title: Transcriptomic analyses indicate that maize ligule development recapitulates gene expression patterns that occur during lateral organ initiation.
abstract: Development of multicellular organisms proceeds via the correct interpretation of positional information to establish boundaries that separate developmental fields with distinct identities. The maize (Zea mays) leaf is an ideal system to study plant morphogenesis as it is subdivided into a proximal sheath and a distal blade, each with distinct developmental patterning. Specialized ligule and auricle structures form at the blade-sheath boundary. The auricles act as a hinge, allowing the leaf blade to project at an angle from the stem, while the ligule comprises an epidermally derived fringe. Recessive liguleless1 mutants lack ligules and auricles and have upright leaves. We used laser microdissection and RNA sequencing to identify genes that are differentially expressed in discrete cell/tissue-specific domains along the proximal-distal axis of wild-type leaf primordia undergoing ligule initiation and compared transcript accumulation in wild-type and liguleless1-R mutant leaf primordia. We identified transcripts that are specifically upregulated at the blade-sheath boundary. A surprising number of these "ligule genes" have also been shown to function during leaf initiation or lateral branching and intersect multiple hormonal signaling pathways. We propose that genetic modules utilized in leaf and/or branch initiation are redeployed to regulate ligule outgrowth from leaf primordia.
authors.affiliation: Section of Plant Biology, Cornell University, Ithaca, New York 14853.
authors.forename: Robyn
authors.initials: R
authors.lastname: Johnston
authors.affiliation: Computational Biology Service Unit, Cornell University, Ithaca, New York 14853.
authors.forename: Minghui
authors.initials: M
authors.lastname: Wang
authors.affiliation: Computational Biology Service Unit, Cornell University, Ithaca, New York 14853.
authors.forename: Qi
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Department of Developmental Genetics, University of Wyoming, Laramie, Wyoming 82071.
authors.forename: Anne W
authors.initials: AW
authors.lastname: Sylvester
authors.affiliation: Plant Gene Expression Center, U.S. Department of Agriculture-Agricultural Research Service, Plant and Microbial Biology Department, University of California at Berkeley, Berkeley, California 94720.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hake
authors.affiliation: Section of Plant Biology, Cornell University, Ithaca, New York 14853 mjs298@cornell.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Scanlon
mesh_terms: D019295:Computational Biology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D003313:Zea mays / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development
chemical_list: D012333:RNA, Messenger