Decoding the features and potential roles of respiratory burst oxidase homologs in bread wheat

Identification of VcRBOH genes in blueberry and functional characterization of VcRBOHF in plant defense

Reactive oxygen species (ROS) serve as signal molecules in plant defense responses, and the respiratory burst oxidase homolog (RBOH) enzyme plays a crucial role in their production. Although numerous RBOH family members have been identified in various plants, little is known about the RBOH genes in blueberries. In this study, we identified six VcRBOH genes from the blueberry genome. Phylogenetic analysis revealed that these VcRBOH genes can be classified into three subgroups. Conserved domain and motif analysis demonstrated high sequence similarity among VcRBOH proteins. Analysis of cis-acting elements suggested that VcRBOH genes may be involved in stress, light, and phytohormone responsiveness. Based on transcriptome data, we observed low expression levels of VcRBOHB, VcRBOHC, and VcRBOHE during the flower_at_anthesis stage. In contrast, VcRBOHA and VcRBOHD showed relatively high expression levels in various tissues. The reverse-transcription quantitative PCR (RT-qPCR) analysis indicated rapid induction of VcRBOHF by flg22 and chitin treatments. Notably, overexpression of VcRBOHF in Arabidopsis promoted PTI responses, including increased expression of marker genes, ROS production, and callose deposition. Moreover, the overexpression of VcRBOHF resulted in enhanced disease resistance against Pseudomonas syringae pv. tomato (Pst) DC3000 infection. These findings provide valuable insights into the roles of VcRBOHF genes in plant defense responses and lay the groundwork for a more comprehensive understanding of the molecular mechanisms underpinning blueberry disease resistance.

Genome-Wide Identification, Classification, Expression Analysis, and Screening of Drought and Heat Resistance-Related Candidates of the Rboh Gene Family in Wheat

Plant respiratory burst oxidase homologs (Rbohs) are key enzymes that produce reactive oxygen species (ROS), which serve as signaling molecules regulating plant growth and stress responses. In this study, 39 TaRboh genes (TaRboh01-TaRboh39) were identified. These genes were distributed unevenly among the wheat genome's fourteen chromosomes, with the exception of homoeologous group 2 and 7 and chromosomes 4A, as well as one unidentified linkage group (Un). TaRbohs were classified into ten distinct clades, each sharing similar motif compositions and gene structures. The promoter regions of TaRbohs contained cis-elements related to hormones, growth and development, and stresses. Furthermore, five TaRboh genes (TaRboh26, TaRboh27, TaRboh31, TaRboh32, and TaRboh34) exhibited strong evolutionary conservation. Additionally, a Ka/Ks analysis confirmed that purifying selection was the predominant force driving the evolution of these genes. Expression profiling and qPCR results further indicated differential expression patterns of TaRboh genes between heat and drought stresses. TaRboh11, TaRboh20, TaRboh22, TaRboh24, TaRboh29, and TaRboh34 were significantly upregulated under multiple stress conditions, whereas TaRboh30 was only elevated in response to drought stress. Collectively, our findings provide a systematic analysis of the wheat Rboh gene family and establish a theoretical framework for our future research on the role of Rboh genes in response to heat and drought stress.

Genome-wide identification and expression analysis of ferric reductase oxidase (FRO) genes in Gossypium spp. reveal their crucial role in iron homeostasis under abiotic and biotic stress

Ferric Reductase Oxidase (FRO) genes are pivotal in iron uptake and homeostasis in plants, yet they are not studied in cotton. Here, we identify and analyze 65 FRO homologs (21 GhFRO, 21 GbFRO, 11 GaFRO, 12 GrFRO) across four Gossypium species (G. hirsutum, G. barbadense, G. arboreum, G. raimondii). FRO exhibit conserved ferric reductase activity and conserved domain structures; Ferric_reduct (PF01794), FAD_binding_8 (PF08022), and NAD_binding_6 (PF08030) across species. Physicochemical properties and subcellular localization analysis provided insights into FRO proteins' functional characteristics, mainly localized to the plasma membrane. Phylogenetic analysis delineates 11 groups, indicating both conserved and divergent evolutionary patterns. Gene structure analysis unveils varying exon-intron compositions. Chromosomal localization shows distribution across A and D genomes, suggesting evolutionary dynamics. Synteny analysis reveals paralogous and orthologous gene pairs subjected to purifying selection. The cis-regulatory elements analysis implicates diverse regulatory mechanisms. Expression profiling highlights dynamic regulation across developmental stages, abiotic and biotic stress conditions. GhFRO interacts with Ca++-dependent protein kinases-10/28-like (CDPKs10/28-like) and metal transporter Natural resistance-associated macrophage protein 6 (Nramp6) to regulate metal ion transport and iron homeostasis. The three-dimensional protein structure prediction suggests potential ligand-binding sites in FRO proteins. Moreover, qRT-PCR analysis of selected eight GhFROs in leaves treated with stress elicitors, MeJA, SA, NaCl, and PEG for 1h, 2h, 4h, and 6h revealed significant downregulation. Overall, this comprehensive study provides insights into FRO gene diversity, evolution, structure, regulation, and function in cotton, with implications for understanding plant iron homeostasis and stress responses.

