Search Results (7)

Plant glutamate receptor-like channels (GLRs) are homologs of animal ionotropic glutamate receptors. GLRs are critical in various plant biological functions, yet their genomic features and functions in disease resistance remain largely unknown in many crop species. Here, we report the results on a thorough genome-wide study of the GLR family in oilseed rape (Brassica napus) and their role in resistance to the fungal pathogen Sclerotinia sclerotiorum. A total of 61 GLRs were identified in oilseed rape. They comprised three groups, as in Arabidopsis thaliana. Detailed computational analyses, including prediction of domain and motifs, cellular localization, cis-acting elements, PTM sites, and amino acid ligands and their binding pockets in BnGLR proteins, unveiled a set of group-specific characteristics of the BnGLR family, which included chromosomal distribution, motif composition, intron number and size, and methylation sites. Functional dissection employing virus-induced gene silencing of BnGLRs in oilseed rape and Arabidopsis mutants of BnGLR homologs demonstrated that BnGLR35/AtGLR2.5 positively, while BnGLR12/AtGLR1.2 and BnGLR53/AtGLR3.2 negatively, regulated plant resistance to S. sclerotiorum, indicating that GLR genes were differentially involved in this resistance. Our findings reveal the complex involvement of GLRs in B. napus resistance to S. sclerotiorum and provide clues for further functional characterization of BnGLRs. Full article

The systemic electrical signal propagation in plants (i.e., from leaf to leaf) is dependent on GLUTAMATE RECEPTOR-LIKE proteins (GLRs). The GLR receptors are the homologous proteins to the animal ionotropic glutamate receptors (iGluRs) which are ligand-gated non-selective cation channels that mediate neurotransmission in the animal’s nervous system. In this study, we investigated the effect of the general anaesthetic ketamine, a well-known non-competitive channel blocker of human iGluRs, on systemic electrical signal propagation in Arabidopsis thaliana. We monitored the electrical signal propagation, intracellular calcium level [Ca²⁺]_cyt and expression of jasmonate (JA)-responsive genes in response to heat wounding. Although ketamine affected the shape and the parameters of the electrical signals (amplitude and half-time, t_1/2) mainly in systemic leaves, it was not able to block a systemic response. Increased [Ca²⁺]_cyt and the expression of jasmonate-responsive genes were detected in local as well as in systemic leaves in response to heat wounding in ketamine-treated plants. This is in contrast with the effect of the volatile general anaesthetic diethyl ether which completely blocked the systemic response. This low potency of ketamine in plants is probably caused by the fact that the critical amino acid residues needed for ketamine binding in human iGluRs are not conserved in plants’ GLRs. Full article

Ca²⁺ and H₂O₂ interact with each other to regulate plant systemic responses. However, their precise mechanism is not fully understood. A recent study revealed that the Ca²⁺ regulates the glycolate oxidase-catalase (GC) switch-mediated photorespiratory H₂O₂ during wounding. Glutamate-receptor-like (GLR) Ca²⁺ channels (GLR 3.3 and GLR3.6) are responsible for Ca²⁺ influx during injury for regulation of the GC switch. Mechanical injury quickly shifts the GC switch to a highly interactive state in the systemic leaves that ultimately results in the reduced peroxisomal H₂O₂. However, the mechanism of H₂O₂ reduction in peroxisome remains elusive. Full article

Plant glutamate receptor-like channels (GLRs) are the homologues of ionotropic glutamate receptors (iGluRs) that mediate neurotransmission in mammals, and they play important roles in various plant-specific physiological processes, such as pollen tube growth, sexual reproduction, root meristem proliferation, internode cell elongation, stomata aperture regulation, and innate immune and wound responses. Notably, these biological functions of GLRs have been mostly linked to the Ca²⁺-permeable channel activity as GLRs can directly channel the transmembrane flux of Ca²⁺, which acts as a key second messenger in plant cell responses to both endogenous and exogenous stimuli. Thus, it was hypothesized that GLRs are mainly involved in Ca²⁺ signaling processes in plant cells. Recently, great progress has been made in GLRs for their roles in long-distance signal transduction pathways mediated by electrical activity and Ca²⁺ signaling. Here, we review the recent progress on plant GLRs, and special attention is paid to recent insights into the roles of GLRs in response to environmental stimuli via Ca²⁺ signaling, electrical activity, ROS, as well as hormone signaling networks. Understanding the roles of GLRs in integrating internal and external signaling for plant developmental adaptations to a changing environment will definitely help to enhance abiotic stress tolerance. Full article

