Organ-specific genetic interactions between paralogues of the PXY and ER receptor kinases enforce radial patterning in Arabidopsis vascular tissue.

In plants, cells do not migrate. Tissues are frequently arranged in concentric rings; thus, expansion of inner layers is coordinated with cell division and/or expansion of cells in outer layers. In Arabidopsis stems, receptor kinases, PXY and ER, genetically interact to coordinate vascular proliferation and organisation via inter-tissue signalling. The contribution of PXY and ER paralogues to stem patterning is not known, nor is their function understood in hypocotyls, which undergo considerable radial expansion. Here, we show that removal of all PXY and ER gene-family members results in profound cell division and organisation defects. In hypocotyls, these plants failed to transition to true radial growth. Gene expression analysis suggested that PXY and ER cross- and inter-family transcriptional regulation occurs, but it differs between stem and hypocotyl. Thus, PXY and ER signalling interact to coordinate development in a distinct manner in different organs. We anticipate that such specialised local regulatory relationships, where tissue growth is controlled via signals moving across tissue layers, may coordinate tissue layer expansion throughout the plant body.

Versatile method for quantifying and analyzing morphological differences in experimentally obtained images.

Analyzing high-resolution images to gain insight into anatomical properties is an essential tool for investigation in many scientific fields. In plant biology, studying plant phenotypes from micrographs is often used to build hypotheses on gene function. In this report, we discuss a bespoke method for inspecting the significance in the differences between the morphologies of several plant mutants at cellular level. By examining a specific example in the literature, we will detail the approach previously used to quantify the effects of two gene families on the vascular development of hypocotyls in Arabidopsis thaliana. The method incorporates a MATLAB algorithm and statistical tools which can be modified and enhanced to tailor to different research questions in future studies.

Connections in the cambium, receptors in the ring.

In plants, pluripotent cells in meristems divide to provide cells for the formation of postembryonic tissues. The cambium is the meristem from which the vascular tissue is derived and is the main driver for secondary (radial) growth in dicots. Xylem and phloem are specified on opposing sides of the cambium, and tightly regulated cell divisions ensure their spatial separation. Peptide ligands, phytohormones, and their receptors are central to maintaining this patterning and regulating proliferation. Here, we describe recent advances in our understanding of how these signals are integrated to control vascular development and secondary growth.