Evolution, diversification, and expression of KNOX proteins in plants

Area of Science:

• Plant Biology
• Molecular Biology
• Genomics

Background:

• KNOX (KNOTTED1-like homeobox) transcription factors are essential regulators of plant development, particularly in leaf and meristem formation.
• KNOX proteins possess conserved domains (KNOX1, KNOX2, ELK, homeobox), with the KNATM family uniquely containing only KNOX domains.

Purpose of the Study:

• To conduct an extensive inventory of KNOX proteins across diverse plant species.
• To investigate the evolutionary relationships and expression patterns of KNOX proteins, focusing on functional diversification.
• To analyze the expansion of KNOX gene families in specific species like Glycine max.

Main Methods:

• Comprehensive protein inventory across 48 plant species.
• Phylogenetic analysis to classify KNOX proteins into classes I and II and compare with green algae homologs.
• Analysis of public gene expression data, particularly in Glycine max, to determine expression patterns and tissue specificity.

Main Results:

• A total of 394 KNOX proteins were identified from 48 species, with land plant proteins falling into classes I and II.
• KNATM proteins are exclusive to Eudicots, and some species exhibit multiple paralogs.
• Glycine max shows a significant increase in KNOX paralogs; class II proteins have broad expression, class I proteins are axis-specific, and KNATM paralogs show low expression, highest in the early plumular axis.

Conclusions:

• The expansion of KNOX gene numbers is linked to functional diversification, as evidenced by expression patterns in Glycine max.
• Class I KNOX proteins show conserved roles in axis tissues, while KNATM proteins may have specialized functions in Eudicots.
• This study provides a comprehensive overview of KNOX protein evolution and function across land plants.