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Title: Control of Arabidopsis leaf morphogenesis through regulation of the YABBY and KNOX families of transcription factors

Author
item HA, CHAN - University Of California
item JUN, JI - University Of California
item Fletcher, Jennifer

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2010
Publication Date: 9/1/2010
Citation: Ha, C.M., Jun, J.H., Fletcher, J.C. 2010. Control of Arabidopsis leaf morphogenesis through regulation of the YABBY and KNOX families of transcription factors. Genetics. 186(1):197-206. Epub 2010 Jul 6.

Interpretive Summary: The proper formation of leaves is fundamental for plant growth and development and is under strict genetic control. Arabidopsis plants lacking the activity of the BLADE-ON-PETIOLE1 (BOP1) and BOP2 genes form leaves that have extra tissue at their base. This article reports that two unrelated groups of genes, the YABBY and KNOX genes, are required for the production of the extra leaf tissue. We find that the YABBY genes play a more important role in this process than the KNOX genes. We conclude that BOP1 and BOP2 control leaf formation by repressing both YABBY and KNOX activity at the leaf base. Our findings increase our understanding of the leaf patterning process and suggest new ways to manipulate leaf biomass in other plant species.

Technical Abstract: The patterning of initiating organs along specific axes of polarity is critical for the proper development of all higher organisms. Plant lateral organs, such as leaves, are derived from the shoot apical meristems located at the growing tips. After initiation, the leaf primordia of species such as Arabidopsis thaliana differentiate into a polarized structure consisting of a proximal petiole and a distal blade, but the molecular mechanisms that control proximal-distal pattern formation are poorly understood. The transcriptional activators BLADE-ON-PETIOLE1 (BOP1) and BOP2 are known to control Arabidopsis lateral organ differentiation by regulating gene expression along the adaxial-abaxial (dorsal-ventral) and proximal-distal polarity axes. Here, we demonstrate that the development of ectopic blade tissue along bop1 bop2 leaf petioles is strongly suppressed in a dosage-dependant manner by mutations in either of two closely related YABBY (YAB) genes, FILAMENTOUS FLOWER (FIL) and YAB3. Three KNOTTED-LIKE HOMEOBOX (KNOX1) genes also make lesser, and partially redundant, contributions to ectopic blade development in bop1 bop2 leaves. Mutation of these YAB and KNOX1 genes together causes nearly complete suppression of bop1 bop2 ectopic organ outgrowth at the morphological and cellular levels. Our data demonstrate that BOP1 and BOP2 regulate leaf patterning by controlling YAB and KNOX1 gene activity in the developing petiole.