Background
The red-leaved poplar cultivars ‘Quanhong’ and ‘Xuanhong’ are bud mutations of Populus deltoides cv. ‘Zhonglin 2025’. These cultivars are valued for their beautiful shape, lack of flying catkins, and ornamental leaf colors. The molecular mechanism that leads to different leaf colors between these red-leaved poplars and ‘Zhonglin 2025’ remains unclear.
Results
In this study, we analyzed growth and physiological indicators in the ‘Quanhong’, ‘Xuanhong’, and ‘Zhonglin 2025’ poplar cultivars, and performed transcriptome and proteome analysis of their leaves. The results showed that plant height and ground diameter were significantly lower in both red-leaved poplars than in ‘Zhonglin 2025’, indicating that their growth and development were markedly inhibited. The ratio of anthocyanin to total chlorophyll and photosynthetic capacity of the leaves were higher and lower, respectively, in the red-leaved cultivars than in ‘Zhonglin 2025’. At the transcript and protein levels, 6,792 differentially expressed genes (DEGs) and 2,786 differentially expressed proteins (DEPs) were screened in the ‘Quanhong’ cultivar, respectively, and 4,398 DEGs and 2,333 DEPs were screened in the ‘Xuanhong’ cultivar, respectively. We screened 769 DEGs/DEPs in ‘Quanhong’ and 399 DEGs/DEPs in ‘Xuanhong’ in an integrated transcriptomics/proteomics analysis. Based on the results of this integrated analysis, 15 and 11 genes/proteins involved in anthocyanin synthesis were further identified in ‘Quanhong’ and ‘Xuanhong’, respectively, including the CHS , F3H , and DFR genes. Among the 120 transcription factors, 3 (HY5, HYH, and TTG2), may be directly involved in the regulation of anthocyanin synthesis in both red-leaved poplars.
Conclusions
By comparing the proteomes and transcriptomes of red-leaved poplar cultivars and ‘Zhonglin 2025’, we identified the key genes and proteins related to red leaf coloration. The findings of this study provided insights that may aid further studies of the molecular mechanism of leaf red coloration in red-leaved poplars.
