Evolutionary Dynamics of the Tubulin Gene Family Across Plants and Identification of PaTUA1 as a Candidate Gene Associated with Apricot Kernel Development

Tubulins are essential cytoskeletal components involved in plant cell division and expansion, yet their evolutionary dynamics across plant lineages and potential roles in horticultural seed/kernel development remain insufficiently understood. Here, we identified 2535 tubulin-related genes from 97 plant genomes and performed an integrated phylogenomic analysis. Phylogenetic and synteny network analyses resolved four ancient clades, including α-, β-,γ-tubulin and FtsZ, all of which were predominantly subjected to purifying selection. The α- and β-tubulin subfamilies exhibited lineage-specific expansion in angiosperms, particularly in eudicots, and these expansions were associated with ancient WGD and WGT events while retaining relatively conserved chromosomal contexts. By employing a pyramid-structured microsynteny framework across 12 Rosaceae genomes, we further traced the orthologous conservation and lineage-specific rearrangements of tubulin loci, with Prunus armeniaca as a reference. Spatiotemporal transcriptome profiling of Siberian apricot and kernel apricot revealed a group of tubulin genes highly expressed during key stages of kernel development, highlighting PaTUA1 as a priority candidate gene. Transient overexpression of PaTUA1 in wounded developing apricot kernels was associated with short-term increases in average phytohormone concentrations, including IAA, GA3, BR, and cytokinins. Together, these results suggest that PaTUA1 represents a promising candidate gene associated with hormone-related responses during apricot kernel development, providing a basis for future functional validation rather than direct evidence of kernel-size determination.