Biology subjects

Van Norman, J. M.

Publications and source records attributed to Van Norman, J. M..

7 recordsLinked to original sources

bioRxiv2025

WALLFLOWER, an Arabidopsis receptor-like kinase, is polarized in root epidermal cells where it represses cell elongation impacting root waving

Precise control of cell elongation and changes in directional growth are required for adaptive root responses. Anisotropic cell expansion in the roots longitudinal axis must be coordinated among adjacent cell files and throughout the radial axis. However, links between activities across developmental axes remain obscure. We identified WALLFLOWER (WFL), a transmembrane receptor-like kinase that accumulates at the inner polar domain of epidermal cells in the root elongation zone. wfl mutants show deeper root waves and altered response to gravitropic re-orientation with increased cell length in specific root epidermal cell files. wfl phenotypes are rescued by WFL-GFP, but not by an intracellular truncation of WFL, which unexpectedly accumulates at the opposite (outer) polar domain. This suggests WFL function and its localization to the inner lateral plasma membrane domain are tightly coupled. Using advanced imaging techniques, including lifetime and atomic force microscopy, we found several mechano-chemical aspects of the wfl outer and inner cell walls are altered. This is consistent with a function for WFL in maintaining balanced mechanical properties between lateral cell walls during expansion. Overall, this work establishes a clear link between lateral protein polarization in peripheral tissues and longitudinal cell expansion required for adaptive organ growth.

plant biology↗

bioRxiv2024

Sucrose-responsive osmoregulation of plant cell size by a long non-coding RNA

The shoot of green plants is the primary site of carbon assimilation into sugars, the key source of energy and metabolic building blocks. The systemic transport of sugars is essential for plant growth and morphogenesis. Plants evolved intricate networks of molecular players to effectively orchestrate the subcellular partitioning of sugars. Dynamic distribution of these osmotically active compounds is a handy tool to regulate cell turgor pressure. Pressure-induced mechanical forces play an instructive role in developmental biology across kingdoms. Here, we functionally characterized a long non-coding RNA, CARMA, as a negative regulator of a receptor-like kinase, CANAR. Sugar-responsive CARMA specifically fine-tunes CANAR expression in the phloem, the route of sugar transport. By controlling sugar distribution, the CARMA-CANAR module allows cells to flexibly adapt to the external osmolality and adjust the size of vascular cell types during organ growth and development. We identify a nexus of plant vascular tissue formation with cell internal pressure monitoring and reveal a novel functional aspect of long non-coding RNAs in developmental biology.

plant biology↗

bioRxiv2023

Radial askew endodermal cell divisions reveal IRK functions in division orientation

Oriented cell divisions establish plant tissue and organ patterning and produce different cell types; this is particularly true of the highly organized Arabidopsis root meristem. Mutant alleles of INFLORESCENCE AND ROOT APICES RECEPTOR KINASE (IRK) exhibit excess cell divisions in the root endodermis. IRK is a transmembrane receptor kinase that localizes to the outer polar domain of these cells, which suggests directional signal perception is necessary to repress endodermal cell division. Here, a detailed examination revealed many of the excess endodermal divisions in irk have division planes that specifically skew towards the outer lateral side, therefore we termed them radial askew divisions. Expression of an IRK truncation, lacking the kinase domain, retains polar localization and rescues these radial askew divisions, but the roots exhibit excess periclinal endodermal divisions. Using markers of cell identity, we show that the daughters of radial askew divisions transition from endodermal to cortex identity similar to those of periclinal divisions. These results extend the requirement for IRK beyond repression of cell division activity to include cell division plane positioning. Based on its polarity, we propose that IRK at the outer lateral endodermal cell face participates in division plane positioning to ensure normal root ground tissue patterning.

plant biology↗

bioRxiv2023

WALLFLOWER, a RLK, simultaneously localizes to opposite sides of root hair cells & functions to position hairs

Polarized cells are frequently partitioned into subdomains with unique features or functions. As plant cells are surrounded by walls, polarized cell shape and protein polarity in the plasma membrane are particularly important for normal physiology and development. We have identified WALLFLOWER (WFL), a transmembrane receptor kinase that is asymmetrically distributed at the inner face of epidermal cells and this localization is maintained independent of cell type. In epidermal hair (H) cells in the elongation and differentiation zones, WFL exhibits a dual polar localization, accumulating at the inner domain as well as at the root hair initiation domain (RHID). Furthermore, overexpression of WFL leads to a downward shift in root hair (RH) position suggesting WFL operates in a signaling pathway that functions across H cells to inform RH position. WFL asymmetric distribution and function is affected by deletion of the intracellular domains resulting in its mislocalization to the outer polar domain of H cells and exclusion from RHIDs and bulges. Thus, our results demonstrate that in epidermal H cells the WFL intracellular domains are required to direct its dual polar localization and influence RH position. ONE SENTENCE SUMMARYA receptor kinase with dual polar localization, to the inner polar domain and root hair initiation domain, in root epidermal cells, requires its intracellular domain for localization and function.

