title: EctopicKNOXExpression Affects Plant Development by Altering Tissue Cell Polarity and Identity.
abstract: Plant development involves two polarity types: tissue cell (asymmetries within cells are coordinated across tissues) and regional (identities vary spatially across tissues) polarity. Both appear altered in the barley (Hordeum vulgare)Hoodedmutant, in which ectopic expression of theKNOTTED1-like Homeobox(KNOX) gene,BKn3, causes inverted polarity of differentiated hairs and ectopic flowers, in addition to wing-shaped outgrowths. These lemma-specific effects allow the spatiotemporal analysis of events following ectopicBKn3expression, determining the relationship between KNOXs, polarity, and shape. We show that tissue cell polarity, based on localization of the auxin transporter SISTER OF PINFORMED1 (SoPIN1), dynamically reorients as ectopicBKn3expression increases. Concurrently, ectopic expression of the auxin importerLIKE AUX1and boundary geneNO APICAL MERISTEMis activated. The polarity of hairs reflects SoPIN1 patterns, suggesting that tissue cell polarity underpins oriented cell differentiation. Wing cell files reveal an anisotropic growth pattern, and computational modeling shows how polarity guiding growth can account for this pattern and wing emergence. The inverted ectopic flower orientation does not correlate with SoPIN1, suggesting that this form of regional polarity is not controlled by tissue cell polarity. Overall, the results suggest that KNOXs trigger different morphogenetic effects through interplay between tissue cell polarity, identity, and growth.
authors.affiliation: Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
authors.forename: Annis
authors.identifier: http://orcid.org/0000-0002-2061-4902
authors.initials: A
authors.lastname: Richardson
authors.affiliation: Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom.
authors.forename: Alexandra B
authors.initials: AB
authors.lastname: Rebocho
authors.affiliation: Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom enrico.coen@jic.ac.uk.
authors.forename: Enrico
authors.identifier: http://orcid.org/0000-0001-8454-8767
authors.initials: E
authors.lastname: Coen