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.

Arabidopsis contains 317 genes for defensin-like (DEFL) peptides. DEFLs have been grouped into different families based mainly on cysteine motifs. The DEFL0770 group contains seven genes, of which four are strongly expressed in roots. We found that the expression of these genes is downregulated in syncytia induced by the beet cyst nematode Heterodera schachtii as revealed by RNAseq analysis. We have studied one gene of this group, At3g59930, in detail. A promoter::GUS line revealed that the gene is only expressed in roots but not in other plant organs. Infection of the GUS line with larvae of H. schachtii showed a strong downregulation of GUS expression in infection sites as early as 1 dpi, confirming the RNAseq data. The At3g59930 peptide had only weak antimicrobial activity against Botrytis cinerea. Overexpression lines had no enhanced resistance against this fungus but were more resistant to H. schachtii infection. Our data indicate that At3g59930 is involved in resistance to nematodes which is probably not due to direct nematicidal activity.

In the dry regions of the Arabian Peninsula, such as Saudi Arabia, rangeland degradation and the decline of pasture species have significantly reduced phytomass production. The scarcity of grazing pastures has led to an expansion of alfalfa-irrigated fields, exacerbating the risk of water shortages. This study is the first to systematically evaluate the adaptability and production potential of Cenchrus ciliaris accessions in the arid environment of Saudi Arabia. The objective of this study is to evaluate the potential of buffelgrass (C. ciliaris) as an alternative to alfalfa in irrigated crop systems for livestock production and to assess its suitability for reintroduction into degraded rangelands to enhance forage production. For this purpose, accessions of C. ciliaris were collected from five different sites in northern Saudi Arabia (Aja, Jameen, Zaitoun, Gaed, and Industrial zone) to select the most vigorous ecotypes to be introduced in the degraded lands and/or to be used as irrigated forage crop. This study shows that under full irrigation (2500-3000 mm year⁻¹), alfalfa can produce 11.9 t ha⁻¹ to 22.6 t ha⁻¹ with a five-year average of 17 t ha⁻¹. However, C. ciliaris can produce 9.3–18.4 t ha⁻¹ with less water consumption than alfalfa (water supply is estimated at 400–500 mm year⁻¹). The average was about 14.1 t ha⁻¹. Our comparative study of these accessions showed that the Aja accession seemed to be the most salt tolerant, whereas the Jameen accession was the most well-developed, productive (18.4 t ha⁻¹), and overgrazing resistant accession (940.3 g plant⁻¹ after 3 cuts). Therefore, the Jameen accession is recommended for rangeland rehabilitation. In terms of chemical composition, C. ciliaris was less protein rich than alfalfa, but this can be compensated for by its high digestibility, estimated by neutral detergent fiber (NDF of 69.6%). This study identifies the Gaed and Jameen accessions as the most productive and grazing resistant, exhibiting drought and salt tolerance, making them suitable for use in irrigated systems to produce high green- and dry-matter yields or for reintroduction to rehabilitate degraded rangelands for rehabilitation purposes.

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.

Non-specific lipid transfer proteins (nsLTPs) are small cysteine-rich proteins belonging to the cysteine-rich peptide (CRP) antimicrobial peptide superfamily, widely distributed across land plants and involved in key physiological processes including fertilization, cell wall organization, wax deposition, and responses to biotic and abiotic stresses. Recent genomic and evolutionary analyses have revealed an extensive diversification of nsLTPs across plant lineages, which has led to multiple classification systems based on molecular mass, cysteine spacing, intron structure, and GPI (glycosylphosphatidylinositol-anchored proteins)-anchor motifs. This diversity reflects their adaptive expansion during plant terrestrialization. This review proposes that nsLTPs act as central nodes connecting lipid metabolism, developmental signals, and stress response networks, functioning as integrative signaling hubs rather than simple lipid carriers. Building on this central thesis, we synthesize current knowledge on nsLTP structure, classification, and evolution, and examine their multifaceted roles in plant development and defense. We also highlight emerging biotechnological applications and identify key gaps that warrant further investigation.