Physiological and Genomic Analysis Reveals Candidate Genes Involved in Anthocyanin Biosynthesis in Colored-leaf Poplar ‘Caihong’ (Populus deltoides)

Leaf color is an important agronomic trait that contributes to the ornamental value of plants. However, the molecular mechanism of leaf coloration is still unclear. In our study, a colored-leaf poplar ‘Caihong’ (CHP, bright red leaves) and wild-type L2025 (green leaves) were used to explore the mechanism of leaf coloration by physiological and genomic analysis. Compared with leaves of L2025, leaves of CHP had a higher content of anthocyanins and a lower content of total Chl and carotenoids, and the ratio of anthocyanins to total Chl in CHP was more than 10 times of those in L2025, which may be the physiological reason why they show red leaf color. Based on the whole genome resequencing and bioinformatics analysis, eight structural genes and 20 regulatory genes associated with anthocyanin biosynthesis carrying more than five non-synonymous SNPs in coding regions were screened. These candidate genes were also identified according to the qRT-PCR analysis, and eight structural genes and three MYB family genes might play important roles in the leaf coloration of CHP. The above results could provide reference to explore the molecular regulation mechanism of leaf coloration in <i>Populus deltoids</i>, and also provided insight into coloration of other woody plants.