Glutamate receptors (GLRs) are involved in multiple functions during the plant life cycle through affecting the Ca²⁺ concentration. However, GLRs in Brassica species have not yet been reported. In this study, 16 glutamate receptor-like channels (GLR) belonged to two groups were identified in the Brassica rapa (B. rapa) genome by bioinformatic analysis. Most members contain domains of ANF_receptor, Peripla_BP_6, Lig_chan, SBP_bac_3, and Lig_chan_Glu_bd that are closely related to glutamate receptor channels. This gene family contains many elements associated with drought stress, low temperature stress, methyl jasmonate (MeJA), salicylic acid (SA), and other stress resistance. Gene expression profiles showed that BraGLR genes were expressed in roots, stems, leaves, flowers, and siliques. BraGLR5 expression was elevated after drought stress in drought-sensitive plants. BraGLR1, BraGLR8, and BraGLR11 expression were significantly upregulated after salt stress. BraGLR3 expression is higher in the female sterile-line mutants than in the wild type. The expression levels of BraGLR6, BraGLR9, BraGLR12, and BraGLR13 were significantly higher in the male sterile-line mutants than in the wild type. The expression of most BraGLRs increased after self-pollination, with BraGLR9 exhibiting the greatest increase. These results suggest that BraGLRs play an important role in abiotic stress tolerance and sexual reproduction. Full article

Occurrence of tipburn is a severe problem in the production of lisianthus cultivars. Previous studies have shown excessive Ca accumulation in the roots of tipburn-damaged cultivars, where the distribution of Ca to the tips of the top leaves is inhibited. However, few studies have investigated the association between Ca accumulation and gene expression in horticultural crops. To provide a list of candidate target genes that might be causing the excessive Ca accumulation in roots, we focused Ca²⁺ transporter and pectin methylesterase (PME) genes and RNA-seq of upper leaves and roots in tipburn-occurrence cultivar (“Voyage peach”: VP) and non-occurrence cultivar (“Umi honoka”: UH) was conducted. In both the upper leaves and roots of VP, genes encoding the glutamate receptors (GLRs), cation/Ca²⁺ exchangers 4 (CCX4), Na⁺/Ca²⁺ exchanger-like protein (NCL), and PMEs were upregulated, and a gene encoding the cyclic nucleotide-gated ion channel 9 (CNGC9) was downregulated. In contrast, genes encoding the vacuolar cation/proton exchanger 5 (CAX5), calcium-transporting ATPase 1 and 12 (ACA1 and ACA12) showed differential expression in each organ. Among them, only CAX5 was upregulated and ACA12 was downregulated in the roots of VP. Based on these results, we suggested that CAX5 and ACA12 are the candidate genes causing the excessive Ca accumulation in the roots of tipburn-occurrence lisianthus cultivars. Future studies should investigate the temporal changes in gene expression using quantitative PCR and conduct functional analysis of candidate genes in tipburn-damaged lisianthus cultivars. Full article

Calcium (Ca²⁺) plays a critical role in the regulation of growth and development and environmental stress responses in plants. The membrane-associated Ca²⁺ transport proteins are required to mediate Ca²⁺ signaling and maintain Ca²⁺ homeostasis. Ca²⁺ channels, pumps (ATPases), and antiporters are three major classes of Ca²⁺ transporters. Although the genome-wide analysis of Ca²⁺ transporters in model plants Arabidopsis and rice have been well documented, the identification, classification, phylogenesis, expression profiles, and physiological functions of Ca²⁺ transport proteins in soybean are largely unknown. In this study, a comprehensive in silico analysis of gene families associated with Ca²⁺ transport was conducted, and a total of 207 putative Ca²⁺ transporter genes have been identified in soybean. These genes belong to nine different families, such as Ca²⁺-ATPase, Ca²⁺/cation antiporter, cyclic nucleotide-gated ion channel (CNGC), and hyperosmolality induced cytosolic Ca²⁺ concentration channel (OSCA). Detailed analysis of these identified genes was performed, including their classification, phylogenesis, protein domains, chromosomal distribution, and gene duplication. Expression profiling of these genes was conducted in different tissues and developmental stages, as well as under stresses using publicly available RNA-seq data. Some genes were found to be predominantly expressed in specific tissues like flowers and nodules, and some genes were found to be expressed strongly during seed development. Seventy-four genes were found to be significantly and differentially expressed under abiotic and biotic stresses, such as salt, phosphorus deficiency, and fungal pathogen inoculation. In addition, hormonal signaling- and stress response-related cis-elements and potential microRNA target sites were analyzed. This study suggests the potential roles of soybean Ca²⁺ transporters in stress responses and growth regulation, and provides a basis for further functional characterization of putative Ca²⁺ transporters in soybean. Full article