Publications (10)0 Total impact
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Article: Spatial study of antioxidant enzymes, peroxidase and phenylalanine ammonia-lyase in the citrus fruit-Penicillium digitatum interaction
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ABSTRACT: Changes in the activities of the antioxidant enzymes, superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11) and glutathione reductase (GR; EC 1.6.4.2), as well as in soluble and insoluble peroxidase (POD; EC 1.11.1.7) and in phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) activity and Pal transcript levels in flavedo and albedo tissues of citrus fruit infected with Penicillium digitatum have been examined. Specific probes corresponding to a fragment of the large subunit of the nuclear rRNA from both organisms have been cloned and used to determine the advance of the fungus through the fruit. The activities of all the enzymes were higher in non-infected areas of the flavedo than in the albedo, a fact that may be related to the higher resistance of the flavedo to infection by the pathogen. In both tissues, the activity of the antioxidant enzymes decreased at different rates with the advance of the fungus, except for CAT and soluble POD activities that increased in the area of the flavedo completely colonized by the fungus. On the other hand, the flavedo, but not the albedo, was able to respond to pathogen attack by increasing insoluble POD and PAL activities and Pal transcript levels. However, discrepancies between PAL activity and mRNA levels suggest the ability of P. digitatum to suppress this defense response. Thus, the present study shows that in the interaction between citrus-P. digitatum both host defense responses and pathogen virulence mechanisms are taking placePostharvest Biology and Technology. 39(2):115-124. -
Article: Biochemical and molecular characterization of induced resistance against Penicillium digitatum in citrus fruit
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ABSTRACT: To get an insight into the mechanisms underlying resistance of citrus fruit against Penicillium digitatum, we have analyzed at the enzyme activity and gene expression levels the possible involvement of phenylalanine ammonia-lyase (PAL), peroxidase, [beta]-1,3-glucanase and chitinase in the flavedo (outer colored part of the fruit peel) and albedo (the inner white part) in elicited fruit. As a tool to induce resistance, we inoculated oranges with P. digitatum and 1 d later fruit were exposed to a hot air treatment at 37 °C for 3 d. All enzyme activities increased in parallel with increased resistance, especially in the albedo, although the highest activities were generally found in the flavedo. Expression of the gene encoding PAL and that of the genes coding for the basic, rather than for the acidic, isoforms of the PR proteins was also induced in both tissues, but most markedly in the albedo.Postharvest Biology and Technology. 56:31-38. -
Article: Genomic approaches to postharvest biotic and abiotic stresses of citrus fruit
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ABSTRACT: Citrus fruit may be subjected to biotic and abiotic stresses during postharvest handling and storage that influence their marketability. The major biotic stress is caused by phytopathogenic fungi of the genus Penicillium, being P. digitatum the most important pathogen. Among the abiotic stresses, we are particularly interested in chilling injury and in the heat-induced chilling tolerance of chilling-sensitive citrus cultivars. To gain a deeper knowledge on the mechanisms underlying the defence response of Citrus fruit to pathogen attack and on the heat-induced chilling tolerance, we have undertaken two complementary approaches. In the framework of the Spanish “Citrus Functional Genomic Project, CFGP” we have generated one cDNA library for each condition that will allow us to get a general picture of the genes being transcribed under these conditions. The abiotic stress library was obtained by pooling RNA from the flavedo of mandarin fruits that were heat-conditioned at 37°C for up to three days followed by storage at 2°C for up to ten days. The biotic stress cDNA library was obtained from the rind of orange fruits 24 h after inoculation with P. digitatum. For each library, a total of 1152 clones have been analysed. A more directed approach has been the utilization of the Suppression Subtractive Hybridization technique to generate subtracted cDNAs libraries enriched in those genes preferentially expressed under a particular condition. In this paper we present an overall view of the results of both approaches, with a special emphasis on the common responses found between the two different stresses, and, within each stress, on the comparison between non-selected ESTs versus subtracted libraries.Acta Horticulturae. 682:247-251. -
Chapter: Global Regulation of Genes in Citrus Fruit in Response to the Postharvest Pathogen Penicillium digitatum
ISBN: 978-1-4020-8929-9 -
Article: Biochemical and molecular characterization of induced resistance against Penicillium digitatum in citrus fruit
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ABSTRACT: To get an insight into the mechanisms underlying resistance of citrus fruit against Penicillium digitatum, we have analyzed at the enzyme activity and gene expression levels the possible involvement of phenylalanine ammonia-lyase (PAL), peroxidase,Postharvest Biology and Technology. 56:31-38. -
Article: Differential tomato transcriptomic responses induced by Pepino mosaic virus isolates with differential aggressiveness
