Irasema Vargas-Arispuro

Effect of infiltrated polyamines on polygalacturonase activity and chilling injury responses in zucchini squash (Cucurbita pepo L.).

The effect of exogenous polyamines on electrolyte leakage, chilling index, polygalacturonase activity (PG), ethylene production, and firmness in zucchini squash fruits stored for 12 days at 2 degrees C or 10 degrees C, 85-90% RH was evaluated. Fruits were infiltrated with putrescine (PUT) spermidine (SPD) and spermine (SPM) at 0.1, 0.25, 0.5, 2.0, and 4.0 mM. All polyamines exerted a protective effect on cell and organelle membranes. The most effective was SPD, which reduced electrolyte leakage between 62% and 82%, compared to control fruits stored at 2 degrees C. At 10 degrees C they did not exhibit chilling injury (CI) symptoms, while at 2 degrees C SPM (0.5 mM) and SPD (0.5 mM) diminished them 92% and 100%, respectively; which extended storage life for 8-10 days at 2 degrees C. High concentrations of polyamines (>2.0 mM) caused the appearance of CI symptoms. PG activity diminished proportionally to the concentration of polyamine except for the concentration at 4.0 mM. No significant changes were observed in ethylene production.

Plant Cell Wall Polymers: Function, Structure and Biological Activity of Their Derivatives

© 2012 Martinez-Tellez et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Plant Cell Wall Polymers: Function, Structure and Biological Activity of Their Derivatives

Irreversibility of chilling injury in zucchini squash (Cucurbita pepo L.) could be a programmed event long before the visible symptoms are evident

Zucchini fruits were subjected to 2.5 or 10 degrees C for 16d, followed by transfer to 20 degrees C for 24h in order to evaluate the relationship between ripening pattern, measured as CO(2) evolution and ethylene (C(2)H(4)) production, and metabolic heat production (q). Chilling injury (CI) visible symptoms were evident after 8d at 2.5 degrees C, but none were recorded on fruits kept at 10 degrees C. In fruits held at 10 degrees C, q, C(2)H(4) production, and CO(2) evolution diminished in the course of 16d, whereas in those at 2.5 degrees C CO(2) evolution showed an early burst peaking at 8d. Both C(2)H(4) production and q also showed a burst at 2.5 degrees C but they started at 4 and 8d, respectively, and peaked at 12d. The results showed that irreversibility of chilling injury in zucchini could occur long before the appearance of visible symptoms, although the metabolic activity accompanying the irreversibility process was not noticeable by isothermal calorimetry.

Compounds Derived from Garlic as Bud Induction Agents in Organic Farming of Table Grape

A B S T R A C T Viticulture is one of the most important economic activities in the Northwest of Mexico. A major obstacle for the economic production is the insufficient period of chilling temperatures. This problem leads to poor budbreak, which in turn results in reduced yields. This problem is aggravated when plants are cultivated using the organic farming system, mostly because there are not organically approved restbreaking agents. In this work different products derived from garlic (Allium sativum L.) were obtained and evaluated as stimulate budbreak agent of table grape (Vitis vinifera L.) cvs. Flame Seedless and Perlette. The isolated compounds were chemically identified and include allicin, diallyl disulfide, diallyl trisulfide, 3-vynil-[4H]1.2-ditiin and 2-vynil-[3H]-1.3-ditiin, S-methyl cysteine sulphoxide, dimethyl disulfide, dimethyl trisulfide and dimethyl thiosulfonate. Cuttings with six buds were used to evaluate the compounds. After compounds were applied, the cuttings were transferred to a growing chamber at 24 °C. All evaluated compounds promoted budbreak in the cuttings of Flame Seedless and Perlette. The volatile compounds from S-methyl cysteine sulfoxide promoted 100% of budbreak of both cultivars. The compounds from garlic that stimulated budbreak in grapevines in this work include sulphur in their molecule; therefore we propose that sulphur could play a key role in breaking bud dormancy of grape cultivars evaluated in this study.

Pectin-derived oligosaccharides increase color and anthocyanin content in Flame Seedless grapes

BACKGROUND Grapes grown in warm weather do not develop a desirable red color and require the use of products to enhance berry color. Pectin-derived oligosaccharides (PDOs) have been shown to have a role in various responses including plant defense, growth and development. In this work a mixture of PDOs with 3-20 degrees of polymerization was applied to Vitis vinifera cv. Flame Seedless grapes under field conditions and compared to the effects of ethephon (an ethylene-releasing compound). The effect of treatments on grape color, anthocyanin content and phenylalanine ammonia lyase (PAL) mRNA levels was evaluated. RESULTS PDOs treatment increased berry color measured by the Color Index of Red Grapes (CIRG) and anthocyanin content, compared to ethephon and untreated berries (control); 1.5, 1 and 0.5 mg mL⁻¹ PDOs increased berry color by 30%, 27% and 26%, respectively, when compared to control berries. Levels of PAL mRNA accumulating in berries treated with PDOs were elevated within the first 24 h of treatment. CONCLUSIONS PDOs enhanced the color and anthocyanin content of Flame Seedless grape berries possibly due by the induction of PAL mRNA expression. The results demonstrated that PDOs can be used to improve fruit quality aspects such as berry skin color.

