Elevated CO₂ delayed the chlorophyll degradation and anthocyanin accumulation in postharvest strawberry fruit

Colour is an important quality attribute for the consumer's acceptability of fruit. Elevated CO₂ was applied to strawberry fruit to explore its influence on chlorophyll catabolism and anthocyanin synthesis. The results showed that 20% CO₂ delayed the changes of a^* and b^* values in strawberry fruit. The degradation of chlorophyll was delayed in CO₂ treated fruit by inhibiting the activities of chlorophyllase and down-regulating the expression of FaChl b reductase, FaPAO and FaRCCR. In addition, lower concentration of anthocyanins and lower activity of PAL, C4H, 4CL and CHS were recorded under the effect of 20% CO₂. Meanwhile, qRT-PCR analysis showed that 13 genes involved in the phenylpropanoid pathway and the flavonoid biosynthesis pathway were also down-regulated under CO₂ stress. However, no residual effect on pigment metabolism was observed when elevated CO₂ was removed. Our study provided new insights into the regulation of elevated CO₂ in the role of pigment metabolism in postharvest.