Plant Resistance Research Articles

Anti-mildew and fresh-keeping effect of Lactiplantibacillus paraplantarum P3 cell-free supernatant on fresh in-shell peanuts during storage process

Lactiplantibacillus paraplantarum P3 (L. paraplantarum P3) cell-free supernatant (CFS) with good antifungal effect was sprayed on fresh in-shell peanuts stored at 5 °C and 30 °C to explore its effect on the microorganisms and quality of fresh in-shell peanuts during storage process. Results showed that L. paraplantarum P3 CFS effectively maintained good quality of fresh in-shell peanuts by not only reducing fungi amount and the mildew rate, but also improving the morphology, color and flavor. Besides, L. paraplantarum P3 CFS activated plant mitogen-activated protein kinase signaling pathway and plant hormone signaling pathway to produce more ethylene, gibberellin regulatory proteins and other substances to enhance plant resistance to pathogenic microorganisms. L. paraplantarum P3 CFS could also induce the biosynthesis of glycerophospholipid and arginine to increase the stress resistance of fresh peanuts. This study provides research data for the application of L. paraplantarum P3 CFS in the preservation and antimildew of fresh in-shell peanuts.

PHYLOGENETIC CONNECTIONS AND COMPARISONS OF THE AMINO ACID SEQUENCES OF SEVERAL PEPTIDE INDUCERS OF MICROBIAL ORIGIN- A FOUNDATION STUDY FOR DEVELOPMENT OF NOVEL BIOPESTICIDES

Peptides of microbial origin stand out as one of theprominent tools to elicit plant immunity. These peptides comprise one of thekey strategies of integrated pest management and are considered as candidatesto develop novel biopesticides. Manyresearch investigations have proved their potential in fending off plantpathogens and were described as sustainable plant protection strategies. Thepresent study was attempted to discover phylogenetic relationships and compareamino acid sequence alignments of various peptide elicitors of microbialorigin. Phylogenetic analysis of 33 microbial peptide elicitors resulted in twoclusters, one cluster contained 19 flagellin sequences, which is furtherdivided into one major (15 peptide sequences) and one (4 peptide sequences)minor subclusters. Further amino acid sequence alignments were carried outbased on the evolutionary relationships among the peptides. The amino acidsequence alignment of flagellin sequences using Clustal W did not present conservativeamino acid sequences except Serine (S), Alanine (A) and Aspartic acid (D).These conserved amino acids (SAxD) that are positioned in the protruding loopmay play a vital role in recognition by plant surface receptors. Alignment ofamino acid sequences of cold shock protein, xylanase, elongation factor andharpin from various sources did not present conservative amino acid sequencesexcept glycine. These investigations lay a theoretical foundation for exploringmany more microbial peptides for inducing plant resistance.

Genetic mapping of loci affecting seedling and adult-plant resistance to powdery mildew derived from two CIMMYT wheat lines.

PM3 and PM8 alleles carried by two CIMMYT wheat lines confer powdery mildew resistance in seedlings and/or adult plants. A stage-specific epistatic interaction was observed between PM3 and PM8. Powdery mildew is an important foliar disease of wheat. Major genes for resistance, which have been widely used in wheat breeding programs, are typically effective against only limited numbers of virulence genes of the pathogen. The main aim of this study was to map resistance loci in wheat lines 7HRWSN58 and ZWW09-149 from the International Maize and Wheat Improvement Center (CIMMYT). Doubled haploid populations (Magenta/7HRWSN58 and Emu Rock/ZWW09-149) were developed and grown in controlled environment experiments and inoculated with a composite of Blumeria graminis f.sp. tritici isolates that had been collected at various locations in Western Australia. Plants were assessed for powdery mildew symptoms (percentage leaf area diseased) on seedlings and adult plants. Populations were subjected to genotyping-by-sequencing and assayed for known SNPs in the resistance gene PM3. Linkage maps were constructed, and markers were anchored to the wheat reference genome sequence. In both populations, there were asymptomatic lines that exhibited no symptoms. Among symptomatic lines, disease severity varied widely. In the Magenta/7HRWSN58 population, most of the observed variation was attributed to the PM3 region of chromosome 1A, with the allele from 7HRWSN58 conferring resistance in seedlings and adult plants. In the Emu Rock/ZWW09-149 population, two interacting quantitative trait loci were mapped: one at PM3 and the other on chromosome 1B. The Emu Rock/ZWW09-149 population was confirmed to segregate for a 1BL·1RS translocation that carries the PM8 powdery mildew resistance gene from rye. Consistent with previous reports that PM8-derived resistance can be suppressed by PM3 alleles, the observed interaction between the quantitative trait loci on chromosomes 1A and 1B indicated that the PM3 allele carried by ZWW09-149 suppresses PM8-derived resistance from ZWW09-149, but only at the seedling stage. In adult plants, the PM8 region conferred resistance regardless of the PM3 genotype. The resistance sources and molecular markers that were investigated here could be useful in wheat breeding.

