The citrus fruit proteome: insights into citrus fruit metabolism

Abstract

Fruit development and ripening are key processes in the production of the phytonutrients that are essential for a balanced diet and for disease prevention. The pathways involved in these processes are unique to plants and vary between species. Climacteric fruit ripening, especially in tomato, has been extensively studied; yet, ripening of non-climacteric fruit is poorly understood. Although the different species share common pathways; developmental programs, physiological, anatomical, biochemical composition and structural differences must contribute to the operation of unique pathways, genes and proteins. Citrus has a non-climacteric fruit ripening behavior and has a unique anatomical fruit structure. For the last few years a citrus genome-wide ESTs project has been initiated and consists of 222,911 clones corresponding to 19,854 contigs and 37,138 singletons. Taking advantage of the citrus database we analyzed the citrus proteome. Using LC-MS/MS we analyzed soluble and enriched membrane fractions of mature citrus fruit to identify the proteome of fruit juice cells. We have identified ca. 1,400 proteins from these fractions by searching NCBI-nr (green plants) and citrus ESTs databases, classified these proteins according to their putative function and assigned function according to known biosynthetic pathways.

Physiology of citrus fruiting

“…The suggestion also provides a convincing explanation for the strong reduction of both citrate and cytoplasmatic acidity that takes place in citrus fruit flesh during development and ripening. In a study work Katz et al (2007) analyzed soluble and enriched membrane fractions of mature citrus fruit and identified ca 1,400 proteins of fruit juice cells including proteins involved in sugar metabolism, citrate cycle, signalling, transport, and processing. This effort may open new insights to the regulation of internal ripening in citrus.…”

Comparative proteomic analysis between early developmental stages of the Coffea arabica fruits

“…The enzymes fructose bisphosphate aldolase and glyceraldehyde-3-phosphate dehydrogenase have also been identified in proteomic studies of apple, strawberry (Zheng et al, 2007), and tomato (Faurobert et al, 2007). Malate dehydrogenase has been identified in citrus studies (Katz et al, 2007). Despite the fact that both enzymes are involved in carbohydrate anabolism and catabolism, their higher expression in stage 2 suggests activation of the glycolytic pathway.…”

“…Although different species share common pathways and developmental programs, the physiological, anatomical, and biochemical compositions and structural differences must contribute to the operation of unique pathways, genes, and proteins (Katz et al, 2007). The elucidation of the molecular basis of such early and common events represents an active frontier in fruit ripening research (Giovannoni, 2004).…”

Biosíntesis de Carotenoides durante la Conservación Postcosecha de Frutos Citricos

“…Los estudios sobre el perfil proteómico en frutos cítricos son escasos, limitándose al análisis del metabolismo general, durante la maduración o a la caracterización del fenotipo de mutantes (Katz et al, 2007;Alós et al, 2008;Muccilli et al, 2009). En lo referente a postcosecha, los trabajos se han centrado en el estudio de los cambios protéicos producidos en el albedo durante la conservación refrigerada (Lliso et al, 2007).…”

“…Dado el carácter no climatérico de los frutos cítricos, se ha sugerido que el papel de la hormona durante la maduración podría ejercerse mediante cambios en la sensibilidad a la misma (Alonso et al, 1995). Sin embargo, no se han obtenido hasta la fecha evidencias claras de cambios en los niveles de los receptores del etileno que puedan justificar dichas alteraciones en la sensibilidad a la hormona (Katz et al, 2007;Rosales et al, 2009). …”