Biochemical differences in the skin of two blueberries (Vaccinium corymbosum) varieties with contrasting firmness: Implication of ions, metabolites and cell wall related proteins in two developmental stages

• Published in: Plant physiology and biochemistry 2021-05, Vol.162, p.483-495
• Main Authors: Montecchiarini, M.L., Silva-Sanzana, C., Valderramo, L., Alemano, S., Gollán, A., Rivadeneira, M.F., Bello, F., Vázquez, D., Blanco-Herrera, F., Podestá, F.E., Tripodi, K.E.J.
• Format: Article
• Language: English
• Subjects: Abscisic acid; Aquaporin; Blueberry Plants; Boron; Catechin; Cell Wall; Fruit; Ions; Pectin methyl esterase; Pectins
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2021.03.016

The pursuit of firmer and better-quality blueberries is a continuous task that aims at a more profitable production. To this end it is essential to understand the biological processes linked to fruit firmness, which may diverge among tissues. By contrasting varieties with opposing firmness, we were able to elucidate events that, taking place at immature stage, lay the foundation to produce a firmer ripe fruit. A deep analysis of blueberry skin was carried out, involving diverse comparative approaches including proteomics and metabolomics coupled to immunolocalization assays. In‘O'Neal’ (low firmness) enhanced levels of aquaporins, expansins and pectin esterases at the green stage were found to be critical in distinguishing it from ‘Emerald’ (high firmness). The latter featured higher levels of ABA, low methyl esterified pectins in tricellular junctions and high levels of catechin at this stage. Meanwhile, in ‘Emerald’ ‘s ripe fruit epicarp, several mechanisms of cell wall reinforcement such as calcium and probably boron bridges, appear to be more prominent than in ‘O'Neal’. This study highlights the importance of cell wall reorganization and structure, abundance of specific metabolites, water status, and hormonal signalling in connection to fruit firmness. These findings result particularly valuable in order to improve the fertilization procedures or in the search of molecular markers related with firmness. [Display omitted] •High levels of aquaporins, expansins and pectin esterases are involved in early cell wall modifications.•Abundant wall lytic enzymes and less calcium bridges at ripe stage features the less firm variety.•Catechin, malic acid, boron and ABA, might be engaged in mechanical cell wall reinforcement.