Arabidopsis Transcriptomics Reveals the Role of Lipoxygenase2 (AtLOX2) in Wound-Induced Responses

In wounded Arabidopsis thaliana leaves, four 13S-lipoxygenases (AtLOX2, AtLOX3, AtLOX4, AtLOX6) act in a hierarchical manner to contribute to the jasmonate burst. This leads to defense responses with LOX2 playing an important role in plant resistance against caterpillar herb-ivory. In this study, we sought to characterize the impact of AtLOX2 on wound-induced phytohormonal and transcriptional responses to foliar mechanical damage using wildtype (WT) and lox2 mutant plants. Compared with WT, the lox2 mutant had higher constitutive levels of the phytohormone salicylic acid (SA) and enhanced expression of SA-responsive genes. This suggests that AtLOX2 may be involved in the biosynthesis of jasmonates that are involved in the antagonism of SA biosynthesis. As expected, the jasmonate burst in response to wounding was dampened in lox2 plants. Generally, 1 h after wounding, genes linked to jasmonate biosynthesis, jasmonate signaling attenuation and abscisic acid-responsive genes, which are primarily involved in wound sealing and healing, were differentially regulated between WT and lox2 mutants. Twelve h after wounding, WT plants showed stronger expression of genes associated with plant protection against insect herbivory. This study highlights the dynamic nature of jasmonate-responsive gene expression and the contribution of AtLOX2 to this pathway and plant resistance against insects.

Conifers concentrate large numbers of NLR immune receptor genes on one chromosome.

Nucleotide-binding domain and Leucine-rich Repeat (NLR) immune receptor genes form a major line of defence in plants, acting in both pathogen recognition and resistance machinery activation. NLRs are reported to form large gene clusters in limber pine (Pinus flexilis) but it is unknown how widespread this genomic architecture may be among the extant species of conifers (Pinophyta). We used comparative genomic analyses to assess patterns in the abundance, diversity and genomic distribution of NLR genes. Chromosome-level whole genome assemblies and high-density linkage maps in the Pinaceae, Cupressaceae, Taxaceae and other gymnosperms were scanned for NLR genes using existing and customised pipelines. Discovered genes were mapped across chromosomes and linkage groups and analysed phylogenetically for evolutionary history. Conifer genomes are characterised by dense clusters of NLR genes, highly localised on one chromosome. These clusters are rich in TNL-encoding genes, which seem to have formed through multiple tandem duplication events. In contrast to angiosperms and non-coniferous gymnosperms, genomic clustering of NLR genes is ubiquitous in conifers. NLR-dense genomic regions are likely to influence a large part of the plant's resistance, informing our understanding of adaptation to biotic stress and the development of genetic resources through breeding.

Transcriptome and metabolome analyses reveal the regulatory role of MdPYL9 in drought resistance in apple

