GSE61333
Zea mays Transcriptome or Gene expression
Development of multicellular organisms proceeds via the correct interpretation of positional information to establish boundaries that separate developmental fields with distinct identities. The maize 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. Specialised 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 utilized laser-microdissection RNAseq to identify genes that are differentially expressed along 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 mutant leaf primordia. We identified transcripts that are specifically upregulated at the blade-sheath boundary. A surprising number of these ligule genes are also implicated to function during leaf initiation or lateral branching, and intersect multiple hormonal signalling pathways. We propose that genetic modules utilised in leaf and/or branch initiation are redeployed to regulate ligule outgrowth from leaf primordia. Overall design: In this study, we analysed the transcriptome associated with ligule formation using laser microdissection RNA-sequencing (LM-RNAseq). We quantified transcript accumulation in the PLB and adjacent pre-blade and pre-sheath regions of wild-type leaf primordia in order to identify candidate genes involved in proximal-distal patterning at the blade-sheath boundary. We also compared transcript accumulation in lg1-R mutants and wild-type siblings to identity genes acting downstream of LG1.