Biology subjects

Vukasinovic, N.

Publications and source records attributed to Vukasinovic, N..

5 recordsLinked to original sources

bioRxiv2025

Endocytosis of the damage-associated molecular pattern receptor PEPR1 is BAK1-dependent.

After cellular damage caused by wounding or pathogens, Arabidopsis thaliana endogenous elicitor peptides (Peps) are released into the apoplast, enhancing innate immunity by directly binding to the membrane-localized leucine-rich repeat receptor kinase PEP RECEPTOR1 (PEPR1). Ligand binding induces PEPR1 heterodimerization with the co-receptor BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1), followed by PEPR1 internalization, both essential for a subset of Pep1-induced responses. However, the role of BAK1 in Pep1-triggered PEPR1 endocytosis remains unclear. Here, we show that the ligand-induced PEPR1 endocytosis depends on its kinase activity and requires BAK1 C-terminal tail phosphorylation, which is equally indispensable for immune signaling and BAK1 internalization. Using a GFP insertional mutagenesis approach, we generated a partially functional GFP-tagged BAK1 to demonstrate that, following Pep1 elicitation, BAK1 and PEPR1 are endocytosed together with similar dynamics. Our findings identify the BAK1 function as a prerequisite for PEPR1 internalization.

plant biology↗

bioRxiv2024

The brassinosteroid receptor gene BRI1 safeguards cell-autonomous brassinosteroid signaling across tissues

Brassinosteroid signaling is essential for plant growth as exemplified by the dwarf phenotype of loss-of-function mutants in BRASSINOSTEROID INSENSITIVE 1 (BRI1), a ubiquitously expressed Arabidopsis brassinosteroid receptor gene. Complementation of brassinosteroid-blind receptor mutants by BRI1 expression with various tissue-specific promoters implied that local brassinosteroid signaling may instruct growth non-cell-autonomously. Here we performed such rescues with a panel of receptor variants and promoters, in combination with tissue-specific transgene knockouts. Our experiments demonstrate that brassinosteroid receptor expression in several tissues is necessary but not sufficient for rescue. Moreover, complementation with tissue-specific promoters requires the genuine BRI1 gene body sequence, which confers ubiquitous expression of trace receptor amounts that are sufficient to promote brassinosteroid-dependent root growth. Our data, therefore, argue for a largely cell-autonomous action of brassinosteroid receptors.

plant biology↗

bioRxiv2022

Brassinosteroid gene regulatory networks at cellular resolution

Brassinosteroids (BRs) are plant steroid hormones that regulate diverse processes such as cell division and cell elongation. BRs control thousands of genes through gene regulatory networks that vary in space and time. By using time-series single-cell RNA-sequencing to identify BR-responsive gene expression specific to different cell types and developmental stages of the Arabidopsis root, we uncovered the elongating cortex as a site where BRs trigger a shift from proliferation to elongation associated with increased expression of cell wall-related genes. Our analysis revealed HAT7 and GTL1 as BR-responsive transcription factors that regulate cortex cell elongation. These results establish the cortex as an important site for BR-mediated growth and unveil a BR signaling network regulating the transition from proliferation to elongation, illuminating new aspects of spatiotemporal hormone response.

plant biology↗

bioRxiv2022

Phosphorylation and ubiquitination independent endocytosis of BRI1

The brassinosteroid (BR) hormone and its plasma membrane receptor BR INSENSITIVE1 (BRI1) is one of the best-studied receptor-ligand pairs for understanding the interplay between receptor endocytosis and signaling in plants. BR signaling is mainly determined by the plasma membrane pool of BRI1, whereas BRI1 endocytosis ensures signal attenuation. Since BRs are ubiquitously distributed in the plant, the tools available to study BRI1 function without interference from endogenous BRs are limited. Here, we designed a BR-binding-deficient mutant based on protein sequence-structure analysis and homology modeling of BRI1 and its close homologues. This new tool allowed us to re-examine the BRI1 endocytosis and signal attenuation model. We show that despite decreased phosphorylation and ubiquitination, the BR-binding-deficient BRI1 was internalized similar to the wild type form. These results reinforce the hypothesis that BRI1 is internalized via parallel endocytic routes and machineries. In addition, BR-binding-deficient mutant provides opportunities to study non-canonical ligand-independent BRI1 functions.

plant biology↗

bioRxiv2020

Local brassinosteroid biosynthesis enables optimal root growth

Brassinosteroid hormones are indispensable for root growth and they control both cell division and cell elongation through the establishment of an increasing signaling gradient along the longitudinal root axis. Because of their limited mobility, the importance of brassinosteroid distribution for achieving the signaling maximum is largely overlooked. Expression pattern analysis of all known brassinosteroid biosynthetic enzymes revealed that not all cells in the Arabidopsis thaliana root possess full biosynthetic machinery and completion of biosynthesis relies on cell-to-cell movement of the hormone precursors. We demonstrate that brassinosteroid biosynthesis is largely restricted to the root elongation zone where it overlaps with brassinosteroid signaling maxima. Moreover, optimal root growth requires hormone concentrations, low in the meristem and high in the root elongation zone attributable to an increased biosynthesis. Our finding that spatiotemporal regulation of hormone synthesis results in a local hormone accumulation provides a paradigm for hormone-driven organ growth in the absence of long-distance hormone transport in plants.

plant biology↗