Proteomics Of The Ripening Of Blackberry Fruits (Rubus Sp.) Grown In Mexico, A First Approach

Blackberry production in Mexico has increased 200 % in the last decade. The main varieties used have been introduced from other countries, and its establishment under the climatic conditions of Mexico has required considerable adaptations to the agronomic management observed in the regions of origin thereof. The essential challenge of managing this product is based on the intrinsic characteristics of its soft fruit and its short shelf life, so that knowledge of their maturation process under their growing conditions in Mexico is imperative to achieve and improve handling productivity and fruit quality unto its final destination. The aim of this work was to first address this problem by establishing the conditions of protocols for the analysis of proteins in blackberry fruits during different ripening stages. To accomplish this goal, six stages of fruit ripening were identified for the commercial variety 'Brazos'(considering a range of development from green, small fruits to fruits fully developed and in harvest maturity), a protein extraction was selected and a protein profile was performed by electrophoresis under denaturing conditions. In addition, requirements were established for two-dimensional electrophoresis (2-DE) of the extracts obtained by evaluating the conditions of isoelectric focusing and staining methods. According to the results obtained, it was determined to use 400 ae g of total protein in IPG strips of 7 cm with a pH range of 3 to 10, using a maximum voltage of 50 000 V, and Coomassie blue staining. A preliminary analysis of the distribution and abundance of the peptides expressed in the six stages of maturation was performed using the KODAK MI software version 4.5, and the results showed that the stage 2 presented the highest number of peptide spots (158), the highest percentage of spots at all stages were observed in a pH range of 5.0 to 6.9 and molecular weight of 30 to 50 kDa. We identified four spots of similar intensity, suggesting its constitutive expression, three of decreasing expression; that could be involved in the initial processes of fruit growth, four spots of induced expression, and six of oscillating degrees of expression during ripening.