A collaborative project with the Anne Sylvester (Cornell U), Andrew Nelson (Boyce Thompson Institute), and Robert Schmitz (U. Georgia).
Establishing organ boundaries is essential to plant development and directly impacts plant architecture. Without correct establishment of boundaries for organ initiation, plant shape and ultimately function is affected. In the maize leaf, proximal distal patterning involves formation of the easily accessible ligule/auricle boundary between the proximal sheath and the distal blade. Our previous project generated candidate genes that are significantly expressed in this ligule/auricle region as well as other organ boundaries. These observations suggest that common mechanisms are utilized to initiate leaves and branches are redeployed to regulate ligule and auricle development from leaf primordia. A major step in understanding morphogenesis of these structures requires knowing when and how the auricle forms relative to the ligule. The process is spatially and temporally constrained, thereby demanding analysis of the process at single cell resolution. Live cell-imaging of maize reporter-fusion proteins will generate a developmental timeline of auricle initiation and outgrowth relative to ligule morphogenesis during three stages of ontogeny in wild-type and liguless/auricleless mutant maize shoots. Analyses of wild-type and mutant maize seedlings by scRNA-seq will identify cell-specific genes and gene networks at three stages of ligule/auricle ontogeny. Single-cell Assay for Transposase Accessible Chromatin sequencing (scATAC-seq) will identify shared and unique CRE and their associated transcription factors during ligule/auricle differentiation and growth in wild-type and mutant maize seedlings at three developmental stages. Machine Learning approaches will be employed to synthesize and correlate the cellular, transcriptomic, and chromatin accessibility data generated during this proposal. The outcomes will allow us to select candidate genes for functional analyses of cell-fate acquisition and outgrowth of the maize ligule/auricle.