations (100, 200 and
Whatman No. 1 paper and the residue collected as the
400 nL L-1) of 1-MCP on sapodilla. Postharvest
enzyme crude extract. These former procedures were
treatment with 1-MCP at 200 and 400 nL L-1 delayed
carried out at 4oC. For PME activity assay, the reaction
firmness loss and changes in pulp color, in sapodilla.
mixture contained 5 mL of enzyme crude extract and
This work investigated the influence of 1-MCP at
30 mL of pectin solution (1% v/w citrus pectin in 0.1 M
300 nL L-1 on activities of cell wall hidrolytic enzymes
NaCl) and the rate of pectin demethylation was monitored
and cell wall pectin breakdown during ripening of
through titration with NaOH 0.025 M at pH 7.0 for 10 min.
sapodilla.
One unit of pectinmethylesterase was defined as the amount
of enzyme capable of demethylating pectin corresponding
Materials and Methods
to the consumption of 1 nmol NaOH min-1 g-1 and results
were expressed as one unit of activity per minute per gram
Sapodilla (Manilkara zapota) cultivar Itapirema-31
fresh matter.
was harvested fully grown at physiological maturity from
Polygalacturonase (PG, E.C. 3.2.1.15) was extracted
a commercial grower in Paraipaba, Ceará State, Brazil,
as described by Buescher & Furmanski (1978) and its
and transported to Postharvest Physiology and
activity was determined according to Pressey & Avants
Technology Laboratory in Fortaleza within 10 hours from
(1973). Mesocarp tissue (5 g) was homogenized with
harvest. Fruit were selected for uniformity of size and
50 mL of ice-cold water. The homogenate was filtered
developmental stage, and then soaked in 1,000 mg L-1
through Whatman No. 1 paper; the residue was washed
Benomil fungicide for five minutes, rinsed and dried. Fruit
in 20 mL of ice-cold water and then resuspended in
were sorted into two groups, one was treated with
20 mL of 1.0 N NaCl and stirred for 1 min. It was then
300 nL L-1 1-MCP for 12 hours and the other was control
adjusted to pH 6.0 let to rest for 1 hour. The volume
(0 nL L-1 1-MCP).
was completed to 30 mL with 1.0 N NaCl and filtered
Fruit were exposed to 300 nL L-1 of 1-MCP in
through Whatman No. 1 paper and the residue collected
hermetically closed 186-L mini-chambers at 25±2ºC for
as the enzyme crude extract. All previous steps were
12 hours. The concentration used was achieved by
conducted at 4oC. For PG activity assay, the reaction
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Enzyme activities and pectin breakdown of sapodilla submitted
1 7
mixture consisted of 200 µL enzyme crude extract plus
23 days, no significant differences in firmness were found
50 µL 0.25% polygalacturonic acid in 37.5 mM sodium
between 1-MCP treated and controls. The sharp
acetate buffer, pH 5.0. The reaction mixture was
decrease in firmness of control fruit observed up to day 8
incubated for three hours at 30oC followed by a boiling
could be correlated to the climacteric ethylene synthesis
water bath to stop the reaction. The reducing groups
(Miranda et al., 2002) and after that, firmness of control
liberated were determined according to Somogyi
fruit decreased slowly and continuously.
technique modified by Nelson (1944). Results were
These results support the observation of Araújo-Neto
expressed as units of PG activity per minute per gram
et al. (2001) that sapodilla 'Itapirema-31', stored for
fresh matter.
