Carbon metabolism of peach fruit after harvest: changes in enzymes involved in organic acid and sugar level modifications

Abstract

Peach (Prunus persica L. Batsch) is a climacteric fruit that ripens after harvest, prior to human consumption. Organic acids and soluble sugars contribute to the overall organoleptic quality of fresh peach; thus, the integrated study of the metabolic pathways controlling the levels of these compounds is of great relevance. Therefore, in this work, several metabolites and enzymes involved in carbon metabolism were analysed during the post-harvest ripening of peach fruit cv 'Dixiland'. Depending on the enzyme studied, activity, protein level by western blot, or transcript level by quantitative real time-PCR were analysed. Even though sorbitol did not accumulate at a high level in relation to sucrose at harvest, it was rapidly consumed once the fruit was separated from the tree. During the ripening process, sucrose degradation was accompanied by an increase of glucose and fructose. Specific transcripts encoding neutral invertases (NIs) were up-regulated or down-regulated, indicating differential functions for each putative NI isoform. Phosphoenolpyruvate carboxylase was markedly induced, and may participate as a glycolytic shunt, since the malate level did not increase during post-harvest ripening. The fermentative pathway was highly induced, with increases in both the acetaldehyde level and the enzymes involved in this process. In addition, proteins differentially expressed during the post-harvest ripening process were also analysed. Overall, the present study identified enzymes and pathways operating during the post-harvest ripening of peach fruit, which may contribute to further identification of varieties with altered levels of enzymes/metabolites or in the evaluation of post-harvest treatments to produce fruit of better organoleptic attributes.

Metabolic Profiling during Peach Fruit Development and Ripening Reveals the Metabolic Networks That Underpin Each Developmental Stage

“…In higher plants, the final step of ethylene synthesis is catalyzed by the enzyme 1-aminocyclopropane-1-carboxylic acid oxidase (ACO). Previous work demonstrated that an accumulation of mRNA encoding peach ACO1 (PpACO1) correlates with the actual ethylene production by peach fruit (Tonutti et al, 1997;Ruperti et al, 2001;Borsani et al, 2009). Thus, in order to determine the onset and further progress of the ripening syndrome in Dixiland peach fruit, the PpACO1 level was determined by quantitative real-time reverse transcription (qRT)-PCR during peach fruit development and ripening.…”

Tratamentos hidrotérmico e com radiação UV-C no controle pós-colheita da podridão olho-de-boi em uma linha comercial de seleção de maçãs

“…Porém, avaliou-se apenas a infecção natural de C. perennans, que corresponde ao patógeno presente no fruto antes da colheita, mas que, devido aos mecanismos de defesa do vegetal, não há manifestação de sintomas da doença (VALDEBENITO-SANHUEZA, 2002). Assim, em pós-colheita, quando diminuem os mecanismos de defesa dos frutos, associados às temperaturas próximas de 20ºC, o patógeno desenvolve a podridão (BORSANI et al, 2009).…”

“…Os frutos imaturos apresentam maior resistên-cia a patógenos, sendo que as mudanças fisiológicas verificadas na pós-colheita aumentam a suscetibilidade da parede celular às enzimas pectinolíticas produzidas pelos patógenos, favorecendo a infecção (BORSANI et al, 2009). A incidência da infecção ocasionada por C. perennans em maçãs é maior quando o fruto está próximo do ponto de colheita, mas as maiores perdas ocorrem durante e após o armazenamento refrigerado (VALDEBENITO-SANHUEZA, 2002).…”

Suppression of glutamate synthase genes significantly affects carbon and nitrogen metabolism in rice (Oryza sativa L.)

“…We used the method of Scheible et al [26] to assay nitrite reductase (NiR) and that of Turano et al [27] to assay glutamate dehydrogenase (GDH). Malate dehydrogenase (NADP-MDH) was assayed as described by Jenner et al [28] and pyruvate kinase (PK) as described by Borsani et al [29].…”