Cereal cyst nematodes (CCNs) are among the most important nematode pests that limit production of small grain cereals like wheat and barley. These nematodes alone are estimated to reduce production of crops by 10% globally. This necessitates a huge enhancement of nematode resistance in cereal crops against CCNs. Nematode resistance in wheat and barley in combination with higher grain yields has been a preferential research area for cereal nematologists. This usually involved the targeted genetic exploitations through natural means of classical selection breeding of resistant genotypes and finding quantitative trait luci (QTLs) associated with resistance genes. These improvements were based on available genetic diversity among the crop plants. Recently, genome-wide association studies have widely been exploited to associate nematode resistance or susceptibility with particular regions of the genome. Use of biotechnological tools through the application of various transgenic strategies for enhancement of nematode resistance in various crop plants including wheat and barley had also been an important area of research. These modern approaches primarily include the use of gene silencing, exploitation of nematode effector genes, proteinase inhibitors, chemodisruptive peptides and a combination of one or more of these approaches. Furthermore, the perspective genome editing technologies including CRISPR-Cas9 could also be helpful for improving CCN resistance in wheat and barley. The information provided in this review will be helpful to enhance resistance against CCNs and will attract the attention of the scientific community towards this neglected area.

Reactive oxygen species are a byproduct of aerobic metabolic processes but are also produced by plants in defense against pathogens. In addition, they can function as signaling molecules that control various aspects of plant life, ranging from developmental processes to responses to abiotic and biotic stimuli. In plants, reactive oxygen species can be produced by respiratory burst oxidase homologues. Arabidopsis contains 10 genes for respiratory burst oxidase homologues that are involved in different aspects of plant life. Plant pathogenic cyst nematodes such as Heterodera schachtii induce a syncytium in the roots of host plants that becomes a feeding site which supplies nutrients throughout the life of the nematode. In line with this function, the transcriptome of the syncytium shows drastic changes. One of the genes that is most strongly downregulated in syncytia codes for respiratory burst oxidase homologue B. This gene is root-specific and we confirm here the downregulation in nematode feeding sites with a promoter::GUS (β-glucuronidase) line. Overexpression of this gene resulted in enhanced resistance against nematodes but also against leaf-infecting pathogens. Thus, respiratory burst oxidase homologue B has a role in resistance. The function of this gene is in contrast to respiratory burst oxidase homologues D and F, which have been found to be needed for full susceptibility of Arabidopsis to H. schachtii. However, our bioinformatic analysis did not find differences between these proteins that could account for the opposed function in the interaction with nematodes.

Plants express various antimicrobial peptides including thionins to protect themselves against pathogens. It was recently found that, in addition to four thionin genes, Arabidopsis contains 67 thionin-like (ThiL) genes including six pseudogenes. It is known that thionins have antimicrobial activity and are part of the plant defense system, however, nothing is known about ThiL genes. In this study, we present a bioinformatic analysis of the (ThiL) gene family in Arabidopsis. We identified 15 different motifs which positioned the ThiL peptides in four groups. A comparison of amino acid sequences showed that the ThiL peptides are actually more similar to the acidic domain of thionin proproteins than to the thionin domain. We selected 10 ThiL genes to study the expression and possible function in the Arabidopsis plant. RT-PCR and promoter:GUS fusions showed that most genes were expressed at a very low level but in several organs and at different developmental stages. Some genes were also expressed in syncytia induced by the beet cyst nematode Heterodera schachti in roots while others were downregulated in syncytia. Some overexpression lines supported lower number of nematodes that developed on the roots after inoculation. Two of the genes resulted in a strong hypersensitive response when infiltrated into leaves of Nicotiana benthamiana. These results indicate that ThiL genes might be involved in the response to biotic stress. ThiL genes have been expanded in the Brassicales and specifically the Brassicaceae. The most extreme example is the CRP2460 subfamily that contains 28 very closely related genes from Arabidopsis which are mostly the result of tandem duplications.

Plant-parasitic nematodes, especially root-knot nematodes (RKNs), pose significant threats to global agriculture, affecting both the quantity and quality of crop yields. Central to the parasitism strategy of RKNs is the deployment of effector proteins, such as the 16D10 peptide, which interact with host plant resistance mechanisms. This study focuses on the computational analysis and molecular docking of 16D10 effector peptides derived from major RKN species (M. incognita, M. arenaria, M. hapla, M. javanica, and M. chitwoodi) to explore their interaction with the Mi resistance protein in tomatoes. Initial bioinformatics assessments included sequence retrieval, multiple sequence alignment, and phylogenetic analysis, utilizing tools such as CLUSTALW and the MEME Suite. Notably, our phylogenetic analysis revealed a close evolutionary relationship between M. incognita and M. chitwoodi, contrasting with other RKN species based on both DNA and protein data. Subsequent, in silico 3D modeling and docking studies, conducted using Chem-Sketch and MOE software, provided insights into the structural basis of the interaction between 16D10 peptides and the Mi protein. Our findings indicate that these interactions could play a crucial role in the modulation of plant defense mechanisms, potentially leading to effector-triggered susceptibility (ETS). This study not only enhances our understanding of nematode-host interactions but also aids in the development of novel strategies for managing RKN infections in economically important crops.

Reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, play a pivotal role in the early defense mechanisms of plants against biotic and abiotic stresses. Among the key contributors to ROS production are respiratory burst oxidase homologs (Rbohs), plant-specific NADPH oxidases that regulate stress responses, signaling, development, and programmed cell death. While Rboh gene families have been extensively studied in model plants like Arabidopsis thaliana, their characterization in other dicot species remains limited. Here, we conducted a genome-wide analysis of Rboh genes in four agriculturally important dicot species: Brassica oleracea, Daucus carota, Helianthus annuus, and Capsicum annuum. Using Arabidopsis Rboh sequences as references, we identified 38 Rboh genes across these species, which were compared with the 10 known Arabidopsis Rboh genes. Chromosomal mapping, gene structure, conserved domain, and motif analyses revealed that Rboh genes are evolutionarily conserved, with gene numbers aligning closely to those in previously studied plants. Phylogenetic analysis grouped these genes into two major clades and six subgroups, reflecting shared evolutionary lineages and potential functional similarities. Variations in exon-intron structures and unique domain duplications or deletions indicated possible functional divergence among specific genes. Chromosomal mapping showed uneven distribution of Rboh genes within each genome, consistent with patterns observed in other plant species. This study enhances the current understanding of the Rboh gene family in dicots, providing a foundation for future research on their functional roles and potential applications in improving plant resilience through genetic engineering or breeding strategies.