Spatial and Temporal Content Levels of Anthocyanin and the Expression Characters of Some Related Genes in Betula pendula

In this study, 3-year-old clones of Purple Betula platyphylla were used as the test materials, of which the anthocyanin and chlorophyll contents in the top, middle and bottom leaves from 1 branch and the leaves of different development stages were measured. In addition, the spatial and temporal expression levels on the BpCHS and BpDFR family genes were measured by qRT-PCR. The results showed that the differences in the anthocyanin and chlorophyll content among the top, middle and bottom leaves from the same branch were significant, while the anthocyanin of the 2 different development stages was also significant. The first and second leaves nearest to the bud were dark purple or violet from May to August in B. pendula, while the anthocyanin content in the top leaves was higher than those of the middle and bottom leaves in all of the development stages. The trends of anthocyanin and chlorophyll contents in the top, middle and lower leaves showed opposite trends, and the linear regression analysis showed that the 2 types of pigment content had an extremely significant linear negative correlation. The spatial and temporal expression characters of 3 BpCHS genes and 4 BpDFR genes showed that when the leaves were dark purple or violet, the expression levels of BpCHS2 and BpCHS3 were the highest. When the leaf color became obvious in the top, middle and bottom, 4 BpDFR genes performed in an up-regulated or down-regulated manner. Accordingly, it was certain that the leaf color of the B. pendula was related to BpCHS2, BpCHS3 and BpDFR.