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Proteomic analysis of “Moncada” mandarin leaves with contrasting fruit load

Muñoz-Fambuena, Natalia, Mesejo, Carlos, Agustí, Manuel, Tárraga, Susana, Iglesias, Domingo J., Primo-Millo, Eduardo, González-Mas, M. Carmen
Plant physiology and biochemistry 2013 v.62 pp. 95-106
Citrus clementina, Citrus nobilis, Citrus unshiu, alternate bearing, catalase, clementines, flowering, leaves, mandarins, pentose phosphate cycle, protein synthesis, proteins, proteomics, trees
A proteomic approach was used to know more about the molecular mechanism related to Citrus alternate bearing. To this end, we researched protein expression differences between on-crop and off-crop “Moncada” [Clementine ‘Oroval’ (Citrus clementina Hort ex Tanaka) x ‘Kara’ mandarin (Citrus unshiu Marc. x Citrus nobilis Lou.)] mandarin leaves. This variety usually shows a remarkable behaviour in alternate production. Samples were collected in the period during which the fruit affect flowering induction. From 2D DIGE gel, 110 spots were isolated: 43 showed increased expression in the off-crop samples compared to on-crop samples, while 67 showed increased expression in the on-crop samples against off-crop samples. These spots were identified by MALDI-MS or LC-MS–MS. According to the up-expressed proteins in off-crop leaves such as proteins related to nutrient reservoir activity or to the pentose phosphate pathway, the primary metabolism was more active in off-crop trees than in on-crop trees. In contrast, the proteins up-expressed in on-crop samples such as catalase were related to the oxidoreductase activity and, therefore, the redox state seemed different for off-crop and for on-crop leaves. Other proteins with unknown functions were isolated, which could be also related to the alternate bearing and to the flowering induction.