Climacteric or non-climacteric behavior in melon fruit 2. Linking climacteric pattern and main postharvest disorders and decay in a set of near-isogenic lines
ABSTRACT A set of near-isogenic lines (NILs) of melon (Cucumis melo L.) was used to test the relationship between the climacteric pattern and postharvest disorders at harvest and after 30 days at 8 °C. The NILs contained different chromosome introgressions in the linkage group III from the non-climacteric exotic Korean accession PI 161375 transferred into the genetic background of the non-climacteric Spanish cultivar ‘Piel de Sapo’ (PS). A quantitative trait locus (QTL) in this linkage group induced climacteric behavior in eight NILs accompanied by a peak of ethylene production and fruit dehiscence to different degrees. The cultivar ‘Nicolás’ and one NIL showed a non-climacteric pattern of respiration rate and ethylene production. The climacteric NILs were used to test the relationship between this pattern and postharvest disorders. The reference climacteric lines ‘Fado’ and ‘Védrantais’ were more sensitive to CI and associated Cladosporium rot than the NILs or PS. In general, a more intense climacteric behavior was accompanied by fruit dehiscence, and higher total losses and greater skin scald after storage, than in PS. A higher incidence of chilling injury (CI) in the climacteric NILs was found compared with the non-climacteric ones, although with exceptions (one NIL for CI in the form of scald; the same NIL and one more for pitting). The climacteric onset and netting scald were not related, and CI in the form of skin spots was only found in climacteric NILs and was positively correlated with the maximum peak of ethylene production. Some climacteric NILs did not follow the rule of a higher susceptibility to other disorders and decay after storage compared with PS, such as for example in fruit over-ripening (detected externally or internally), Cladosporium rot at the peduncle and Alternaria rot. Mealiness was independent of climacteric behavior. Three climacteric NILs obtained better flavor scores after storage than PS, although the maximum peak of ethylene production was positively correlated with off-flavor. Genotypic correlation between disorder data and the physiological data of climacteric fruit revealed positive (flavor index) or negative postharvest consequences (skin injuries, rots or off-flavors). At least one QTL can be assigned to most of the quality traits analyzed.
SourceAvailable from: Noelia Dos Santos
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ABSTRACT: Compared to other melon types, oriental sweet melon (Cucumis melo var. makuwa Makino) is quite a different species with a poor shelf-life due to its typical climacteric behaviour, and thin pericarp and rind. In order to investigate the effect of ethanol application on postharvest storage at room temperature (24 °C) and quality of oriental sweet melon, we measured physiological and quality changes induced by ethanol vapor or ethanol injection. Both ethanol treatments significantly inhibited internal ethylene concentrations (IEC), and no ethylene peak occurred when compared with control fruit during storage. However, both ethanol treatments maintained firmness but without significant differences between ethanol-treated and the control melons, except with ethanol injection on day 4. Soluble solids contents were not affected by either treatments. Glucose, fructose and sucrose contents showed a greater increase in ethanol-treated melon flesh and peel tissues than in controls after four days, especially sucrose, the main sugar in melons. Compared with the control, both ethanol treatments resulted in different profiles and composition of aromatic volatile compounds during storage. Both ethanol treatments resulted in a significant increase in ethyl acetate, hexyl acetate and 2-methyl-1-butyle acetate, and a decrease of 2,3-butanediyl diacetate, phenylmethyl acetate and 2-phenethyl acetate. The contents of total esters, including eight newly detected ethyl esters, were 2–4 fold higher in ethanol-treated melons. Ethanol injection more effectively increased accumulation of aroma volatile compounds for a short time, while the effects of ethanol vapor persisted during the storage. Both ethanol treatments increased alcohol acyltransferase (AAT) activity in melon flesh within four days, and levels peaked three days earlier but lower than in the control. There were no significant differences in activities of alcohol dehydrogenase (ADH) and lipoxygenase (LOX) in ethanol-treated and control melons. In summary, postharvest ethanol application reduced the IEC of harvested oriental melons and improved levels of volatile aroma compounds, especially the ethyl esters.Postharvest Biology and Technology 05/2012; 67:75–83. DOI:10.1016/j.postharvbio.2011.12.015 · 2.63 Impact Factor