BackgroundThe mechanisms by which the apple MdPYL9 gene mediates the response to drought stress remain unclear. Here, transcriptome and metabolome analyses of apple plants under drought were used to investigate the mechanisms by which MdPYL9 regulates the response to drought stress in apple. MdPYL9-overexpressed transgenic and non-transgenic apple histoculture seedlings were rooted, transplanted, and subjected to drought treatments to clarify the mechanisms underlying the responses of apples to drought stress through phenotypic observations, physiological and biochemical index measurements, and transcriptomic and metabolomic analyses.ResultsUnder drought stress treatment, transgenic plants were less affected by drought stress than non-transgenic plants. Decreases in the net photosynthetic rate, stomatal conductance, and transpiration rate of transgenic apple plants were less pronounced in transgenic plants than in non-transgenic plants, and increases in the intercellular CO2 concentration were less pronounced in transgenic plants than in non-transgenic plants. The relative electrical conductivity and content of malondialdehyde, superoxide anion, and hydrogen peroxide were significantly lower in transgenic plants than in non-transgenic plants, and the chlorophyll content and activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) were significantly higher in transgenic plants than in non-transgenic plants. The number of differentially expressed genes (DEGs) involved in the response to drought stress was lower in transgenic plants than in non-transgenic plants, and the most significant and highly annotated DEGs in the transgenic plants were involved in the flavonoid biosynthesis pathway, and the most significant and highly annotated DEGs in control plants were involved in the phytohormone signal transduction pathway. The number of differentially accumulated metabolites involved in the response to drought stress was lower in transgenic plants than in non-transgenic plants, and up-regulated metabolites were significantly enriched in apigenin-7-O-glucoside in transgenic plants and in abscisic acid in non-transgenic plants. In the flavonoid biosynthetic pathway, the expression of genes encoding chalcone synthase (CHS) and chalcone isomerase (CHI) was more significantly down-regulated in non-transgenic plants than in transgenic plants, and the expression of the gene encoding 4-coumarate-CoA ligase (4CL) was more significantly up-regulated in transgenic plants than in non-transgenic plants, which resulted in the significant up-regulation of apigenin-7-O-glucoside in transgenic plants.ConclusionsThe above results indicated that the over-expression of MdPYL9 increased the drought resistance of plants under drought stress by attenuating the down-regulation of the expression of genes encoding CHS and CHI and enhancing the up-regulated expression of the gene encoding 4CL, which enhanced the content of apigenin-7-O-glucoside.

Effects of water and exogenous glucose on apple seedling growth and soil enzyme activity in semiarid area.

Soil water and organic carbon (C) are key factors affecting the growth and development of apple seedlings. The objective of the study was to investigate the effects of different soil moisture and glucose supplies on apple seedling growth and soil enzyme activities. We hypothesized that the growth of apple seedlings was affected by soil water and C content through their effects on root structure, plant physiological properties and soil enzymatic activities. A pot experiment consisting of nine treatments was set up, including three water treatments with soil moisture contents at 75-85% (normal irrigation, CK), 65-75% (light water stress, LS), and 55-65% (mild water stress, MS) of the soil field capacity, in combination with three glucose treatments with carbon/nitrogen (C/N) ratio of 7.5 (C1, no adding glucose), 10 (C2) and 15 (C3), respectively. Results showed that the LSC2 treatment significantly increased plant height by 7%, stem diameter by 5% and leaf area by 17%, as compared with LSC1. Also, LSC2 significantly increased root dry weight, root vitality and soil enzyme activities. Moreover, results of leaf photosynthetic, malondialdehyde (MDA), peroxidase (POD), superoxide dismutase (SOD) and proline contents also proved that adding glucose improved the drought resistance of plants. LSC2 treatment is more conducive to the growth of apple seedlings, and application of carbon has a good alleviation effect on plant water stress. The study demonstrated that addition of exogenous glucose alleviated light water deficiency, significantly affected root vitality, and promoted apple seedling growth. © 2024 Society of Chemical Industry.

Endophyte-mediated enhancement of salt resistance in Arachis hypogaea L. by regulation of osmotic stress and plant defense-related genes

IntroductionSoil salinization poses a significant environmental challenge affecting plant growth and agricultural sustainability. This study explores the potential of salt-tolerant endophytes to mitigate the adverse effects of soil salinization, emphasizing their impact on the development and resistance of Arachis hypogaea L. (peanuts).MethodsThe diversity of culturable plant endophytic bacteria associated with Miscanthus lutarioriparius was investigated. The study focused on the effects of Bacillus tequilensis, Staphylococcus epidermidis, and Bacillus siamensis on the development and germination of A. hypogaea seeds in pots subjected to high NaCl concentrations (200 mM L−1).ResultsUnder elevated NaCl concentrations, the inoculation of endophytes significantly (p < 0.05) enhanced seedling germination and increased the activities of enzymes such as Superoxide dismutase, catalase, and polyphenol oxidase, while reducing malondialdehyde and peroxidase levels. Additionally, endophyte inoculation resulted in increased root surface area, plant height, biomass contents, and leaf surface area of peanuts under NaCl stress. Transcriptome data revealed an augmented defense and resistance response induced by the applied endophyte (B. tequilensis, S. epidermidis, and B. siamensis) strain, including upregulation of abiotic stress related mechanisms such as fat metabolism, hormones, and glycosyl inositol phosphorylceramide (Na+ receptor). Na+ receptor under salt stress gate Ca2+ influx channels in plants. Notably, the synthesis of secondary metabolites, especially genes related to terpene and phenylpropanoid pathways, was highly regulated.ConclusionThe inoculated endophytes played a possible role in enhancing salt tolerance in peanuts. Future investigations should explore protein–protein interactions between plants and endophytes to unravel the mechanisms underlying endophyte-mediated salt resistance in plants.

