title: YUCCAauxin biosynthetic genes are required for Arabidopsis shade avoidance.
abstract: Plants respond to neighbor shade by increasing stem and petiole elongation. Shade, sensed by phytochrome photoreceptors, causes stabilization ofPHYTOCHROME INTERACTING FACTORproteins and subsequent induction ofYUCCAauxin biosynthetic genes. To investigate the role ofYUCCAgenes in phytochrome-mediated elongation, we examined auxin signaling kinetics after an end-of-day far-red (EOD-FR) light treatment, and found that an auxin responsive reporter is rapidly induced within 2 hours of far-red exposure.YUCCA2, 5, 8,and9are all induced with similar kinetics suggesting that they could act redundantly to control shade-mediated elongation. To test this hypothesis we constructed ayucca2, 5, 8, 9quadruple mutant and found that the hypocotyl and petiole EOD-FR and shade avoidance responses are completely disrupted. This work shows thatYUCCAauxin biosynthetic genes are essential for detectable shade avoidance and thatYUCCAgenes are important for petiole shade avoidance.
authors.affiliation: Department of Plant Biology, University of California , Davis , CA , United States.
authors.forename: Patricia
authors.initials: P
authors.lastname: Müller-Moulé
authors.affiliation: Department of Plant Biology, University of California , Davis , CA , United States.
authors.forename: Kazunari
authors.initials: K
authors.lastname: Nozue
authors.affiliation: Department of Plant Biology, University of California, Davis, CA, United States; PASCO Scientific, Roseville, CA, United State of America.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Pytlak
authors.affiliation: Department of Plant Biology, University of California, Davis, CA, United States; Natural Sciences Department, Castleton University, Castleton, VT, United States.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Palmer
authors.affiliation: Department of Plant Biology, University of California, Davis, CA, United States; Amaryllis Nucleics, Berkeley, CA, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Covington
authors.affiliation: Department of Plant Biology, University of California, Davis, CA, United States; Clontech Laboratories, Mountain View, CA, United States.
authors.forename: Andreah D
authors.initials: AD
authors.lastname: Wallace
authors.affiliation: Department of Plant Biology, University of California , Davis , CA , United States.
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Harmer
authors.affiliation: Department of Plant Biology, University of California , Davis , CA , United States.
authors.forename: Julin N
authors.initials: JN
authors.lastname: Maloof
keywords: Auxin; Photomorphogenesis; Phytochrome; Shade avoidance