A research team led by Professor Sun Lidan from Beijing Forestry University's College of Landscape Architecture has unveiled the genomic origins of purple pigmentation in Prunus mume 'Meiren', with findings published in Plant Biotechnology Journal online. This breakthrough provides crucial insights for precision breeding of ornamental woody plants.

The genome assembly and haplotype-chromosome construction of P. mume ‘Meiren’.

Prunus mume, an important ornamental woody plant in the Rosaceae family, contains many interspecific hybridizations. Purple colour is a breeding trait of aesthetic value for P. mume, but little is known about the origin and genetic architecture of this trait. Here the research addresses these issues by producing a haplotype-resolved genome from an interspecific hybrid cultivar of P. mume (M) and P. cerasifera 'Pissardii' (C), named P. mume 'Meiren', followed by a detailed molecular characterization. The final length of the diploid genome is 499.47 Mb, with 250.66 Mb of haplotype M (HM) and 248.79 Mb of haplotype C (HC). Approximately 95.42% (476.61 Mb) of the phased assembly is further anchored to 16 homologous chromosomes. Based on the genomic variation, the researchers identify a 1.8 Mb large-fragmented inversion (INV) on chromosome 1b of HC, which co-segregates with purple colour traits of 'Meiren' inherited from its purple C parent 'Pissardii'. The team finds that a MYB transcription factor, PmmMYB10.5b, resides at the distal breakpoint of the INV, which displays consistent allele-specific expression (ASE). By directly binding to the promoter of anthocyanin synthetic alleles, PmmMYB10.5b serves as a co-activator to promote anthocyanin accumulation in 'Meiren' organs. Notably, the INV identified in 'Meiren' is generated from 'Pissardii' rather than P. cerasifera , which alters the promoter sequence of PPmmMYB10.5b, activates its expression and results in the purple colour trait. Results from this study shed light on the evolutionary origin of purple colour in 'Meiren' and could potentially provide guidance on the genetic improvement of colour traits in ornamental woody plants.

Model depicting the genetic evolution of purple colour and PmmMYB10.5b initial regulatory pattern of anthocyanin biosynthesis.

Meng Juan and Li Liwei, PhD candidates at the School of Landscape Architecture, are the co-first authors of the paper, with Professor Sun Lidan serving as the corresponding author. Beiing Forestry University is the signatue unit of the first author.

This research was supported by the Fundamental Research Funds for Central Universities (Grant No. QNTD202306), the Forestry and Grassland Science and Technology Innovation Youth Top Talent Project of China (Grant No. 2020132608), and the Beijing High-Precision Discipline Project in the field of Ecological Environment of Urban and Rural Human Settlements.

Paper link: http://doi.org/10.1111/pbi.14595

Written by Sun Lidan, Meng Juan
Translated and edited by Song He
Reviewed by Yu Yangyang