Expression of BoNOL and BoHCAR genes during postharvest senescence of broccoli heads.

Abstract

Chlorophyll is the most abundant pigment on Earth, essential for the capture of light energy during photosynthesis. During senescence, chlorophyll degradation is highly regulated in order to diminish toxicity of the free chlorophyll molecule due to its photoactivity. The first step in the chlorophyll degradation pathway is the conversion of chlorophyll b to chlorophyll a by means of two consecutive reactions catalyzed by enzymes coded by NYC1 (NON-YELLOW COLORING 1), NOL (NYC1-LIKE) and HCAR. In this work, we studied the expression of NOL and HCAR genes during postharvest senescence of broccoli. We found that the expression of BoNOL increase during the first days of storage and then decrease. In the case of BoHCAR, its expression is maintained during the first days and then it also diminishes. Additionally, the effect of different postharvest treatments on the expression of these genes was also analyzed. It was observed that the expression of BoNOL is lower in the treatments performed with 1-methylcyclopropene (1-MCP), 6-benzylaminopurine (6-BAP) and modified atmospheres, while BoHCAR expression showed an increase in these same treatments, and a decrease in the treatment with ethylene. There were no variations in the expression of both genes in heat treatment, UV-C treatment and visible light treatment. These results suggest that both BoHCAR and BoNOL show a lower regulation of their expression than other genes involved in chlorophyll degradation during senescence. © 2020 Society of Chemical Industry.