plant biology↗

bioRxiv2021

A G-lectin Receptor Kinase is a Negative Regulator of Arabidopsis Immunity Against Root-Knot Nematode Meloidogyne incognita

Root-knot nematodes (Meloidogyne spp., RKN) are responsible for extensive crop losses worldwide. For infection, they penetrate plant roots, migrate between plant cells, and establish feeding sites, known as giant cells, in the root pericycle. Previously, we found that nematode perception and early plant responses were similar to those for microbial pathogens and require the BAK1 co-receptor in Arabidopsis thaliana and tomato. To identify additional receptors involved in this process, we implemented a reverse genetic screen for resistance or sensitivity to RKN using Arabidopsis T-DNA alleles of genes encoding transmembrane receptor-like kinases. This screen identified a pair of allelic mutations with enhanced resistance to RKN in a gene we named ENHANCED RESISTANCE TO NEMATODES 1 (ERN1). ERN1 encodes a G-type lectin receptor kinase (G-LecRK) with a single pass transmembrane domain. Further characterization showed that ern1 mutants displayed stronger activation of MAP kinases, elevated levels of the defense marker MYB51, and enhanced H202 accumulation in roots upon RKN elicitor treatments. Elevated MYB51 expression and ROS burst were also observed in leaves of ern1 mutants upon flg22 treatment. Complementation of ern1.1 with 35S- or native promotor-driven ERN1 rescued the RKN infection and enhanced defense phenotypes. Taken together, our results indicate that ERN1 is an important negative regulator of immunity. One sentence summaryA plasma membrane localized G-lectin receptor kinase acts as a negative immune regulator by interfering with defense responses activated by nematode and microbial elicitors.

plant biology↗

bioRxiv2021

Polarly localized receptor-like kinases PXC2 and IRK act redundantly during Arabidopsis root development in the radial axis

Coordination of cell division and differentiation is critical for tissue patterning during organ development. Directional signaling and cell polarity have important roles in coordination of these processes. For instance, the Arabidopsis receptor-like kinase INFLORESCENCE AND ROOT APICES KINASE (IRK) functions to restrict stele area and repress longitudinal anticlinal divisions (LADs) in the endodermis where it is polarly localized. IRK is closely related to PXY/TDR CORRELATED 2 (PXC2); here, we show that PXC2 exhibits similar polarized accumulation suggesting they have related functions. pxc2 roots have increased stele area and irk pxc2 double mutant roots show increases in stele area and endodermal LADs beyond either single mutant, indicating that polarly localized IRK and PXC2 function redundantly to repress endodermal LADs and stele area. The double mutant also exhibits agravitropic root growth and abnormal cotyledon vein patterning. Manipulation of PIN1 trafficking and (re)localization mechanisms indicate that PXC2 and/or IRK suggest a link to modulation of polar auxin transport. We conclude that IRK and PXC2 have partially redundant functions in the root, but may have independent functions that are tissue-specific. We propose that repression of endodermal LADs and stele area through a PXC2/IRK-mediated, directional signaling pathway is required for normal ground tissue cell divisions, tissue patterning, and growth in Arabidopsis roots.

plant biology↗

bioRxiv2020

A series of dual-reporter vectors for ratiometric analysis of protein abundance in plants

Ratiometric reporter systems enable comparisons of the abundance of a protein of interest, or "target," relative to a reference protein. Both proteins are encoded on a single transcript but are separated during translation. This arrangement bypasses the potential for discordant expression that can arise when the target and reference proteins are encoded by separate genes. We generated a set of 18 Gateway-compatible vectors termed pRATIO that combine a variety of promoters, fluorescent and bioluminescent reporters, and 2A "self-cleaving" peptides. These constructs are easily modified to produce additional combinations or introduce new reporter proteins. We found that mScarlet-I provides the best signal-to-noise ratio among several fluorescent reporter proteins during transient expression experiments in Nicotiana benthamiana. Firefly and Gaussia luciferase also produce high signal-to-noise in N. benthamiana. As proof of concept, we used this system to investigate whether degradation of the receptor KAI2 after karrikin treatment is influenced by its subcellular localization. KAI2 is normally found in the cytoplasm and the nucleus of plant cells. In N. benthamiana, karrikin-induced degradation of KAI2 was only observed when it was retained in the nucleus. These vectors are tools to easily monitor in vivo the abundance of a protein that is transiently expressed in plants, and will be particularly useful for investigating protein turnover in response to different stimuli.

plant biology↗