Physiological and differential protein expression analyses of the calcium stress response in the Drynaria roosii rhizome

High concentration Ca2+ in karst soil is harmful to agriculture. Some dominant plants can adapt well to karst soil, but how Ca2+ affect plant is unknown. Drynaria roosii is a Ca2+-tolerant fern and its dry rhizome is a common Chinese medicine of Miao nationality in Guizhou, China. This study analyzed the physiological and proteomic characteristics of the rhizome of D. roosii under calcium stress. Physiological results indicated that calcium stress may lead to osmotic stress. Proteomic results showed that 147 differentially expressed proteins (96 increased, 51decreased) were identified under calcium stress, and these proteins mainly involved in signal transduction, protein translation, material transport, antioxidant defense and secondary metabolism. This study will lay a foundation for studying the calcium adaptation mechanism of D. roosii at the molecular level.

RsRbohD1 Plays a Significant Role in ROS Production during Radish Pithiness Development

Pithiness is one of the physiological diseases of radishes, which is accompanied by the accumulation of reactive oxygen species (ROS) during the sponging of parenchyma tissue in the fleshy roots. A respiratory burst oxidase homolog (Rboh, also known as NADPH oxidase) is a key enzyme that catalyzes the production of ROS in plants. To understand the role of Rboh genes in radish pithiness, herein, 10 RsRboh gene families were identified in the genome of Raphanus sativus using Blastp and Hmmer searching methods and were subjected to basic functional analyses such as phylogenetic tree construction, chromosomal localization, conserved structural domain analysis, and promoter element prediction. The expression profiles of RsRbohs in five stages (Pithiness grade = 0, 1, 2, 3, 4, respectively) of radish pithiness were analyzed. The results showed that 10 RsRbohs expressed different levels during the development of radish pithiness. Except for RsRbohB and RsRbohE, the expression of other members increased and reached the peak at the P2 (Pithiness grade = 2) stage, among which RsRbohD1 showed the highest transcripts. Then, the expression of 40 genes related to RsRbohD1 and pithiness were analyzed. These results can provide a theoretical basis for improving pithiness tolerance in radishes.

Investigation of two-pore K+ (TPK) channels in Triticum aestivum L. suggests their role in stress response

Two-pore K+ (TPK) channels are voltage-independent and involved in stress response in plants. Herein, we identified 12 TaTPK genes located on nine chromosomes in the Triticum aestivum genome. The majority of TaTPK genes comprised two exons. Each TaTPK channel comprised four transmembrane (TM) helices, N- and C-terminal ion-channel domains, two EF-hand domains and one 14-3-3 binding site. Additionally, highly conserved 'GYGD' motif responsible for K+ ion specificity, was found in between the TMs in both the ion-channel domains. Nine TaTPK channels were predicted to be localised at the plasma membrane, while three were vacuolar. The protein-protein and protein-chemical interactions indicated the coordinated functioning of the TaTPK channels with the other K+ transporters and their possible interaction with the Ca2+-signaling pathway. Expression studies suggested their importance in both vegetative and reproductive tissues development. Significantly modulated expression of various TaTPK genes during heat, drought, combined heat and drought and salt stresses, and after fungal infestation, depicted their function in stress responses. The miRNAs and transcription factors interaction analyses suggested their role in the hormone, light, growth and development-related, and stress-responsive signaling cascades. The current study suggested vital functions of various TaTPK genes, especially in stress response, and would provide an opportunity for their detailed characterization in future studies.

Overexpression of a Ramie (Boehmaeria nivea L. Gaud) Group I WRKY Gene, BnWRKY49, Increases Drought Resistance in Arabidopsis thaliana

Plants face multiple stresses in their natural habitats. WRKY transcription factors (TFs) play an important regulatory role in plant stress signaling, regulating the expression of multiple stress-related genes to improve plant stress resistance. In this study, we analyzed the expression profiles of 25 BnWRKY genes in three stages of ramie growth (the seedling stage, the rapid-growth stage, and the fiber maturity stage) and response to abiotic stress through qRT-PCR. The results indicated that 25 BnWRKY genes play a role in different growth stages of ramie and were induced by salt and drought stress in the root and leaf. We selected BnWRKY49 as a candidate gene for overexpression in Arabidopsis. BnWRKY49 was localized in the nucleus. Overexpression of BnWRKY49 affected root elongation under drought and salt stress at the Arabidopsis seedling stage and exhibited increased tolerance to drought stress. Further research found that BnWRKY49-overexpressing lines showed decreased stomatal size and increased cuticular wax deposition under drought compared with wild type (WT). Antioxidant enzyme activities of SOD, POD, and CAT were higher in the BnWRKY49-overexpressing lines than the WT. These findings suggested that the BnWRKY49 gene played an important role in drought stress tolerance in Arabidopsis and laid the foundation for further research on the functional analysis of the BnWRKYs in ramie.