LIBRO-CONGRESO-CITRUS

S09
S09O13
Potassium sorbate increases citrus weight loss in postharvest treatments but it does not provide
good decay control in wax
Parra J.P.
Postharvest Technology, Spain. encarna@citrosol.com
Potassium sorbate (PS) is a well-known and widely used food preservative. Among other applications, it
is used as a GRAS fungistatic postharvest treatment for citrus. We studied the efficacy of wax containing
increasing concentrations of PS on decay control of Penicillium digitatum, and its effect on fruit weight loss.
Decay control and weight loss increased with the concentration of PS in wax. Wax with typical amount of
2–5% PS showed poor decay reduction indices (around 20%), whereas fruit weight loss increased compared
with non-waxed control. Waxing the fruit reduced weight loss by 25%, but the addition of just 2% PS to the
wax caused an increase in fruit weight loss of almost 40% compared with waxed fruit. The hygroscopic effects
of PS are more damaging for citrus fruits with leaves. Leaves weight loss was very rapid when PS was added
to the wax, becoming desiccated in 24 hours, old and brittle. This issue is very important for the fresh packer
because these fruits are sold with leaves as proof of their freshness. Results of a similar study where PS
was applied to citrus as an aqueous treatment will be also presented. When applied in water, PS was more
effective for decay control than when applied in wax, but there was a considerable increase in fruit weight
loss. Combining aqueous PS with our Fortisol® Ca Plus phytofortifier completely solved the problem of weight
loss and achieved outstanding decay control, making these mixtures as promising treatments.
S09P01
Transcriptional regulation of the Citrus sinensis ABA-signalosome during fruit dehydration
Romero P., Rodrigo M.J., and Lafuente M.T.
Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Food Science. Postharvest Physiology and Biotechnology, Spain.
mtlafuente@iata.csic.es
Water stress is an important factor affecting fruit quality. Since abscisic acid (ABA) is a key regulator of the dehydration
response, understanding how the hormone is perceived will help to identify targets to improve drought hardiness
in horticultural crops. To study the involvement of the ABA perception system in the dehydration response of
citrus fruit, we have performed a comparative transcriptional analysis of the ABA-signalosome components in
water-stressed fruit of ‘Navelate’ orange (Citrus sinensis) and its fruit-specific ABA-deficient mutant ‘Pinalate’,
which is more prone to dehydration. No significant differences in the absolute expression levels of ABA receptors
(CsPYR/PYL/RCAR) were found between wild-type and mutant fruit, while those of the negative regulators
(CsPP2CA) were slightly lower in the mutant. Low differences in ABA receptors and downstream protein kinases
(CsSnRK2) transcripts levels were found in response to dehydration. Contrary, CsPP2CAs gene expression was
highly regulated by ABA content and showed differences between cultivars, which suggest that CsPP2CAs play a
key role regulating ABA response in citrus fruit to water stress. Results obtained by ABA application indicate that
although the mutant may sense ABA, the hormone signal could be impaired because of reduced CsPP2CAs levels.
Overall results highlight these components as potential targets to improve drought hardiness in citrus fruits.
S09P02
Delayed color break in ‘Tardivo’, a late ripening mandarin mutant, is related to a defective
ethylene response
Alos E. 1 , Distefano G. 2 , Rodrigo M.J. 1 , Gentile A. 2 , and Zacarias L. 1
1 Instituto de Agroquímica y Tecnología de Alimentos (IATA-CSIC), Food Science, Spain; and 2 University of Catania, Dipartamento di
Scienze delle Produzioni Agrarie e Alimentari, Italy. lzacarias@iata.csic.es
Late ripening mutants, with delayed peel color changes and senescence, are of paramount importance for the
citrus industry because they allow an extended harvesting and marketing period. Hence, the characterization
of these mutants constitutes a useful system to decipher the molecular bases that regulate the timing and
rate of color development in citrus fruits. Although the causes for these phenotypes may be diverse, recent
138 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012