ABA influences color initiation timing in P. avium L. fruits by sequentially modulating the transcript levels of ABA and anthocyanin-related genes

In sweet cherry, as in most non-climacteric species, abscisic acid (ABA) plays a major role in the control of fruit ripening and color development. Although the ABA treatment of sweet cherry fruits has been reported to upregulate anthocyanin pathway-related genes or ABA pathway-related genes, the temporality of molecular and physiological events occurring during color development and the ABA control of these events during the color initiation are lacking in this species. In this work, we analyzed variations in the Index of Absorbance Difference (IAD), a maturity index, and total anthocyanins along with changes in transcript abundance of ABA and anthocyanin pathway-related genes, from light green to red fruit stages. PavNCED1 and ABA signaling pathway-related genes upregulated when fruits transitioned from light green to pink stage, whereas anthocyanin pathway-related transcripts increased from pink to the red stage, together with increases in the anthocyanin content and IAD, suggesting sequentiality in molecular and physiological events during color development. Additionally, ABA applied at color initiation in planta advanced IAD, increased anthocyanin content, and yielded darker fruits at harvest. These changes were accompanied by changes in the transcript accumulation of ABA and anthocyanin pathway-related genes. This in planta treatment of sweet cherry fruits with ABA confirms that ABA is a central player in the control of color initiation in sweet cherries, associated with the transcript accumulation of genes involved in ABA homeostasis and signaling, which is followed by the up-regulation of anthocyanin pathway-related genes and color development.

Automated summary

This study found that in sweet cherry fruits, ABA-related genes and anthocyanin pathway-related genes are upregulated during the transition from light green to pink stage, while the abundance of anthocyanin pathway-related transcripts increases from pink to red stage, indicating a sequential relationship between molecular and physiological events during color development. Additionally, ABA treatment at color initiation in planta results in advanced fruit maturity, increased anthocyanin content, and darker fruits at harvest, accompanied by changes in the transcript accumulation of ABA and anthocyanin pathway-related genes. This confirms ABA's central role in controlling color initiation in sweet cherries, with ABA homeostasis and signaling genes being up-regulated followed by anthocyanin pathway-related genes during color development.