Oxidative Stress Associated with Chilling Injury in Immature Fruit: Postharvest Technological and Biotechnological Solutions

Immature, vegetable-like fruits are produced by crops of great economic importance, including cucumbers, zucchini, eggplants and bell peppers, among others. Because of their high respiration rates, associated with high rates of dehydration and metabolism, and their susceptibility to chilling injury (CI), vegetable fruits are highly perishable commodities, requiring particular storage conditions to avoid postharvest losses. This review focuses on the oxidative stress that affects the postharvest quality of vegetable fruits under chilling storage. We define the physiological and biochemical factors that are associated with the oxidative stress and the development of CI symptoms in these commodities, and discuss the different physical, chemical and biotechnological approaches that have been proposed to reduce oxidative stress while enhancing the chilling tolerance of vegetable fruits

Genetic and Pre- and Postharvest Factors Influencing the Content of Antioxidants in Cucurbit Crops

Cucurbitaceae is one of the most economically important plant families, and includes some worldwide cultivated species like cucumber, melons, and squashes, and some regionally cultivated and feral species that contribute to the human diet. For centuries, cucurbits have been appreciated because of their nutritional value and, in traditional medicine, because of their ability to alleviate certain ailments. Several studies have demonstrated the remarkable contents of valuable compounds in cucurbits, including antioxidants such as polyphenols, flavonoids, and carotenoids, but also tannins and terpenoids, which are abundant. This antioxidant power is beneficial for human health, but also in facing plant diseases and abiotic stresses. This review brings together data on the antioxidant properties of cucurbit species, addressing the genetic and pre- and postharvest factors that regulate the antioxidant content in different plant organs. Environmental conditions, management, storage, and pre- and postharvest treatments influencing the biosynthesis and activity of antioxidants, together with the biodiversity of this family, are determinant in improving the antioxidant potential of this group of species. Plant breeding, as well as the development of innovative biotechnological approaches, is also leading to new possibilities for exploiting cucurbits as functional products

Effect of Ethylene-Insensitive Mutation etr2b on Postharvest Chilling Injury in Zucchini Fruit

Zucchini is a vegetable fruit that is very susceptible to postharvest chilling injury, and fruit ethylene production is correlated with chilling injury sensitivity, such that the more tolerant the cultivar, the lower is its ethylene production. It is expected that zucchini fruit with reduced sensitivity to ethylene would have a higher chilling injury tolerance. In this study, we compared the postharvest fruit quality of wild type and ethylene-insensitive mutant etr2b, in which a mutation was identified in the coding region of the ethylene receptor gene CpETR2B. Flowers from homozygous WT (wt/wt), mutant plants in homozygous (etr2b/etr2b) and heterozygous (wt/etr2b) were hand-pollinated, and all fruits were harvested with the same length, at about 8 days after pollination. After harvesting, fruit of each genotype was randomly divided in 3 batches of 12 fruits each (four replications with three fruits each), and then stored at 4 °C and 95% RH. At 0, 7, and 14 days after cold storage, each batch was used to assess ethylene production, respiration rate, weight and firmness loss, chilling injury, and oxidative stress metabolites. The results showed a lower chilling injury associated with lower cold-induced ethylene production in the mutant fruit, in comparison with the WT fruit. These data demonstrated that the ethylene-insensitive etr2b mutant fruit was more tolerant to chilling injury, confirming that basal ethylene in the still undamaged fruit could function as a modulator of post-harvest chilling injury. Moreover, the higher chilling tolerance of the etr2b mutant fruit was not associated with MDA content, but was concomitant with a reduction in the accumulation of hydrogen peroxide in the refrigerated mutant fruit

Evaluation of ethylene production by ten Mediterranean carnation cultivars and their response to ethylene exposure

Vase life is one of the most important characters of postharvest cut flower quality. The onset of ethylene production and the amount of ethylene produced by flowers vary with the carnation cultivar, and thus influence their vase life. In the present study, differences in ethylene production and the response to exogenous ethylene among carnation cultivars were evaluated. Ten different cultivars: �Baltico�, �Domingo�, �Exotica�, �Famosa�, �Kiro�, �Madame Augier�, �Master�, �Mundo�, Pilar� and �Reina�were studied. Five flowers for each cultivar were exposed for 8 hours to 1 ìL L�1 exogenous ethylene concentration. Ethylene production, fresh weight and water uptake was measured daily throughout the experiments. The 10 different cultivars studied showed clear differences in vase life, ethylene production, onset time in ethylene production and response to exogenous ethylene. The shortest vase life was for �Exotica� flowers which was only 11.6 days, while �Baltico� and �Pilar� lasted 2.5-3 times longer than �Exotica�. Most of the investigated cultivars showed notable increases in the amount of ethylene. However, �Baltico� and �Pilar� flowers produced only a trace amount of ethylene and had the longest vase life. Results showed that cultivars with a long vase life (�Baltico� and �Pilar�) display high ethylene responsiveness and, in contrast, cultivars with a short vase life (�Exotica� and �Mundo�) present low responsiveness. The decline in fresh weight of cut flowers observed in the last phase of their vase life occurred earlier in short-lived cultivars than in the longer-lived ones.La vida util de la flor cortada es uno de los caracteres mas importantes de evaluacion de la calidad en poscosecha. El momento y cantidad de etileno producido por la flor de clavel varia entre cultivares y eso influye en la vida util de la flor. El objetivo de este trabajo fue evaluar diferencias en la produccion de etileno y su repuesta al etileno exogeno en diez cultivares de clavel (�eBaltico�f, �eDomingo�f, �eExotica�f, �eFamosa�f, �eKiro�f, �eMadame Augier�f, �eMaster�f, �eMundo�f, Pilar�f y �eReina�f). Se expusieron durante 8 h cinco flores de cada cultivar a una concentracion de 1 �ÊL L.1 de etileno exogeno. Se midio la produccion de etileno, peso fresco y absorcion de agua diariamente. Los 10 cultivares estudiados presentaron diferencias claras en la vida util de la flor, tiempo y produccion de etileno y respuesta al etileno. �eExotica�f fue el cultivar con vida util mas corta (11,6 dias), mientras �eBaltico�f y �ePilar�f presentaron una vida util 2,5- 3 veces mayor que �eExotica�f. La mayoria de los cultivares produjeron una notable cantidad de etileno, sin embargo �eBaltico�f y �ePilar�f, con la vida util mas larga, produjeron solo cantidades trazas de etileno. Estos cultivares de vida util larga (�eBaltico�f y �ePilar�f) mostraron alta sensibilidad al etileno, sin embargo, los de vida util corta (�eExotica�f y �eMundo�f) presentaron baja sensibilidad. La reduccion del peso fresco observado en la primera fase de la vida util de la flor, ocurre antes en los cultivares con una vida util corta que larga