Regulatory mechanisms of leaf color change in Acer pictum subsp. mono

Acer pictum subsp. mono is a colored leaf tree with vital ornamental and economic value. However, insufficient color change and early leaf fall in cities restrict its ornamental value. In this research, green and red leaves from wild A. p. subsp. mono were collected to study the regulatory mechanisms of leaf color change. Through the determination of plant physiological indexes, we found that the photosynthetic pigment content in red leaves decreased significantly compared with green leaves, while the anthocyanin content and antioxidant activity increased significantly compared with green leaves during the leaf color change process. Using transcriptome sequencing, we found more than 5500 differentially expressed genes, most of which were up-regulated. Many of the differentially expressed genes are involved in the anthocyanin metabolic pathway. The expression patterns of 15 key genes were investigated by quantitative real-time polymerase chain reaction. Among these genes, AmDFR and PAL1 are significant genes involved in the anthocyanin metabolic pathway, and CIPKs2, CIPKs6, CMLs1, CMLs38, AmGST1, AmGST2, GPX3, CBF, AmAPX, AmSOD, POD5, AmGR, and PSBY might be stress response genes that indirectly regulated the anthocyanin accumulation. The results showed that these genes play vital roles in the leaf color change of A. p. subsp. mono. This research will be helpful in further study of the molecular regulatory mechanisms of leaf color change and for the improvement of colored leaf plants.