8 days at 24ºC with no postharvest treatment, exhibited
Beta-galactosidase (?-GAL, E.C. 3.2.1.23) was
a firmness loss from 78.6 N to 5.49 N. It was also
extracted as described by Kitagawa et al. (1995) and its
observed that 1-MCP kept firmer for a longer period:
activity determined as Dey & Pridham (1969). Mesocarp
peaches, plums and apricot (Lurie & Weksler, 2005) and
tissue (10 g) was homogenized with 20 mL of 0.1 M acetate
'Simmonds' avocado (Jeong et al., 2002). The delay in
phosphate buffer, pH 5.0, with 1% polyvinylpyrrolidone
softening observed in 1-MCP treated sapodilla indicates
(PVP) and centrifuged (10,000 g, 15 min). The pellet was
the importance of ethylene to ripening of climacteric fruits
resuspended in 0.1 M acetate phosphate buffer, pH 5.0,
and the ability of the 1-MCP treated fruit to soften at
plus 0.005 M 2-mercaptoethanol and then centrifuged
the end of storage suggests that new ethylene cell
(10,000 g, 15 min). The pellet was resuspended in
membrane receptors were synthesized and cells regained
0.02 M sodium acetate buffer, pH 5.0, plus 3 M NaCl and
their sensibility to this hormone, as sapodilla ripened
stirred for 12 hours. The suspension was centrifuged
regularly.
(14,000 g, 20 min) and the supernatant dialyzed for 24 hours
The reduction in firmness observed as fruits ripen is
against water. All previous steps were conducted at 4oC.
mostly a consequence of modifications on cell wall
The beta-galactosidasic activity was assayed for hydrolysis
carbohydrate metabolism and on its structure (Ali et al.,
of p-nitrophenil-?-galactopyranoside and the reaction
2004). Fruit firmness is considered one of the main
mixture consisted of crude enzyme extract and 0.003 M
quality attributes and often limits postharvest shelf life.
substrate in McIlwaine buffer, pH 4.0. After 15 min at
In the case of sapodilla, whenever the fruit is apt for
37oC, the reaction was terminated by 0.1 M sodium
consumption, it is so soft that it is very susceptible to
carbonate and the p-nitrophenol released was measured
mechanical damage and pathogen attack.
spectrometrically at 400 nm. Results were expressed as
In sapodilla cell wall, the soluble pectin content
units of beta-galactosidase activity per minute per gram
increased through storage with significant differences
fresh matter.
between treatments (Figure 2). The total pectin content
The experiment was conducted in a 2x8 factorial
design with a treatment defined as the 1-MCP dosage
(300 nL L-1) plus control and eight times of evaluation
(0, 4, 8, 11, 14, 17, 20, and 23 days). The experimental
parcels were made up of 12 fruits, being three repetitions
with four fruits each. Data were analyzed as averages
of 12 determinations±standard deviation and by ANOVA,
using SISVAR.
Results and Discussion
Sapodilla treated at postharvest with 1-MCP at
300 nL L-1 softened much slower than control
fruit (Figure 1). After 8 days of storage at 25ºC and 70%
RH, firmness of control fruit decreased from 79.74 N
Figure 1. Changes in firmness during postharvest storage of
at harvest day to 7.79 N. Meanwhile, softening of
sapodilla treated with 300 nL L-1 1-methylcyclopropene
1-MCP treated fruit was significantly delayed, reaching
(1-MCP) ( ) for 12 hours and control ( ), at 25±2°C and
15.37 N after 11 days of storage. After storage for
70±5% RH.
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1 8
P.L.D. de Morais
of sapodilla cell wall also exhibited significant differences
after 21 days. Vilas Boas et al. (2000) reported synthesis
between 1-MCP-treated and control fruit (Figure 3). At
of pectin during storage of tomatoes and Pinheiro et al.
harvest day, the total pectin level was 630.52 mg 100 g-1
(2007) also verified similar 1-MCP effects on soluble
and for control fruit, the increase in soluble forms is
and total pectin contents as bananas ripened. This
consistent with the decline in total pectin levels during
increase in soluble forms of pectic substances is
sapodilla ripening and could be explained by a faster
concomitant to firmness loss, observed during fruit
metabolic rate resulting in greater solubilization of pectin.
ripening.