Glutamate Receptor-like (GLR) Family in Brassica napus: Genome-Wide Identification and Functional Analysis in Resistance to Sclerotinia sclerotiorum

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.

Evaluation of a low-cost staining method for improved visualization of sweet potato whitefly (Bemisia tabaci) eggs on multiple crop plant species

BackgroundThe sweet potato whitefly (Bemisia tabaci) is a globally important insect pest that damages crops through direct feeding and by transmitting viruses. Current B. tabaci management revolves around the use of insecticides, which are economically and environmentally costly. Host plant resistance is a sustainable option to reduce the impact of whiteflies, but progress in deploying resistance in crops has been slow. A major obstacle is the high cost and low throughput of screening plants for B. tabaci resistance. Oviposition rate is a popular metric for host plant resistance to B. tabaci because it does not require tracking insect development through the entire life cycle, but accurate quantification is still limited by difficulties in observing B. tabaci eggs, which are microscopic and translucent. The goal of our study was to improve quantification of B. tabaci eggs on several important crop species: cassava, cowpea, melon, sweet potato and tomato.ResultsWe tested a selective staining process originally developed for leafhopper eggs: submerging the leaves in McBryde’s stain (acetic acid, ethanol, 0.2% aqueous acid Fuchsin, water; 20:19:2:1) for three days, followed by clearing under heat and pressure for 15 min in clearing solution (LGW; lactic acid, glycerol, water; 17:20:23). With a less experienced individual counting the eggs, B. tabaci egg counts increased after staining across all five crops. With a more experienced counter, egg counts increased after staining on melons, tomatoes, and cowpeas. For all five crops, there was significantly greater agreement on egg counts across the two counting individuals after the staining process. The staining method worked particularly well on melon, where egg counts universally increased after staining for both counting individuals.ConclusionsSelective staining aids visualization of B. tabaci eggs across multiple crop plants, particularly species where leaf morphological features obscure eggs, such as melons and tomatoes. This method is broadly applicable to research questions requiring accurate quantification of B. tabaci eggs, including phenotyping for B. tabaci resistance.

A soybean bZIP transcription factor is involved in submergence resistance

Although the functions of basic leucine zipper (bZIP) family transcription factors in the regulation of various abiotic stresses are beginning to be unveiled, the precise roles of bZIP proteins in plants coping with submergence stress remain unclear. Here we identified a bZIP gene GmbZIP71-4 from soybean, which localized in the nucleus. The GmbZIP71-4 over-expressed tabocco line showed reduced submergence resistance due to the decreased abscisic acid (ABA) content. GO and KEGG pathway analysis based on chromatin immunoprecipitation assay sequencing (ChIP-seq) indicated that the differences expressed genes between submergence treatment and control groups were specially enriched in plant hormone signal transduction items, especially those in response to ABA. Electrophoretic mobility shift assays (EMSA) demonstrated that GmbZIP71-4 bound to the promoter of GmABF2 gene, which is consistent with the ChIP-qPCR results. GmbZIP71-4 function as a negative regulator of soybean in responding to submergence stress through manipulating ABA signaling pathway. This findings will set a solid foundation for the understanding of submergence resistance in plants.

