Papaya pulp gelling: is it premature ripening or problems of water accumulation in the apoplast?

Abstract

-Gelled aspect in papaya fruit is typically confused with premature ripening. This research reports the characterization of this physiological disorder in the pulp of papaya fruit by measuring electrolyte leakage, Pi content, lipid peroxidation, pulp firmness, mineral contents (Ca, Mg and K -in pulp and seed tissues), and histological analysis of pulp tissue. The results showed that the gelled aspect of the papaya fruit pulp is not associated with tissue premature ripening. Data indicate a reduction of the vacuole water intake as the principal cause of the loss of cellular turgor; while the waterlogged aspect of the tissue may be due to water accumulation in the apoplast. Index terms: ultrastructural alterations, cell turgor, fruit quality, physiological disturbances, biochemical alterations. GELEIFICAÇÃO DA POLPA DE MAMÃO: AMADURECIMENTO PREMATURO OU PROBLEMAS NO ACÚMULO DE ÁGUA NO APOPLASTO?RESUMO -O aspecto geleificado da polpa de mamão é constantemente confundido com amadurecimento prematuro. Este trabalho caracterizou esse distúrbio fisiológico na polpa de frutos de mamão através de medidas de liberação de eletrólitos, conteúdo de Pi, peroxidação lipídica, firmeza da polpa, condudo mineral (Ca, Mg e K -na polpa e semente) e análises histológicas da polpa. Os resultados mostram que o aspecto geleificado da polpa de mamão não está associado com o amadurecimento prematuro. Os resultados indicam uma redução da entrada de água no vacúolo como a principal causa da perda de turgor celular, enquanto o aspecto encharcado da polpa pode ser devido ao acúmulo de água no apoplasto. Termos para indexação: alterações ultra estruturas, turgor celular, qualidade de frutos, distúrbios fisioló-gicos, alteraçõs bioquímicas.Rev. Bras. Frutic., Jaboticabal -SP, v. 32, n. 4, p. 961-969, Dezembro 2010 962

Papaya: Nutritional and pharmacological characterization, and quality loss due to physiological disorders. An overview

“…However, fruits with flesh translucency could have multiple causes that lead to same symptoms. Oliveira et al (2010) showed that Ca ++ levels were neither different (Pb 0.05) in seeds nor the pulp of the flesh translucency of the papaya when compared with healthy fruit. Similarly, pulp firmness was also not found to differ from that of healthy material (Oliveira et al, 2010) implying that papaya pulp flesh translucency is unrelated to the Ca ++ deficiency, but more specifically to the proton pumps (Azevedo et al, 2007).…”

“…Physiological disorders of the most varied causes are common in many fruit species (Chatenet et al, 2000;Paull & Reyes, 1996;Roper, 1999), and the papaya is not an exception (Kaiser, Allan, White, & Dehrmann, 1996;Oliveira et al, 2010;Reyes, Eloisa, & Paull, 1994;Schripsema, Vianna, Rodrigues, Oliveira, & Franco, 2010). These disturbances are almost always related to environmental factors Oliveira, Pereira, Martelleto, & Ide, 2005;Oliveira et al, 2004;Oliveira et al, 2002) which, in certain cases, are difficult for growers to prevent.…”

“…6E). Oliveira et al (2010) reported that 'Golden' papaya pulp flesh translucency is not related to premature ripening of tissue, and not directly related to a Ca ++ deficiency in the fruit. Data suggest, rather, that this physiological disorder is caused by a reduction in water entering the vacuole and consequently a loss of cellular turgescence.…”

“…In preliminary analyses, the functions of the pumps present in the plasmatic membrane of the papaya pulp flesh translucency tissues showed a reduction in the supply of energy made available for the transport of ions and other solutions such as sucrose into the cytoplasm (Azevedo et al, 2007), partially explaining the lower concentration of K + and total soluble solids reported by Oliveira et al (2010) in the pulp tissue of fruits with flesh translucency. According to Azevedo et al (2007), tissue with pulp flesh translucency presented an increase in the permeability of the tonoplast.…”

Functional uncoupling of the tonoplast proton pump and its effect on the flesh gelling physiological disorder in papaya fruit

“…Transmission electron microscopy analysis previously performed by Campos et al (2004) and Oliveira et al (2010) revealed that the pulp tissues in gelled papayas exhibited cells with intense plasmolysis and unbroken cell walls. The irregular contours of gelled tissue cells may be the result of excessive water loss from these cells to the apoplastic environment, which could account for the soaked appearance of the gelled mesocarp as suggested by Oliveira et al (2010).…”