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ABSTRACT: Plant viruses are obligate intracellular parasites that hijack host cellular machinery for replication and movement that generally induce extensive alterations in host gene expression and cell physiology.Plant Physiology. 156(1):301–318. -
Article: Effect of heat-conditioning treatments on quality and phenolic composition of cold stored ‘Fortune’ mandarins
Food Chemistry. 128(4):1080-1086. -
Article: Effect of heat-conditioning treatments on quality and phenolic composition of ‘Fortune’ mandarin fruit
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ABSTRACT: ‘Fortune’ mandarin fruit (hybrid of ‘Dancy’ mandarin × ‘Clementine’ mandarin) are very prone to chilling injury, manifested as pitting and necrosis in the outer part of the peel tissue, and therefore cannot withstand cold quarantine requirements. The aim of this work was to evaluate the effect of high-temperature conditioning on the tolerance of ‘Fortune’ mandarins to cold quarantine and on quality, organoleptic properties and phenolic composition. Fruit were conditioned for 1, 2 or 3 days at 37°C with hot humid air (90-95% RH) and thereafter exposed to a single (16 days at 1.5°C) or a double (32 days at 1.5°C) quarantine treatment, followed by a shelf life period of 4 days at 20°C. The 3 conditioning treatments were effective reducing chilling injury indexes to very low levels and allowed ‘Fortune’ mandarin to withstand not only a single but also a double quarantine treatment. In addition, our results showed that these treatments did not affect either internal fruit quality, as measured by changes in acidity, total soluble solids content and total antioxidant capacity, or fruit firmness and weight loss. Changes in phenolic content and composition of the pulp were studied in fruit conditioned for 1 day at 37°C, which did not alter the organoleptic acceptance of the fruit, and in non-conditioned fruit exposed to the quarantine treatment. More than 40 phenolic compounds, including flavonoids, cinnamic acid derivatives and coumarins, were identified in the pulp of ‘Fortune’ mandarins, hesperidin being the most abundant followed by isorhoifolin, neoponcirin and narirutin. Little differences in phenolic compounds were found between conditioned and non-conditioned fruit stored under low temperature conditions simulating quarantine requirements. Therefore, we can conclude that conditioning the fruit for 1 day at 37°C is a very effective heat-treatment allowing ‘Fortune’ mandarins to withstand quarantine treatments without affecting internal and external fruit quality or the composition and concentration of phenolic compounds relevant for nutrition in citrus fruit.Acta Horticulturae. 877:1333-1340. -
Article: Biochemical and molecular characterization of induced resistance against Penicillium digitatum in citrus fruit
[show abstract] [hide abstract]
ABSTRACT: To get an insight into the mechanisms underlying resistance of citrus fruit against Penicillium digitatum, we have analyzed at the enzyme activity and gene expression levels the possible involvement of phenylalanine ammonia-lyase (PAL), peroxidase, β-1,3-glucanase and chitinase in the flavedo (outer colored part of the fruit peel) and albedo (the inner white part) in elicited fruit. As a tool to induce resistance, we inoculated oranges with P. digitatum and 1 d later fruit were exposed to a hot air treatment at 37 °C for 3 d. All enzyme activities increased in parallel with increased resistance, especially in the albedo, although the highest activities were generally found in the flavedo. Expression of the gene encoding PAL and that of the genes coding for the basic, rather than for the acidic, isoforms of the PR proteins was also induced in both tissues, but most markedly in the albedo.Postharvest Biology and Technology. -
Article: Spatial study of antioxidant enzymes, peroxidase and phenylalanine ammonia-lyase in the citrus fruit–Penicilliumdigitatum interaction
[show abstract] [hide abstract]
ABSTRACT: Changes in the activities of the antioxidant enzymes, superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11) and glutathione reductase (GR; EC 1.6.4.2), as well as in soluble and insoluble peroxidase (POD; EC 1.11.1.7) and in phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) activity and Pal transcript levels in flavedo and albedo tissues of citrus fruit infected with Penicillium digitatum have been examined. Specific probes corresponding to a fragment of the large subunit of the nuclear rRNA from both organisms have been cloned and used to determine the advance of the fungus through the fruit. The activities of all the enzymes were higher in non-infected areas of the flavedo than in the albedo, a fact that may be related to the higher resistance of the flavedo to infection by the pathogen. In both tissues, the activity of the antioxidant enzymes decreased at different rates with the advance of the fungus, except for CAT and soluble POD activities that increased in the area of the flavedo completely colonized by the fungus. On the other hand, the flavedo, but not the albedo, was able to respond to pathogen attack by increasing insoluble POD and PAL activities and Pal transcript levels. However, discrepancies between PAL activity and mRNA levels suggest the ability of P. digitatum to suppress this defense response. Thus, the present study shows that in the interaction between citrus–P. digitatum both host defense responses and pathogen virulence mechanisms are taking place.Postharvest Biology and Technology.
