Genetic Architecture of Meristem Morphological and Functional Diversity within the Genus Zea

Through combined organogenesis and maintenance of stem cell identity, the maize shoot apical meristem gives rise to all above-ground tissues found in the adult maize plant. Unlike the aerial tissues it produces, the shoot apical meristem of maize is difficult to observe during vegetative growth. Traditional methods of whole-meristem dissection or serial sectioning require high levels of skill, labor, and biological replication to accurately measure and examine intact shoot apical meristems. These limitations have slowed our understanding of maize meristem morphology and how it is correlated to important adult plant traits. By combining mathematical modeling of maize meristems as parabaloids and sensitive optical and x-ray observation (nanoCT) techniques, we have developed a semi-automated, higher-throughput phenotyping platform for characterizing morphological phenotypes in the shoot apical meristems of diverse maize lineages. Pilot studies of a diverse panel of maize inbreds identified candidate loci associated with shoot apical meristem shape and size by genome-wide association study (GWAS). Ongoing investigation of candidate loci aims to understand the genetic architecture and developmental regulation of this critical stem cell niche.