BackgroundPeach fruit undergoes a rapid softening process that involves a number of metabolic changes. Storing fruit at low temperatures has been widely used to extend its postharvest life. However, this leads to undesired changes, such as mealiness and browning, which affect the quality of the fruit. In this study, a 2-D DIGE approach was designed to screen for differentially accumulated proteins in peach fruit during normal softening as well as under conditions that led to fruit chilling injury.ResultsThe analysis allowed us to identify 43 spots -representing about 18% of the total number analyzed- that show statistically significant changes. Thirty-nine of the proteins could be identified by mass spectrometry. Some of the proteins that changed during postharvest had been related to peach fruit ripening and cold stress in the past. However, we identified other proteins that had not been linked to these processes. A graphical display of the relationship between the differentially accumulated proteins was obtained using pairwise average-linkage cluster analysis and principal component analysis. Proteins such as endopolygalacturonase, catalase, NADP-dependent isocitrate dehydrogenase, pectin methylesterase and dehydrins were found to be very important for distinguishing between healthy and chill injured fruit. A categorization of the differentially accumulated proteins was performed using Gene Ontology annotation. The results showed that the 'response to stress', 'cellular homeostasis', 'metabolism of carbohydrates' and 'amino acid metabolism' biological processes were affected the most during the postharvest.ConclusionsUsing a comparative proteomic approach with 2-D DIGE allowed us to identify proteins that showed stage-specific changes in their accumulation pattern. Several proteins that are related to response to stress, cellular homeostasis, cellular component organization and carbohydrate metabolism were detected as being differentially accumulated. Finally, a significant proportion of the proteins identified had not been associated with softening, cold storage or chilling injury-altered fruit before; thus, comparative proteomics has proven to be a valuable tool for understanding fruit softening and postharvest.

Artículo de publicación ISIPeach and nectarine quality traits such as flavor, texture, and juiciness are important for consumer acceptance. Maturity date (MD) also plays a role in the fruit-ripening process and is an important factor for marketing fresh fruit. On the other hand, cold storage produces a physiological disorder known as chilling injury where the most important symptom is a lack of juice in the flesh or mealiness (M). In this study, we analyzed an F2 population obtained from a self-pollination of "Venus" nectarine that segregates for MD and M. We built a linkage map with 1,830 SNPs, 7 SSRs and two slow-ripening (SR) morphological markers, spanning 389.2 cM distributed over eight linkage groups (LGs). The SR trait was mapped to LG4 and we compared the whole genome sequences of a SR individual and "Venus" and identified a deletion of 26.6 kb containing ppa008301m (ANAC072) co-localized with the SR trait. Three Quantitative Trait Loci (QTL) for MD were detected; they all co-localize on LG4 between 31.0 and 42.0 cM. Four co-localizing QTLs on LG4 between 33.3 and 40.3 cM were detected for M, explaining 34 % of the phenotypic variation. We identified five and nine candidate genes (CGs) for MD and M from the QTL regions, respectively. Our results suggest that the transcription factors (TFs) ANAC072 and ppa010982m (ERF4) are CGs for both traits. LG4 contains a cluster for genetic factors that possibly regulate MandMD, but functional validation is necessary to unravel the complexity of genetic control responsible for fruit traits.Conicyt-Fondecyt 11121396 Conicyt-FONDEF G13i10005 Corfo-Innova 09PMG-7240 Fondo de Areas Prioritarias Centro de Regulacion del Genoma 15090007 UNAB DI-489-14R CONICYT D-21090737 PFB-1

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Cutting leaves of Romaine lettuce (Lactuca sativa L. cv. Longifolia) produces a wound signal that induces the synthesis of phenylalanine ammonia lyase (PAL, EC 4.3.1.5) and the accumulation of phenolic compounds in cells up to 2 cm from the site of injury, and tissue browning near the site of injury. The response of leaves within a head of Romaine lettuce to putative chemical wound signals [abscisic acid (ABA), jasmonate (JA) and methyl jasmonate (MeJA)] differed significantly with leaf age. Exposure of harvested heads of lettuce to ABA, JA, MeJA, or salicylic acid (SA) did not induce changes in PAL activity, the concentration of phenolic compounds or browning in mature leaf tissue that was similar to the level induced by wounding. Methyl jasmonate applied as vapour (10, 100 or 1000 &mgr;l kg-1 FW), or as an aqueous spray or dip (0.01-100 &mgr;M) at 5 or 10 degrees C did not produce an effect on PAL activity or browning that differed significantly from the untreated controls. In contrast, JA, MeJA and SA did induce elevated levels of PAL activity in younger leaves. However, the levels induced were far lower than those induced by wounding. Wound induced phenolic metabolism in mature leaves appears to be induced by different signals than those functioning in young leaves.