Aktivnost β-galaktozidaze i poligalakturonaze u kaši od tikvica (Cucurbita pepo L.) uskladištenoj pri niskim temperaturama

When fruits are exposed to chilling temperatures, enzymatic systems are affected and normal cell metabolism is altered; cell wall enzymes are the least studied in this respect. Our objective is to determine the effect of storage temperature and/or kind of tissue on the activity of the enzymes polygalacturonase (PG) and β-galactosidase (β-gal) in zucchini squash (Cucurbita pepo L.) subjected to 2.5 and/or 12 °C for 16 days. Exocarp and endocarp samples were analyzed every 4 days for PG and β-gal activities. The highest β-gal activity was found in the exocarp at 12 °C; in both tissues β-gal decreased with time at 2.5 °C, but increased at 12 °C. PG activity was higher in the endocarp (highest activity at 2.5 °C) than in the exocarp (highest activity at 12 °C). It was concluded that PG activity in the exocarp constitutes an adequate system for studying the relationship between chilling injury and cell wall biological activity.U plodovima izloženim niskim temperaturama mijenja se enzimska aktivnost što utječe na metabolizam stanica. Najmanje je istražen utjecaj niskih temperatura na enzime stanične stijenke. Istraživanje je provedeno da bi se ustanovio učinak temperature skladištenja na aktivnost enzima poligalakturonaze i β-galaktozidaze u kaši tikvica (Cucurbita pepo L.) tijekom 16 dana pri temperaturi od 2,5 ili 12 °C. Svaki četvrti dan u uzorcima egzokarpa i endokarpa ispitivana je aktivnost poligalakturonaze i β-galaktozidaze. Najveća aktivnost β-galaktozidaze pronađena je u uzorku egzokarpa pri 12 °C. U oba se tkiva aktivnost β-galaktozidaze smanjivala s vremenom pri temperaturi od 2,5 °C, a povećala pri 12 °C. Veća aktivnost poligalakturonaze bila je u endokarpu (najveća pri 2,5 °C) nego u egzokarpu (najveća aktivnost pri 12 °C). Zaključeno je da se praćenjem aktivnosti poligalakturonaze u egzokarpu može utvrditi odnos između oštećenja nastalih pri niskim temperaturama i biološke aktivnosti stanične stijenke

Aktivnost β-galaktozidaze i poligalakturonaze u kaši od tikvica (Cucurbita pepo L.) uskladištenoj pri niskim temperaturama

When fruits are exposed to chilling temperatures, enzymatic systems are affected and normal cell metabolism is altered; cell wall enzymes are the least studied in this respect. Our objective is to determine the effect of storage temperature and/or kind of tissue on the activity of the enzymes polygalacturonase (PG) and β-galactosidase (β-gal) in zucchini squash (Cucurbita pepo L.) subjected to 2.5 and/or 12 °C for 16 days. Exocarp and endocarp samples were analyzed every 4 days for PG and β-gal activities. The highest β-gal activity was found in the exocarp at 12 °C; in both tissues β-gal decreased with time at 2.5 °C, but increased at 12 °C. PG activity was higher in the endocarp (highest activity at 2.5 °C) than in the exocarp (highest activity at 12 °C). It was concluded that PG activity in the exocarp constitutes an adequate system for studying the relationship between chilling injury and cell wall biological activity.U plodovima izloženim niskim temperaturama mijenja se enzimska aktivnost što utječe na metabolizam stanica. Najmanje je istražen utjecaj niskih temperatura na enzime stanične stijenke. Istraživanje je provedeno da bi se ustanovio učinak temperature skladištenja na aktivnost enzima poligalakturonaze i β-galaktozidaze u kaši tikvica (Cucurbita pepo L.) tijekom 16 dana pri temperaturi od 2,5 ili 12 °C. Svaki četvrti dan u uzorcima egzokarpa i endokarpa ispitivana je aktivnost poligalakturonaze i β-galaktozidaze. Najveća aktivnost β-galaktozidaze pronađena je u uzorku egzokarpa pri 12 °C. U oba se tkiva aktivnost β-galaktozidaze smanjivala s vremenom pri temperaturi od 2,5 °C, a povećala pri 12 °C. Veća aktivnost poligalakturonaze bila je u endokarpu (najveća pri 2,5 °C) nego u egzokarpu (najveća aktivnost pri 12 °C). Zaključeno je da se praćenjem aktivnosti poligalakturonaze u egzokarpu može utvrditi odnos između oštećenja nastalih pri niskim temperaturama i biološke aktivnosti stanične stijenke

