Comparative transcriptome analysis provides insights into the dwarfing mechanism of pear trees
摘要
Dwarfism is crucial for intensive cultivation and labor-saving management in modern orchards. However, the molecular mechanisms underlying pear tree dwarfing remain largely unclear. Here, we performed comparative transcriptome analysis between dwarf pear germplasm and pear cultivar ‘Cuiguan’.
ResultsThe dwarf pear germplasm exhibited significantly shorter internode and branch length compared to ‘Cuiguan’. Histological analysis revealed that cortical cells in the dwarf pear germplasm were disordered and irregular, and longer than those of ‘Cuiguan’. Comparative transcriptome analysis of shoot apex from young shoots of the dwarf germplasm and ‘Cuiguan’ was conducted and a total of 13,169 differentially expressed genes (DEGs) were identified. Functional enrichment analysis revealed that functional terms related to plant hormone biosynthesis and signal transduction were overrepresented in DEGs. Genes involved in brassinosteroid (BR) and gibberellin (GA) biosynthesis were downregulated in the dwarf germplasm. DEGs involved in transcription regulation and cell wall formation were also identified, which play potential roles in tree dwarfing. In addition, expression level of genes within the chromosomal region containing PcDw locus, which has been reported as the dominant gene controlling dwarf trait, was investigated in both the dwarf pear germplasm and ‘Cuiguan’. Based on comparative analysis, nine genes in this region are considered to be closely associated with dwarf traits.
ConclusionsThe dwarf germplasm and ‘Cuiguan’ showed distinct tissue structure, with dwarfism mainly associated with defects in cell division and elongation. Comparative transcriptome analysis identified a set of DEGs involved in plant hormones biosynthesis, signaling and transport, as well as cell wall biosynthesis, modification and degradation. By integrating transcriptome data with information related to the PcDW locus, nine genes were identified as key candidates. Overall, the results of this study provide insights for understanding the mechanisms underlying pear dwarfism.