The effects of Lr34 and Lr67 on Fusarium head blight resistance and deoxynivalenol accumulation in wheat

AbstractThe resistance gene Lr34 conditions durable disease resistance to many biotrophic wheat pathogens and has been incorporated into many wheat cultivars throughout the world. Lr67 is a similar adult plant resistance gene that also conditions resistance to multiple wheat diseases. Both genes significantly reduce disease severity and work in an additive manner with other rust resistance genes. To determine the effect of Lr34 and Lr67 on Fusarium head blight (FHB), two doubled haploid populations, segregating for each of these genes, were developed in the Thatcher wheat background by crossing near‐isogenic lines. Progeny from these populations were tested in five Fusarium graminearum‐inoculated disease nurseries and assessed for FHB symptoms, using a visual rating index (VRI), and deoxynivalenol (DON) accumulation. Both Lr34 and Lr67 significantly reduced visual symptoms of FHB and DON overall, though those effects were not significant in all environments. The overall reduction in the group of progeny with the resistant allele compared to the group with the susceptible allele for VRI was 9.4% for Lr34 and 6.8% for Lr67, while for DON it was 16.4% for Lr34 and 14.9% for Lr67. These genes represent important tools for improving resistance to FHB and many other diseases in wheat.

Defense Pathways of Wheat Plants Inoculated with Zymoseptoria tritici under NaCl Stress Conditions: An Overview

Due to being sessile, plants develop a broad range of defense pathways when they face abiotic or biotic stress factors. Although plants are subjected to more than one type of stress at a time in nature, the combined effects of either multiple stresses of one kind (abiotic or biotic) or more kinds (abiotic and biotic) have now been realized in agricultural lands due to increases in global warming and environmental pollution, along with population increases. Soil-borne pathogens, or pathogens infecting aerial parts, can have devastating effects on plants when combined with other stressors. Obtaining yields or crops from sensitive or moderately resistant plants could be impossible, and it could be very difficult from resistant plants. The mechanisms of combined stress in many plants have previously been studied and elucidated. Recent studies proposed new defense pathways and mechanisms through signaling cascades. In light of these mechanisms, it is now time to develop appropriate strategies for crop protection under multiple stress conditions. This may involve using disease-resistant or stress-tolerant plant varieties, implementing proper irrigation and drainage practices, and improving soil quality. However, generation of both stress-tolerant and disease-resistant crop plants is of crucial importance. The establishment of a database and understanding of the defense mechanisms under combined stress conditions would be meaningful for the development of resistant and tolerant plants. It is clear that leaf pathogens show great tolerance to salinity stress and result in pathogenicity in crop plants. We noticed that regulation of the stomata through biochemical applications and some effort with the upregulation of the minor gene expressions indirectly involved with the defense mechanisms could be a great way to increase the defense metabolites without interfering with quality parameters. In this review, we selected wheat as a model plant and Zymoseptoria tritici as a model leaf pathogen to evaluate the defense mechanisms under saline conditions through physiological, biochemical, and molecular pathways and suggested various ways to generate tolerant and resistant cereal plants.

Intermittent water stress favors microbial traits that better help wheat under drought

Abstract Microorganisms can improve plant resistance to drought through various mechanisms such as the production of plant hormones, osmolytes, antioxidants, and exopolysaccharides. It is, however, unclear how previous exposure to water stress affects the functional capacity of the soil microbial community to help plants resist drought. We compared two soils that had either a continuous or intermittent water stress history for almost forty years. We grew wheat in these soils and subjected it to a water stress, after which we collected the rhizosphere soil and shotgun sequenced its metagenome. Wheat growing in the soil with an intermittent water stress history maintained a higher biomass when subjected to water stress. Genes related to indole-acetic acid and osmolyte production were more abundant in the metagenome of the soil with an intermittent water stress history as compared to the soil with a continuous water stress history. We suggest that an intermittent water stress history selects traits beneficial for life under water stress.

Practical applications of spent mushroom compost in cultivation and disease control of selected vegetables species