Combination of Cymbopogon citratus with Allium cepa essential oils increased antibacterial activity in leafy vegetables

BACKGROUND Cymbopogon citratus and Allium cepa essential oils (EOs) are rich in terpenes and sulfur compounds respectively, both with antibacterial activity and different cell targets, supporting the idea that their combination can increase their efficacy. RESULTS Major constituents of C. citratus were geranial and neral, while A. cepa presented dipropyl disulfide and dipropyl trisulfide. Cymbopogon citratus and A. cepa EOs inhibited the in vitro growth of Escherichia coli O157:H7 (minimal inhibitory concentrations of 2.21 and 5.13 g L-1 respectively), Salmonella Choleraesuis (3.04 and 1.28 g L-1 ), Listeria monocytogenes (1.33 and 2.56 g L-1 ) and Staphylococcus aureus (0.44 and 5.26 g L-1 ). Application of the EO combination to spinach caused a greater reduction in E. coli (2.34 log colony-forming units (CFU) g-1 ), S. Choleraesuis (2.94 log CFU g-1 ), L. monocytogenes (2.06 log CFU g-1 ) and S. aureus (1.37 log CFU g-1 ) compared with higher doses of individual EOs; a similar effect was observed for romaine lettuce. Individual and combined EOs caused a reduction in flavor acceptability level; however, no significant differences were found among odor acceptability of control vegetables and those treated with the EO combination and C. citratus EO. CONCLUSION Leafy vegetables treated with the EO combination showed higher antibacterial protection and odor acceptability compared with individual EO treatments.

Post-harvest control of gray mold in table grapes using volatile sulfur compounds from Allium sativum.

BACKGROUND This study proposes the use of volatile sulfur compounds derived from garlic (Allium sativum) extracts applied via gas for the control of Botrytis cinerea, which causes post-harvest disease in table grapes. The effects of the volatile compounds emitted by garlic extract and sodium metabisulfite on conidia germination of B. cinerea were evaluated in vitro to assess their effectiveness at controlling grey mold on grapes stored at different temperatures. RESULTS Diallyl disulfide, diallyl trisulfide and allicin were identified and quantified in a garlic extract using reversed-phase high-performance liquid chromatography. The volatile compounds emitted by the garlic extract in the form of allicin and diallyl trisulfide inhibited conidia germination of B. cinerea in vitro and significantly reduced the lesion diameters on stored grapes, which were similar to the effects of sodium metabisulfite, while the diallyl disulfide did not have any effect. The sulfhydryl groups of cysteine or reduced glutathione completely reversed the antifungal effect of these compounds. CONCLUSION The antifungal activity that allicin and diallyl trisulfide, which are the volatile compounds emitted by a garlic extract, exerted on conidia germination of B. cinerea may be considered as an alternative for the control of gray mold in table grapes after harvest.

Volatiles emitted by Carya illinoinensis (Wang.) K. Koch as a prelude for semiochemical investigations to focus on Acrobasis nuxvorella Nuenzig (Lepidoptera: Pyralidae).

BACKGROUND Plant volatiles have complex intra- and interspecific effects in the environment that include plant/herbivore interactions. Identifying the quantity and quality of volatiles produced by a plant is needed to aid the process of determining which chemicals are exerting what effects and then examining whether these effects can be manipulated to benefit society. The qualitative characterization of volatile compounds emitted by pecan, Carya illinoinensis (Wang.) K. Koch, was begun in order to establish a database for investigating how these volatiles affect Acrobasis nuxvorella Nuenzig, a monophagous pest of pecan. Headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was used for the analysis of the volatile constituents of pecan during three phenological stages (dormant buds, intact new shoot growth and intact nutlets) of the Western Schley and Wichita cultivars. RESULTS About 111 distinct compounds were identified from the two cultivars, accounting for ∼99% of the headspace volatiles. The chromatographic profiles of both varieties revealed variations in the volatile composition and proportion between cultivars, with a predominance of terpene hydrocarbons, of the sesquiterpenes class, as well as monoterpenes. CONCLUSION The significantly higher responsiveness recorded for the larvae of A. nuxvorella to C. illinoinensis shoots indicates that the larvae may be activated by terpenes emanating from the new shoot growth. This is the first study that has examined volatiles of pecan in Mexico.

Pectic and Galacturonic Acid Oligosaccharides on the Postharvest Performance of Citrus Fruits

Araceli M. Vera-Guzman is a doctoral student in the graduate program of CIAD, and received a graduate fellowship from CONACyT, Mexico. Part of this work was supported by the Spanish Ministry of Science and Technology (Research Grant AGL2013-41734-R and AGL2014-55802-R) and by the Generalitat Valenciana, Spain (Grant PROMETEOII/2014/027).

Data on antioxidant activity in grapevine (Vitis vinifera L.) following cryopreservation by vitrification.

Cryopreservation is used for the long-term conservation of plant genetic resources. This technique very often induces lethal injury or tissue damage. In this study, we measured indicators of viability and cell damage following cryopreservation and vitrification-cryopreservation in Vitis vinifera L. axillary buds cv. “Flame seedless” stored in liquid nitrogen (LN) for: three seconds, one hour, one day, one week and one month; after LN thawed at 38 °C for three minutes. The enzymatic activity of catalase (CAT) and superoxide dismutase (SOD), as well as the amount of malondialdehyde (MDA), total protein and viability were assayed.