Isolation and gene expression analysis of postharvest senescence marker in baby spinach leaves

Spinach leafy vegetables undergo several mechanical processes during the postharvest stage that may induce tissue damage and quality losses. The membrane degradation may activate several postharvest problems with involvement of ascorbic acid degradation. Ascorbic acid is highly perishable and can be an indicator of freshness or leaf senescence. However, through bioinformatic investigations putative senescence postharvest markers were identified. These genes were isolated using degenerate primers and cloned. Spinach leaves were harvested at commercial stage, cut in six pieces and stored at 20°C. The control was represented by intact leaves stored at the same conditions of treatment. The ascorbic acid was measured in spinach leaves until 3 days of storage. Gene expression analyses of a putative cysteine protease (SoSAG12) were determined at different sampling points. Results observed showed a decrease of ascorbic acid immediately after wounding and during storage. The expression of SoSAG12 was enhanced in wounded tissues as soon as after 6h.