Elevated CO 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 CO was applied to strawberry fruit to explore its influence on chlorophyll catabolism and anthocyanin synthesis. The results showed that 20% CO delayed the changes of a and b values in strawberry fruit. The degradation of chlorophyll was delayed in CO 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% CO. Meanwhile, qRT-PCR analysis showed that 13 genes involved in the phenylpropanoid pathway and the flavonoid biosynthesis pathway were also down-regulated under CO stress. However, no residual effect on pigment metabolism was observed when elevated CO was removed. Our study provided new insights into the regulation of elevated CO in the role of pigment metabolism in postharvest.