Role of Calcium and Chelating Agents in Regulating the Degradation of Tomato Fruit Tissue by Polygalacturonase

Buescher, R. W.; Hobson, Graeme E.

doi:10.1111/j.1745-4514.1982.tb00682.x

Cited by 53 publications

(40 citation statements)

References 33 publications

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“…One possibility is that the biochemical milieu of the tobacco cell wall is incompatible with polygalacturonase activity. For instance, high calcium levels, if present in the cell wall, would inhibit polygalacturonase activity (Buescher and Hobson, 1982). Another possibility is that although the enzyme appears to be secreted to the cell wall, it may not be accessible to its polyuronide substrate because of improper targeting within the cell wall.…”

Section: Discussionmentioning

confidence: 99%

Analysis of tomato polygalacturonase expression in transgenic tobacco.

et al. 1990

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Tomato polygalacturonase is a cell wall enzyme secreted in large amounts during tomato fruit ripening. Polygalacturonase is synthesized as a glycoprotein precursor that undergoes numerous cotranslational and post-translational processing steps during its maturation, yielding three isozymes in tomato fruit, PG1, PGPA, and PGPB. To investigate the physiological roles of the three isozymes and the functional significance of the polygalacturonase processing domains in its intracellular transport and activity, we have examined polygalacturonase expression in transgenic tobacco plants. A full-length polygalacturonase cDNA was placed under control of the cauliflower mosaic virus 35s promoter and introduced into tobacco by way of Agrobacterium-mediated transformation. Analysis of transgenic tobacco plants indicated that (1) immunologically detectable polygalacturonase can be extracted from leaves, roots, and stems of transgenic tobacco plants; ( 2 ) only PGSA and PGPB were detectable in transgenic tobacco; (3) the polygalacturonase isozymes present in transgenic tobacco were electrophoretically indistinguishable from the tomato isozymes; (4) the N-terminal sequence, degree of N-linked glycosylation, and extent of oligosaccharide processing were similar in polygalacturonase from transgenic tobacco and tomato; (5) polygalacturonase was properly localized in cell walls of transgenic tissue; (6) the protein was enzymically active in vitro; however, (7) accumulation of PGPA and PGSB in cell walls of transgenic tobacco did not result in pectin degradation in vivo. These results indicated that tomato polygalacturonase was properly processed and transported to the cell wall of tobacco. However, accumulation of the two polygalacturonase isozymes expressed in this heterologous host was insufficient to promote polyuronide degradation in tobacco leaf tissue.

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Section: Discussionmentioning

confidence: 99%

Analysis of tomato polygalacturonase expression in transgenic tobacco.

et al. 1990

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“…The loss of pectic substances in the middle lamellae of the cell wall is perhaps the key step in ripening process that leads to the loss of cell integrity or firmness (Solomes; Latics, 1973). The desired effect of calcium in maintaining fruit firmness may be due to the calcium binding to free carboxyl groups of polygalacturonate polymer, stabilizing and strengthening the cell wall, which in turn may strengthen the tissue thus becoming more resistant to hydrolytic enzyme activity, where calcium inhibits the polygalacturonase activity in cell walls (Buescher;Hobson, 1982). Results here regarding the role of CaCl 2 in the reduction of fruit softening are in correlation with those obtained on plums (Kirmani et al, 2013) and strawberry (Muñoz et al, 2008).…”

Section: Decay (%)mentioning

confidence: 99%

Pre-harvest application of calcium chloride and chitosan on fruit quality and storability of ‘Early Swelling’ peach during cold storage

et al. 2017

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Studies related with the storage of peach fruits have received great relevance in Egypt. In this study, the effect of pre-harvest sprays of calcium chloride and chitosan, separately and in combination, on quality attributes and storability of peach fruits stored at 0±1 °C was studied. 'Early Swelling' peach trees were sprayed twice with 1% or 2% calcium chloride. The first spraying was at pea stage, while the second one was performed at 10 days before harvesting. Chitosan sprays were performed at 0.5 or 1%, alone or in combination with 1 and 2% calcium chloride, at 10 days before harvesting. Untreated trees served as control. Fruits were harvested at maturity stage, then packaged and stored at 0±1 °C and 85-90% of relative humidity. Fruit physical and chemical properties were evaluated at 7-day intervals. Results showed that pre-harvest application with 2% CaCl 2 +1% chitosan was most effective in minimizing weight loss (%) and decay (%), as well as in maintaining maximum firmness and lengthening shelf life. Fruit color was not affected by any of the treatments, while untreated fruits and calcium chloride treatment alone, at both applied concentrations, maintained higher total soluble solids (TSS, %), total phenolic content, and lower titratable acidity percentage.Index terms: Alternative chemicals; CaCl 2 ; quality attributes. RESUMOEstudos relacionados ao armazenamento de pêssego tem sido considerado de grande relevância no Egito. Neste estudo, o efeito da pulverização pré-colheita com cloereto de calico e quitosano, isoladamente ou em conjunto, na qualidade e na capacidade de armazenamento de frutos de pessegueiro armazenados a 0±1 °C foi avaliada. Frutos da variedade 'Early Swelling' foram tratados com 1,0 ou 2,0% de cloreto de cálcio. O primeiro tratamento foi aplicado num estado precoce de formação do fruto enquanto o segundo foi aplicado 10 dias antes da colheita. Quitosano foi aplicado nas concentrações de 0,5 ou 1,0%, isoladamente ou em combinação com 1,0% ou 2,0% de cloreto de cálcio também 10 dias antes da colheita. Árvores não tratadas serviram como controle. Os frutos foram colhidos quando maduros, empacotados e mantidos a 0±1 °C e sob condições de humidade relativa de 85-90%. Propriedades físicas e químicas dos frutos foram avaliadas em intervalos de 7 dias. Os resultados mostraram que a aplicação de 2% CaCl 2 + 1% quitosano foi a mais eficaz em minimizar a perda de peso (%) e a senescência (%), bem como na manutenção da rigidez e aumento do período de vida em prateleira. A cor dos frutos não foi afectada por nenhum dos tratamentos enquanto frutos não tratados e cloreto de cálcio isoladamente, em ambas as concentrações, mantiveram um elevado teor de sólidos solúveis totais (TSS, %), elevado teor de fenóis e reduzida percentagem de acidez de titulação.Termos para indexação: Químicos alternativos; CaCl 2 ; atributos qualitativos.

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“…In tomato fruit, Ca2' regulation has been implicated in the regulation of fruit softening (7), calmodulin-mediated protein ' phosphorylation during fruit ripening (25), and in chilling injury (21,22). Here we have investigated the mechanisms and temperature dependence of ATP-dependent Ca2" transport in a tonoplast enriched membrane fraction isolated from mature-green tomato fruit.…”

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confidence: 99%