LIBRO-CONGRESO-CITRUS

experimental evidences in mandarin fruit link delayed degreening with differential ethylene sensitivity.
‘Tardivo’ is a late ripening mutant of clementine mandarin that displays a certain inability to ethylene induceddegreening.
In the present work, we have explored if this phenotype is associated with differential responses
to ethylene-regulated gene expression. To this end we have analyzed the expression of key genes involved
in carotenoid, ABA and phenylpropanoids biosynthesis and also in the ethylene biosynthetic and signaling
pathways. Results indicate an altered ethylene-induced gene expression in ‘Tardivo’ fruits, displaying a
transient response to ethylene that is unable to sustain it subsequently.
S09P03
Comparative proteome and metabolome profiling analysis heat treatment induced fruit
resistibility during postharvest storage
Yun Z., Liu P., Liu S.Z., Luo T., Jin S., Gao H.J., Xu Q., Xu J., Cheng Y.J., and Deng X.X.
Key Laboratory of Horticultural Plant Biology of Ministry of Education, Huazhong Agricultural University, China.
yjcheng@mail.hzau.edu.cn
From harvest to human consumption, the commercial production of fresh fruits requires time for shipping,
storage and marketing. During these processes, physiological disorders and pathological diseases are the main
causes of fruit loss. Heat treatment (HT) has been widely used to maintain fruit quality during postharvest
storage. However, little information is available related to the underlying mechanisms occurring during
storage at a systemic biological level. ‘Kamei’ Satsuma mandarin (Citrus unshiu) fruits were selected for use in
exploring the mechanisms induced by HT which allow fruit to resist such damage during postharvest storage.
Proteome and metabolome studies were conducted based on two-dimensional gel electrophoresis (2-DE), gas
chromatography coupled to mass spectrometry (GC-MS), and liquid chromatography/electrospray ionisation
time-of-flight mass spectrometry (LC/QTOF-MS). The results showed resistance associated proteins were upregulated,
such as beta-1, 3-glucanase, Class III chitinase, 17.7 kDa heat shock protein and low molecular
weight heat-shock protein. This study provides new insights into HT induced fruit resistance to pathogens and
physiological disorders. Interpretation of the data for the proteins and metabolites revealed reactive oxygen
species (ROS) play an important role in HT induced fruit disease and stress resistance. Redox metabolism
proteins were down-regulated in HT fruits while the intracellular H2O2 content decreased in HT fruits, which
might increase fruit resistibility in response to external stress. Also, flavonoids were up-regulated in HT fruits,
a process which was directly involved in the response to external stress. Moreover, the H2O2 in the fruit was
used to synthesize lignin, which leads to increased lignin content in HT fruits. The increased lignin-induced
thickening of cell walls was involved in isolating external pathogens from fruits.
S09P04
Postharvest water stress leading to peel disorders in citrus fruit involves regulation of
phospholipases by ABA
Romero P., Gandia M., and Alférez F.
Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Laboratorio De Fisiología y Biotecnología Postcosecha, Spain.
alferez@iata.csic.es
The interplay between abscisic acid (ABA) and phospholipases A2 and D (PLA2 and PLD) in the response
of citrus fruit to water stress was investigated during postharvest by using an ABA-deficient mutant from
‘Navelate’ sweet orange. Fruit from both varieties were subjected to prolonged water stress conditions
inducing non-chilling peel pitting in the rind. Treatment with phospholipase inhibitors reduced the disorder in
both varieties suggesting that phospholipid metabolism is involved in citrus peel quality. Expression of genes
encoding PLA2 and PLD was studied by real time RT-PCR during water stress and in response to ABA. Expression
of CsPLA2α was dependant on ABA in fruit from both varieties, since ABA application restored expression in
the mutant, showing for the first time the involvement of this hormone in the activation of PLA2. CsPLDα
expression increased with dehydration in mature-green fruit from ‘Navelate’ but not in the mutant and ABA
did not counteract this effect, suggesting that ABA deficiency in the mutant impairs sensitivity. Our results
show interplay between PLA2 and PLD substrates and products, and suggest that ABA action is upstream
phospholipase activation in response to water stress.
XII INTERNATIONAL CITRUS CONGRESS 2012 - 139
S09