1-MCP-treated sapodilla showed a smaller increase
Regarding their external appearance, control fruits
in soluble pectin levels and maintained high total pectin
started to show senescence symptoms after 15 days of
contents through storage, corroborating to the idea that
storage, meanwhile those treated with 1-MCP showed
1-MCP maintains firmness due to inhibition of cell wall
the same symptoms only after 21 days of storage.
degradation. Pectin was synthesized at the beginning of
Miranda et al. (2001) observed, in physiologically mature
storage of 1-MCP-treated fruits and started to decline
sapodilla, similar total and soluble pectin contents
compared to those reported here and also a similar
pattern of conversion of total to soluble forms as fruit
ripened.
The softening process is thought to be a consequence
of de-esterification of pectin catalyzed by PME followed
by pectin depolymerization catalyzed by PG, thus PG
activity is dependent on PME for making substrate
available (Abu-Goukh & Bashir, 2003). Cell wall PME
activities were high in sapodilla (Figure 4). In control
fruit, PME activity increased gradually until day 11
reaching ca. 480 activity units and then started to
decrease. Previous works reported similar activity
patterns for PME in sapodilla, guava, papaya and
“carambola” (Miranda et al., 2001; Abu-Goukh & Bashir,
Figure 2. Changes in soluble pectin content during
postharvest storage of sapodilla treated with 300 nL L-1
2003; Ali et al., 2004).
1-methylcyclopropene (1-MCP) ( ) for 12 hours and
When sapodilla was treated with 1-MCP, PME
control ( ), at 25±2°C and 70±5% RH.
maximum activity was delayed to day 14 and reached
Figure 3. Changes in total pectin content of 'Itapirema 31'
Figure 4. Changes in pectinmethylesterase (PME) activity
sapodilla treated with 300 nL L-1 1-methylcyclopropene
during postharvest storage of sapodilla treated with
(1-MCP) ( ) for 12 hours and control ( ) stored under modified
300 nL L-1 1-methylcyclopropene (1-MCP) ( ) for 12 hours
atmosphere at 25±2°C and 70±5% RH.
and control ( ), at 25±2°C and 70±5% RH.
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Enzyme activities and pectin breakdown of sapodilla submitted
1 9
lower levels (ca. 440 activity units), showing that
main responsible for tomato softening, since in transgenic
although PME activity was not suppressed by 1-MCP,
tomatoes, the inhibition of PG activity had very little effect
its induction was restricted. In sapodilla, the high pectin
on firmness loss. In sapodilla, the low PG activity
demethylesterification activity catalyzed by PME is
reported in this study and in previous work (Miranda
probably required not only for subsequent PG activity,
et al., 2001) indicates also that it is not the main
which was very low as observed in Figure 5, but also to
responsible for softening.
modify pH and cation exchange properties of cell wall,
At harvest day, there was no detectable
which might impact other cell wall enzymes. In bananas,
beta-galactosidase activity in sapodilla, but as ripening
1-MCP treatment did not delay PME peak activity;
progressed there was a significant increase in activity in
although the levels were markedly lower indicating that
control fruit (Figure 6). In control fruits, beta-
cell wall hydrolases are largely dependent on ethylene
galactosidase activity reached 352.5 UAE min-1 g-1 at
production and perception (Lohani et al., 2004).
day 4, meanwhile the 1-MCP treated fruit reached
PG activity increased during storage, reaching a
432.80 UAE min-1 g-1 only at day 14. The delay in
maximum (ca. 9 activity units) on days 8 and 14 for
beta-galactosidase activity observed in 1-MCP treated
control and 1-MCP treated sapodilla, respectively
sapodilla indicates the importance of ethylene to the
(Figure 5) and then decreased. The 1-MCP treatment
activity of this cell wall hydrolase. Consistent with the
delayed PG peak, although the activity levels were
significantly low for both treatments. Low activity values
marked initial suppression of beta-galactosidase levels
presented for PG were similar to those observed by
in 1-MCP-treated sapodilla, softening was significantly
Miranda et al. (2001) for sapodilla stored under ambient
delayed.
and modified atmosphere.