Total RNA quality of lyophilized and cryopreserved dormant grapevine buds

Background: Plant tissues must be preserved in their collection state, especially for genome-wide expression profile studies. Lyophilization is a feasible, affordable tool when fresh tissues cannot be shipped at ultralow temperatures from their origin to the place of analysis. In this study, the total RNA quality of dormant grapevine buds ( Vitis vinifera L. cv. \u2018Flame Seedless\u2019) of freeze-dried samples stored at room temperature conditions was evaluated and compared to that of cryopreserved (-80\ub0C) grapevine buds. Results: Good yield and quality of RNA were obtained from freeze-dried dormant buds stored at room temperature for 0, 3 and 6 weeks after they were lyophilized. Further experiments confirmed that the extracted total RNA could be used for actin and \u3b2-tubulin PCR gene amplification. Conclusion: High-quality RNA that is useful for downstream applications was obtained from freeze-dried dormant grapevine bud tissue, similarly to the RNA obtained from cryopreserved dormant grapevine buds

Compuestos Derivados de Ajo Como Agentes Inductores de Brotación en Cultivo Orgánico de Uva de Mesa

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.La viticultura es una de las principales actividades económicas en el Noroeste de México. Entre los problemas que enfrenta esta actividad está el período de frío insuficiente, lo que lleva a una pobre brotación y consecuentemente una menor producción. Este problema se agrava cuando se cultivan plantas por el método orgánico, ya que no existen agentes inductores de brotación aprobados para uso orgánico. En este trabajo se aislaron diferentes compuestos derivados de ajo ( Allium sativum L.) que se evaluaron para medir su efecto en la inducción de brotación de yemas de vid ( Vitis vinifera L.) de los cultivares Flame Seedless y Perlette. Los compuestos aislados de ajo e identificados químicamente fueron: allicina, dialil disulfuro, dialil trisulfuro, 3-vinil-(4H)-1,2-ditiin y 2-vinil-(3H)-1,3-ditiin, S-metilcisteína sulfóxido, dimetil disulfuro, dimetil trisulfuro y dimetil tiosulfonato. Se utilizaron estacas de seis yemas para la evaluación de los compuestos; después de la aplicación las estacas se desarrollaron en cámara de crecimiento a 24 °C. Todos los compuestos evaluados promovieron la brotación de las yemas de ambos cultivares. Los compuestos volátiles de S-metilcisteína sulfóxido indujeron 100% de brotación. Los compuestos derivados de ajo que indujeron la brotación en este trabajo contienen sulpher en su molécula, por lo que se deduce que el sulpher puede tener un importante papel en el rompimiento de la dormancia de las yemas de vid de los cultivares evaluados en este estudio

Activity of β-Galactosidase and Polygalacturonase in Zucchini Squash (Cucurbita pepo L.) Stored at Low Temperatures

When fruits are exposed to chilling temperatures, enzymatic systems are affected and normal cell metabolism is altered; cell wall enzymes are the least studied in this respect. Our objective is to determine the effect of storage temperature and/or kind of tissue on the activity of the enzymes polygalacturonase (PG) and β-galactosidase (β-gal) in zucchini squash (Cucurbita pepo L.) subjected to 2.5 and/or 12 °C for 16 days. Exocarp and endocarp samples were analyzed every 4 days for PG and β-gal activities. The highest β-gal activity was found in the exocarp at 12 °C; in both tissues β-gal decreased with time at 2.5 °C, but increased at 12 °C. PG activity was higher in the endocarp (highest activity at 2.5 °C) than in the exocarp (highest activity at 12 °C). It was concluded that PG activity in the exocarp constitutes an adequate system for studying the relationship between chilling injury and cell wall biological activity

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

Orange [Citrus sinensis (L.) Osbeck] and grapefruit (Citrus paradisi Macfad) citrus fruits are prone to develop different peel physiological disorders caused by storage at both chilling and nonchilling temperatures. The effect of galacturonic acid oligosaccharides (GAOs) and pectic oligosaccharides (POs) in reducing postharvest nonchilling peel pitting (NCPP), decay, and chilling injury (CI) in orange cv. Navelina and the effect of POs in reducing CI in grapefruit cv. Rio Red, were investigated. The incidence of these disorders was examined in fruits stored at chilling and nonchilling temperatures and at 90% to 95% relative humidity (RH). POs showed a better efficacy than GAOs in reducing postharvest losses in orange. The POs were able to reduce NCPP and decay in ‘Navelina’ fruits stored at 20 °C, irrespective of the fruit maturity stage. The application of 10 g·L−1 POs also reduced CI and the chilling-induced ethylene production in oranges and grapefruits maintained at the chilling temperature. Likewise, the decrease in ethylene production found in ‘Navelina’ fruits that developed NCPP during storage at the nonchilling temperature was related to lower peel damage. Moreover, results showed that POs do not induce an increase in ethylene when fruit are stored under conditions that do not cause stress-related injury to fruit. Therefore, POs efficacy in reducing postharvest physiological disorders is not likely mediated by ethylene. Overall results indicate that the application of POs may be an acceptable alternative to mitigate postharvest losses of citrus fruits.Araceli M. Vera-Guzman is a doctoral student in the graduate program of CIAD, and received a graduate fellowship from CONACyT, México. 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).Peer reviewe