The haplotype-resolved T2T genome for Bauhinia × blakeana sheds light on the genetic basis of flower heterosis.
Gigascience, 2025/1/06;14
Mu W[1, 2], Darian JC[3], Sung WK[4, 5, 6], Guo X[7], Yang T[8], Tang MWM[1], Chen Z[9], Tong SKH[10, 11], Chik IWS[10], Davidson RL[12], Edmunds SC[13], Wei T[7], Tsui SK[1, 2]
Affiliations
PMID: 40276955DOI: 10.1093/gigascience/giaf044
Impact factor: 7.658
Abstract
background: The Hong Kong orchid tree Bauhinia × blakeana Dunn has long been proposed to be a sterile interspecific hybrid exhibiting flower heterosis when compared to its likely parental species, Bauhinia purpurea L. and Bauhinia variegata L. Here, we report comparative genomic and transcriptomic analyses of the 3 Bauhinia species.
findings: We generated chromosome-level assemblies for the parental species and applied a trio-binning approach to construct a haplotype-resolved telomere-to-telomere (T2T) genome for B. blakeana. Comparative chloroplast genome analysis confirmed B. purpurea as the maternal parent. Transcriptome profiling of flower tissues highlighted a closer resemblance of B. blakeana to its maternal parent. Differential gene expression analyses revealed distinct expression patterns among the 3 species, particularly in biosynthetic and metabolic processes. To investigate the genetic basis of flower heterosis observed in B. blakeana, we focused on gene expression patterns within pigment biosynthesis-related pathways. High-parent dominance and overdominance expression patterns were observed, particularly in genes associated with carotenoid biosynthesis. Additionally, allele-specific expression analysis revealed a balanced contribution of maternal and paternal alleles in shaping the gene expression patterns in B. blakeana.
conclusions: Our study offers valuable insights into the genome architecture of hybrid B. blakeana, establishing a comprehensive genomic and transcriptomic resource for future functional genetics research within the Bauhinia genus. It also serves as a model for exploring the characteristics of hybrid species using T2T haplotype-resolved genomes, providing a novel approach to understanding genetic interactions and evolutionary mechanisms in complex genomes with high heterozygosity.
Keywords: Bauhinia × blakeana ; flower heterosis; genome evolution; transcriptome profiling; trio-binning
MeSH terms
Hybrid Vigor; Flowers; Haplotypes; Bauhinia; Gene Expression Regulation, Plant; Genome, Plant; Gene Expression Profiling; Transcriptome
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