ABSTRACT: In this study we used the maize (Zea mays) inflorescence to investigate gene networks that modulate determinacy, specifically the decision to allow branch growth. We characterized developmental transitions by associating spatiotemporal expression profiles with morphological changes resulting from genetic perturbations that disrupt steps in a pathway controlling branching. These are the RNA-seq datasets used in this study. We profiled changes in gene expression during normal maize ear and tassel development and in developing maize ear primordia upon genetic perturbation of the RAMOSA branching pathway. For the wild-type ear and tassel developmental series, greenhouse-grown B73 inbred plants were used. 10mm ears were collected and sectioned as follows from tip to base along the developmental gradient: tip 1mm sampled (tip; Inflorescence Meristem/Spikelet Pair Meristem), next 1mm discarded, next 1mm sampled (mid; Spikelet Meristem), next 2mm discarded, next 2 mm sampled (base; Floral Meristem), and immediately frozen in liquid nitrogen. Sections from ~30 sampled ears were pooled for each of 2 biological replicates to represent tip, mid, and base stages. Tassels were hand-dissected, measured, separated by stage: 1-2mm (stg1), 3-4mm (stg2), and 5-7mm (stg3), and immediately frozen in liquid N. For each stage, ~20-30 tassels were pooled for each of 2 biological replicates. For ramosa mutant series, segregating families (1:1) of ra1-R, ra2-R, and ra3-fea1 mutant alleles, all introgressed at least 6 times into the B73 inbred background, were grown at CSHL Uplands Farm. Field-grown plants were genotyped and collected 6-7 weeks after germination (V7-V8 stage). First and second ear primordia were immediately hand-dissected, measured, and frozen in liquid nitrogen. For ra1, ra2 and ra3 mutants and wild-type controls, ears were pooled into two size classes: 1) 1mm class included a range of 0.7-1.5mm sized ears and nine ears were pooled for each of 2 biological replicates; 2) 2mm class included a range of 1.8-2.5mm sized ears and six ears were pooled for each of three biological replicates. Wild-type samples were proportional mixtures of heterozygote siblings segregating in ra1, ra2, and ra3 populations. Variability factors (e.g. ear size within class, ear rank on the plant, and time of collection) were distributed evenly across pooled samples.
