Evolution and functional divergence of MADS-box genes in Pyrus

Area of Science:

• Plant genetics
• Molecular biology
• Evolutionary biology

Background:

• MADS-box transcription factors are crucial regulators of plant growth, development, and reproduction.
• Previous characterization of MADS-box genes has been limited in closely related plant species.

Purpose of the Study:

• To identify and characterize MADS-box genes in European pear (Pyrus communis) and Chinese pear (Pyrus bretschneideri).
• To investigate the phylogenetic relationships, chromosomal distribution, and evolutionary mechanisms of MADS-box genes in these species.
• To explore the expression profiles and potential functional divergence of MADS-box genes in pear fruits.

Main Methods:

• Bioinformatic analysis to identify MADS-box genes.
• Phylogenetic analysis to cluster genes into groups and subfamilies.
• Analysis of gene duplication events (tandem, segmental, whole genome duplication).
• Gene expression profiling in pear fruits.

Main Results:

• Identified 73 MADS-box genes in P. communis and 74 in P. bretschneideri.
• Genes clustered into five main groups (Mα, Mβ, Mr, MIKC^C, MIKC*), with MIKC^C further divided into 10 subfamilies.
• Significant non-random distribution of MADS-box genes on chromosomes.
• Identified 37 orthologs and numerous paralogs, with segmental duplication and whole genome duplication being major drivers of gene family expansion.
• Expression profiles suggested functional divergence and neo- or sub-functionalization of orthologous genes.

Conclusions:

• Segmental duplication and whole genome duplication events significantly contributed to the expansion of the MADS-box gene family in pears.
• Functional divergence and neo- or sub-functionalization of orthologous MADS-box genes provide insights into species differentiation and biodiversity formation.
• This study offers a valuable reference for understanding MADS-box gene evolution in closely related plant species.