MADS-box genes are involved in floral development and evolution.

Area of Science:

• Plant molecular biology
• Evolutionary genetics
• Developmental biology

Background:

• MADS-box genes encode transcription factors crucial for eukaryotic development, particularly in plants where they regulate floral development and organ identity.
• Plant MADS-box proteins are typically of the MIKC type, characterized by M, I, K, and C domains.
• These genes control key developmental transitions, including the switch to reproductive growth and the establishment of floral meristem identity.

Purpose of the Study:

• To investigate the evolutionary history and potential novel functions of MADS-box genes across different plant lineages.
• To explore the phylogenetic relationships of MADS-box genes in ferns, gymnosperms, and angiosperms.
• To propose a new hypothesis regarding the role of MADS-box gene clades in plant sex determination.

Main Methods:

• Phylogenetic analysis of MADS-box gene sequences from ferns, gymnosperms, and higher eudicots.
• Identification and characterization of MADS-box gene orthologs in various plant groups.
• Comparative genomics to infer evolutionary origins and relationships.

Main Results:

• Ferns possess MIKC-type MADS-box genes, but they are not orthologous to those in gymnosperms or angiosperms.
• Orthologs of floral homeotic B- and C-function genes were identified in gymnosperms, suggesting ancient origins (300-400 million years ago).
• A novel gene clade, Bsister, was discovered in both gymnosperms and angiosperms, related to the B-genes.

Conclusions:

• The evolution of MADS-box genes involved diversification and duplication events predating angiosperms.
• The Bsister clade represents a significant evolutionary innovation within MADS-box genes.
• A novel hypothesis suggests that B and Bsister genes may play roles in male and female reproductive organ determination, respectively.