title: BLADE-ON-PETIOLE genes: setting boundaries in development and defense.
abstract: BLADE-ON-PETIOLE (BOP) genes encode an ancient and conserved subclade of BTB-ankryin transcriptional co-activators, divergent in the NPR1 family of plant defense regulators. Arabidopsis BOP1/2 were originally characterized as regulators of leaf and floral patterning. Recent investigation of BOP activity in a variety of land plants provides a more complete picture of their conserved functions at lateral organ boundaries in the determination of leaf, flower, inflorescence, and root nodule architecture. BOPs exert their function in part through promotion of lateral organ boundary genes including ASYMMETRIC LEAVES2, KNOTTED1-LIKE FROM ARABIDOPSIS6, and ARABIDOPSIS THALIANA HOMEOBOX GENE1 whose products restrict growth, promote differentiation, and antagonize meristem activity in various developmental contexts. Mutually antagonistic interactions between BOP and meristem factors are important in maintaining a border between meristem-organ compartments and in controlling irreversible transitions in cell fate associated with differentiation. We also examine intriguing new evidence for BOP function in plant defense. Comparisons to NPR1 highlight previously unexplored mechanisms for co-ordination of development and defense in land plants.
authors.affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Madiha
authors.initials: M
authors.lastname: Khan
authors.affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Huasong
authors.initials: H
authors.lastname: Xu
authors.affiliation: Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6. Electronic address: shelley_hepworth@carleton.ca.
authors.forename: Shelley R
authors.initials: SR
authors.lastname: Hepworth
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D060467:Disease Resistance / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018519:Meristem / Q000378:metabolism*; D063245:Plant Development / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; C496963:BOP1 protein, Arabidopsis
keywords: Abscission; BLADE-ON-PETIOLE; BTB-ankryin; Defense; Development; Lateral organ boundaries