Studies on gene expression in tomatoes showed an
During ripening of avocado and banana, PG activity
increase in expression of beta-galactosidase gene during
was very low in pre-climacteric stage then, increased
climacteric and when fruits were treated with exogenous
as climacteric proceeded and continued increasing during
ethylene (Moctezuma et al., 2003). These authors
postclimacteric phase. In both cases, PG activity was
suggested the use ethylene antagonists or inhibitors,
preceded by PME (Jeong et al., 2002; Lohani et al.,
as 1-MCP, to slow the activity of beta-galactosidase and
2004). When avocado were treated with 1-MCP, PG
prolong the postharvest life of tomatoes. When
activity was not recovered although firmness reached
values similar to control (Jeong et al., 2002).
beta-galactosidase was inhibited, there was a great
For quite some time, changes in firmness observed
reduction in tomato firmness loss (Alexander & Grierson,
during ripening were mainly credited to pectin hydrolyses
2002). Miranda et al. (2001) reported that beta-
by PG. Now, there is evidence that other mechanisms
galactosidase activity increased as sapodilla softened and
are also involved with fruit softening (Redgwell & Fischer,
observed through microscopic analysis the loosening of
2002). Giovannoni (2001) observed that PG is not the
cell wall, to which beta-galactosidase is associated.
Figure 5. Changes in polygalacturonase (PG) activity during
Figure 6. Changes in beta-galactosidase activity during
postharvest storage of sapodilla treated with
postharvest storage of sapodilla treated with
300 nL L-1 1-methylcyclopropene (1-MCP) ( ) for 12 hours
300 nL L-1 1-methylcyclopropene (1-MCP) ( ) for 12 hours
and control ( ), at 25±2°C and 70±5% RH.
and control ( ), at 25±2°C and 70±5% RH.
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P.L.D. de Morais
Conclusions
KITAGAWA, Y.; KANAYAMA,Y.; YAMAKI, S. Isolation of
?-galactosidase fractions from Japanese pear: activity against native
1. The effects of 1-methylcyclopropene on firmness
cell wall polysaccharides. Physiologia Plantarum, v.93,
loss result from restricted induction or inhibition of cell
p.545-550, 1995.
wall hydrolytic enzymes as pectinamethylesterase,
LOHANI, S.; TRIVEDI, P.K.; NATH, P. Changes in activities of
polygalacturonase and beta-galactosidase leading to
cell wall hydrolases during ethylene-induced ripening in banana: effect
lower pectin solubilization.
of 1-MCP, ABA and IAA. Postharvest Biology and Technology,
v.31, p.119-126, 2004.
2. The softening phenomenon of sapodilla should be
mainly attributed to modification of pectin network
LURIE, S.; WEKSLER, A. Effects of 1-methylcyclopropene on
stone fruits. Acta Horticulturae, v.682, p.85-90, 2005.
brought about by beta-galactosidase.
MATHOOKO, F.M.; TSUNASHIMA, Y.; OWINO, W.Z.O.;
KUBO, Y.; INABA, A. Regulation of genes encoding ethylene
References
biosynthetic enzymes in peach (Prunus persica L.) fruit by carbon
dioxide and 1-methylcyclopropene. Postharvest Biology and
ABU-GOUKH, A.B.A.; BASHIR, H.A. Changes in pectic enzymes
Technology, v.21, p.265-281, 2001.
and cellulase activity during guava fruit ripening. Food Chemistry,
v.83, p.213-218, 2003.
MIRANDA, M.R.A.; SILVA, F.S.; ALVES, R.E.; FILGUEIRAS,
H.A.C.; ARAUJO, N.C.C. Storage of two types of sapodilla under
ALEXANDER, L.; GRIERSON, D. Ethylene biosynthesis and
ambient condition. Revista Brasileira de Fruticultura, v.24,
action in tomato: a model for climacteric fruit ripening. Journal of
p.644-646, 2002.
Experimental Botany, v.53, p.2039-2055, 2002.
MIRANDA, M.R.A.; SILVA, F.S.; FILGUEIRAS, H.A.C.; ALVES,
ALI, Z.M.; CHIN, L.H.; LAZAN, H. A comparative study on wall
R.E.; ARÁUJO, N.C.C. Enzymes and pectin breakdown of sapodilla
degrading enzymes, pectin modifications and softening during
during modified atmosphere storage. Proceedings of the
ripening of selected tropical fruits. Plant Science, v.167,
Interamerican Society for Tropical Horticulture, v.45, p.18-21,
p.317-327, 2004.
