Nonreciprocal complementation of KNOX gene function in land plants

Area of Science:

• Plant developmental biology
• Evolutionary genetics
• Molecular evolution

Background:

• Class I KNOTTED-LIKE HOMEOBOX (KNOX) proteins are crucial for sporophyte development in diverse land plants.
• The functional evolution of Class I KNOX genes across plant lineages remains incompletely understood.

Purpose of the Study:

• To investigate the evolutionary modifications of Class I KNOX gene function during land plant evolution.
• To understand the divergence of KNOX gene families and their roles in different plant groups.

Main Methods:

• Phylogenetic analyses of Class I KNOX proteins.
• Cross-species complementation assays using plant mutants and genes from various species (mosses, lycophytes, ferns, flowering plants).

Main Results:

• A gene duplication in charophytes created distinct Class I and Class II KNOX families.
• Moss Class I KNOX sequences are similar to vascular plant orthologs but exhibit broader functional capacity.
• The moss gene PpMKN2 and lycophyte KNOX genes complemented the Arabidopsis bp-9 mutant, while fern genes showed partial complementation.

Conclusions:

• Moss KNOX proteins possess a broader developmental function compared to vascular plant counterparts.
• The functional scope of Class I KNOX proteins narrowed progressively during the divergence of lycophytes, ferns, and flowering plants.
• Evolutionary changes in KNOX-interacting BELL proteins correlate with KNOX functional divergence.