Maize leaves have distinct tissues that serve specific purposes. The blade tilts back to photosynthesize and the sheath wraps around the stem to provide structural support and protect young leaves. At the junction between blade and sheath are the ligule and auricles, both of which are absent in the recessive liguleless1 (lg1) mutant. Using an antibody against LG1, we reveal LG1 accumulation at the site of ligule formation and in the axil of developing tassel branches. The dominant mutant Wavy auricle in blade1 (Wab1-R) produces ectopic auricle tissue in the blade and increases the domain of LG1 accumulation. We determined that wab1 encodes a TCP transcription factor by positional cloning and revertant analysis. Tassel branches are few and upright in the wab1 revertant tassel and have an increased branch angle in the dominant mutant. wab1 mRNA is expressed at the base of branches in the inflorescence and is necessary for LG1 expression. wab1 is not expressed in leaves, except in the dominant mutant. The domain of wab1 expression in the Wab1-R leaf closely mirrors the accumulation of LG1. Although wab1 is not needed to induce lg1 expression in the leaf, LG1 is needed to counteract the severe phenotype of the dominant Wab1-R mutant. The regulatory interaction of LG1 and WAB1 reveals a link between leaf shape and tassel architecture, and suggests the ligule is a boundary similar to that at the base of lateral organs.

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Choanoflagellates offer key insights into bacterial influences on the origin and early evolution of animals. Here we report the isolation and characterization of a new colonial choanoflagellate species, Salpingoeca monosierra, that, unlike previously characterized species, harbors a stable microbiome. S. monosierra was isolated from Mono Lake, California and forms large spherical colonies that are more than an order of magnitude larger than those formed by the closely related S. rosetta. By designing fluorescence in situ hybridization probes from metagenomic sequences, we found that S. monosierra colonies are colonized by members of the halotolerant and closely related Saccharospirillaceae and Oceanospirillaceae, as well as purple sulfur bacteria (Ectothiorhodospiraceae) and non-sulfur Rhodobacteraceae. This relatively simple microbiome in a close relative of animals presents a new experimental model for investigating the evolution of stable interactions among eukaryotes and bacteria.

We introduce a cost-effective and easily implemented scan unit which enables any camera-based microscope to perform projection imaging from diverse viewing angles. We demonstrate this capability on Lattice Light-Sheet and Oblique Plane Microscopy by rapidly delivering projection images with an uncompromised lateral resolution and high optical contrast. By imaging the sample from one or multiple perspectives, our method enables visualization of rapid biological processes, real time stereoscopic imaging as well as three-dimensional particle localization throughout a cellular volume from just two images. Furthermore, because our projection imaging technique provides intuitive three-dimensional renderings in real-time, it improves microscope usability, allows users to more-readily optimize instrument performance and identify biological phenomena of interest on-the-fly, while also reducing data overhead by a factor of >100. We leverage our rapid projection method to image cancer cell morpho-dynamics and calcium signaling in cultured neurons, to perform three-dimensional localization of genetically encoded nanoparticles, as well as to image orthogonal views of an embryonic Zebrafish heart simultaneously.

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