2002.
ARAUJO-NETO, S.E.; PRACA, E.F.; CARVALHO, E.F.; ALVES,
MOCTEZUMA, E.; SMITH, D.L.; GROSS, K.C. Effect of ethylene
R.E.; MENEZES, J.B.; MORAIS, E.A. Determinação do ponto de
on mRNA abundance of three ?-galactosidase genes in wild type and
colheita e índices de maturação para sapoti (Manilkara achras).
mutant tomato fruit. Postharvest Biology and Technology, v.28,
Revista Brasileira de Fruticultura, v.23, p.45-49, 2001.
p.207-217, 2003.
BLANKENSHIP, S.M.; DOLE J.M. 1-Methylcyclopropene: a
MORAIS, P.L.D.; LIMA, L.C.O.; ALVES, R.E.; FILGUEIRAS,
review. Postharvest Biology and Technology, v.28, p.1-25, 2003.
H.A.C.; ALMEIDA, S.A. Alterações físicas, fisiológicas e químicas
BUESCHER, R.W.; FURMANSKI, R.J. Role of pectinesterase and
durante o armazenamento de duas cultivares de sapoti. Pesquisa
polygalacturonase in the formation of woolliness in peaches. Journal
Agropecuária Brasileira, v.41, p.549-554, 2006.
of Food Science, v.43, p.264-266, 1978.
NELSON, N.A. A photometric adaptation of Somogyi method for
DEY, P.M.; PRIDFHAM, J.B. Purification and properties of
the determination of glucose. The Journal of Biological
?-galactosidases from Vicia faba seeds. Biochemistry Journal,
Chemistry, v.153, p.375-380, 1944.
v.113, p.49-55, 1969.
PINHEIRO, A.C.M.; VILAS BOAS, E.V.B.; ALVES, A.P. ; SELVA,
DONG, L.; ZHOU, H.W.; SONEGO, L.; LERS, A.; LURIE, S.
M.L. Amadurecimento de bananas ‘Maçã’ submetidas ao
Ripening of 'Red Rosa' plums: effect of ethylene and
1-metilciclopropeno. Revista Brasileira de Fruticultura, v.29,
1-methylcyclopropene. Australian Journal of Plant Physiology,
p.1-4, 2007.
v.28, p.1039-1045, 2001.
PRESSEY, R.; AVANTS, J.K. Separation and characterization of
GIOVANNONI, J. Molecular biology of fruit maturation and
endopolygalacturonase and exopolygalacturonase from peaches.
ripening. Annual Review of Plant Physiology and Plant
Plant Physiology, v.52, p.252-256, 1973.
Molecular Biology, v.52, p.725-749, 2001.
REDGWELL, R.R.; FISCHER, M. Fruit texture, cell wall metabolism
JEN, J.J.; ROBINSON, M.L.P. Pectolytic enzymes in sweet bell
and consumer perceptions. In: KNEE, M. (Ed.). Fruit quality and
peppers (Capsicum annuum L.). Journal of Food Science, v.49,
its biological basis. Sheffield: Sheffield Academic Press, CRC Press
p.1085-1087, 1984.
LLC., 2002. p.46-88.
JEONG, J.; HUBER, D.J.; SARGENT, S. Influence of
VILAS BOAS, E.V.B.; CHITARRA, A.B.; MALUF, W.R.;
1-methylcyclopropene (1-MCP) on ripening and cell-wall matrix
CHITARRA, M.I.F. Modificações texturais de tomates
polysaccharides of avocado (Persea americana) fruit. Postharvest
heterozigotos no loco alcobaça. Pesquisa Agropecuária Brasileira,
Biology and Technology, v.25, p.241-256, 2002.
v.35, p.1447-1453, 2000.
Received on July 20, 2007 and accepted on December 3, 2007
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