117,934 research outputs found
Flavonoid metabolism and gene expression in developing olive (Olea europaea L.) fruit.
No full textThe expression pattern of six genes (phenylalanine-ammonia-lyase, PAL, chalcone synthase, CHS, flavanone 3-hydroxylase, F3H, dihydroflavonol 4-reductase, DFR, anthocyanidin synthase, ANS, UDP-glucose-flavonoid 3-O-glucosyltransferase, UFGT) was studied, together with the accumulation of total flavonoids and anthocyanins in developing olive (Olea europaea L.) fruit. Flavonoid concentration showed the highest values in young fruit whereas anthocyanins accumulated at ripening, in particular in epicarp tissue, concurrently with an up-regulation of UFGT. PAL, CHS, F3H, and UFGT were expressed at the early stages of fruit development when DFR and ANS transcripts were not detected. DFR was induced in the epicarp at the onset of ripening and color change, while ANS transcripts were extremely abundant at a more advanced stage. A coordinated up-regulation of the genes involved in the last steps of anthocyanin biosynthesis was observed in ripe olives. These results suggest that DFR and ANS, together with UFGT, might represent key elements in the regulation of anthocyanin biosynthesis in olives, and that the expression pattern of these two genes could be used to monitor, at the molecular level, the evolution of ripening in fruits of this species
Phenol compound metabolism and gene expression in the skin of wine grape (Vitis vinifera L.) berries subjected to partial postharvest dehydration
No full textSpecific polyphenol compound concentrations and gene expression patterns were determined by both microarray and qRT-PCR analyses in the epicarp of red-skinned grape berries (Vitis vinifera L. cv ‘Raboso
Piave’) dehydrated, after harvest, at slow (S) and rapid (R) rates of up to 10 and 30% weight loss (WL). Increases in flavonols (quercetin) and trans-resveratrol concentrations were observed in the skins of all
dehydrated samples, whereas flavan-3-ols concentrations showed a decreasing trend, which was more pronounced in S samples. The decrease in flavan-3-ol concentrations was paralleled by a reduction in
procyanidin B1 and, particularly B2. Computational analysis of microarray data revealed that several key genes of the flavonoid pathways were unaffected or down-regulated during berry ehydration, with the exception of flavonol synthase, which was induced as well as one MybB transcription factor. Chalcone
synthase (CHS), flavanone 3-hydroxylase (F3H), leucoanthocyanidin dioxygenase (LDOX) and MybA
were markedly down-regulated, particularly in relation to 30% WL, whereas UDP-glucose:flavonoid 3-Oglucosyltransferase
(UFGT) was unaffected in all the samples considered. Specific genes involved in the lignin biosynthetic pathway, including laccase, were induced in the most dehydrated samples. Considering
the accumulation pattern and gene expression profiles, stilbenes and flavonols may represent useful biomarkers to monitor postharvest dehydration
The expression of cellulase gene family members during induced avocado fruit abscission and ripening
No full textOxygen concentration and ethylene production in roots and leaves of wheat - Short-term reaction in air after anoxic and hypoxic treatments
No full textSeven-day old wheat seedlings (Triticum aestivum L. cv. MEC) were incubated in small jars, fluxed with gas mixtures of nitrogen-oxygen (oxygen concentrations 0, 0.3, 1, 2.5, 10%) for up to 48 h. Effects of anoxia and hypoxia on ethylene evolution and ethylene-forming enzyme (EFE) activity were determined 1 h after the plants had been transferred to air, respectively. 1-aminocyclopropane-1-carboxylic acid (ACC) content was measured immediately after treatments. Results showed that the ethylene production is differently affected by oxygen deprivation in roots and leaves. The effects are more closely related to ACC accumulation than to the EFE activity. In leaves, ethylene evolution is almost unaffected by oxygen concentrations above ca 1%
Effects of Postharvest Partial Dehydration and Prolonged Treatments with Ethylene on Transcript Profiling in Skins of Wine Grape Berries.
No full textor certain food products, postharvest controlled stresses or treatments with specific elicitors are applied to induce desired physical/chemical changes and/or to positively affect phytochemical content. This is the case of wine grapes where both strategies, singularly applied or coupled, can be used to modulate berry composition and, as a consequence, affect wine quality traits. Since the knowledge of the effects of these postharvest treatments on berry metabolism and the regulation of gene expression is very limited, a large-scale transcriptome analysis has been carried out, using an oligo-based microarray (14,562 probes) on skins of wine grape (Vitis vinifera L.) berries subjected to dehydration, at different rates, up to 30% of weight loss or to ethylene treatment (500 ppm for 7 days) after harvest. A number of differentially expressed targets was detected following both treatments, indicating that grape berries are still reactive at advanced stages of postharvest dehydration and that ethylene induces marked changes in transcriptome after harvest also in non-climacteric fruit such as grape berries
Molecular and metabolic analyses in developing olive fruit in relation to different water regimes.
No full textEndo-β-1,4-glucanases are involved in peach fruit growth and ripening, and regulated by ethylene
No full textDuring peach (Prunus persica [L.] Batsch) fruit development and ripening the cell wall undergoes several structural and biochemical changes driven by several hydrolases. Among these, the endo-beta-1.4-D-glucanase (EGase, EC 3.2.1.4), or cellulase, may play a crucial role. Involvement of EGase throughout development and ripening of the fruit of cv. Redhaven was assessed by monitoring enzyme activity, specific polypeptide accumulation and gene transcription. During the four stages of growth EGase activity was high during S1 and in the early S2, declined during S3, and increased with the onset of ripening (S4). Two isoforms with isolectric points of 6.5 and 9.5 were identified. The pI 6.5 EGase was the only form present during the early stages of growth, whereas the pi 9.5 EGase was most abundant during ripening. The same isoforms were present in leaf and fruit abscission zones. The antibody raised against the pi 9.5 EGase, purified from lear abscission zones, cross-reacted with a protein of 54 kDa. A cDNA clone of 753 bp encoding peach EGase was obtained by RT-PCR. EGase transcripts, detectable only after amplification of total RNA by RT-PCR, were observed during S1, and at the preclimacteric and climacteric stages. However, the strongest hybridisation occurred at ripening, in correspondence with the maximal enzyme activity and polypeptide accumulation, which took place before the ethylene climacteric and in the early stage of flesh softening. Propylene treatments reduced EGase activity during the early stage of fruit growth but dramatically enhanced enzyme activity and the related transcript accumulation at ripening, and accelerated the loss of firmness. In fruit treated with 2,5-norbornadiene the softening process was strongly inhibited and the rise in EGase transcripts and activity did not take place. The results point to the EGases being involved in early fruit growth and the initial phases of softening. The presence of two isoforms and the dual effect of propylene on enzyme activity suggest that different EGase genes operate during the early and late developmental stages in peach fruit
- …