AbstractMushroom cultivation is an important branch of the agricultural industry, and global mushrooms production has increased more than sixfold in the last decade. This industry uses large amounts of agricultural, forestry, livestock, and industrial wastes and their by-products. However, it also generates millions of tons of spent mushroom compost (SMC) (approximately 100 million tons per year) which has emerged as a significant issue that hinders the growth of the mushroom business and impacts the environment. Many crop diseases, which cause significant economic losses, are introduced by soil-borne plant pathogens. Spreading spent mushroom compost (SMC) to agricultural soils is a natural way to control plant diseases. Using organic waste material instead of chemicals, which is the most widely used method in agriculture today, is also a more environmentally responsible option. The generated SMC can potentially be used as a soil conditioner, an organic fertilizer, and suitable medium for growing various vegetable crops. The application of SMC has been found to be beneficial in the control of crop diseases by inducing microbiostasis, direct toxicity, or by inducing systemic resistance of the host plant. In the current review, the practical application of SMC in the cultivation of tomato, pepper, lettuce, cucumber, and eggplant was addressed. The application of SMC as a soil amendment showed a significant improvement in soil properties, including soil NPK, organic matter content, and soil beneficial microorganisms. Our review indicated that SMC could be used as a low-cost, alternative growing medium in vegetable production or as a soil amendment to add nutrients and restore soil fertility in agricultural lands. The SMC may be able to replace peat, a non-renewable natural resource, and thereby mitigating the adverse effects of excessive peat extraction in wetlands, bogs, marshes, and peatlands. This review uses unique data on the effective use of SMC in agricultural disease management, reducing the need for chemical pesticides that have adverse effects on both the environment and human health. It also provides a safe method for reusing, recycling, and integrating SMC into a circular economy that reduces its negative environmental effects and carbon footprint impacts. This work also offers a novel application of SMC as a low-cost substitute for peat or other growing media that pose environmental risks. Graphical abstract

Assessing the relationship between the biochemical and the morphological factors (leaf surface area and leaf surface texture) of industrial and roadside plants.

The study of biochemical parameters provides an idea of the resistance of plants against air pollutants. Biochemical and Physiological parameters are studied with the help of Air pollution tolerance index (APTI). Fifteen plant species were evaluated to assess biochemical and APTI from two polluted sites (Phagwara Industrial area and Phagwara Bus stand area). The values of APTI were found to be highest for Mangifera indica (19.6), Ficus religiosa (19.3), and Ficus benghalensis (15.8) in the industrial area. On the roadside, Mangifera indica (16.8), Ficus benghalensis (16.5), and Ficus religiosa (16.4). Mangifera indica, Ficus religiosa, and Ficus benghalensis were found to be excellent performers in reducing pollution at both the sampling sites as per the APTI values. The order of tolerance was Mangifera indica > Ficus religiosa > Ficus benghalensis > Polyalthia longifolia > Mentha piperita in both the polluted sites. Morphological changes were observed in the plants, suggesting the possibility of pollution stress, which is probably responsible for the changes in biochemical parameters. As a result, the relationship between morphological and biochemical parameters of selected plant species growing in roadside and industrial areas was explored. The findings revealed that relative water content showed a significant positive and negative correlation with leaf surface texture and leaf surface area. On the other hand, ascorbic acid showed a significant positive correlation with them. In conclusion, it has been studied that morphological parameters including biochemical parameters can be proved to be important in investigating the ability of plants to cope with air pollution and in calculating tolerance index.

Recent Advances in Understanding and Controlling Fusarium Diseases of Alliums

Allium species are known for their culinary, medicinal, and ornamental purposes. Fusarium basal rot is one of the most damaging soilborne fungal diseases of Allium species and poses a significant threat to yield, quality, and storage life worldwide. Various species of Fusarium have been identified as causal agents for Fusarium basal rot, depending on the Allium species involved. Diverse disease management practices have been implemented to mitigate the impact of Fusarium basal rot. This review article provides a comprehensive overview of the recent progress in detecting different species of Fusarium involved in Fusarium basal rot and strategies to control them in affected Allium species involving chemical, biological, and cultural methods. It covers the latest advancements in host plant resistance research from traditional breeding to modern molecular techniques and studying secondary metabolites involved in defense mechanisms against Fusarium basal rot.

Enhancing Salt Stress Tolerance in Tomato (Solanum lycopersicum L.) through Silicon Application in Roots.

Soil salinization poses a significant threat to agricultural productivity, necessitating innovative agronomic strategies to mitigate its impact. This study focuses on improving salt stress resistance in tomato plants through the application of silicon (Si) in roots. A greenhouse experiment was carried out under normal conditions (control, and 1 and 4 mM Si) and under salinity stress (salt control, and 1 and 4 mM Si). Various parameters were analyzed in leaves and roots. Under normal conditions, tomato plants grown in non-saline conditions exhibited some toxicity when exposed to Na2SiO3. As for the experiments under salt stress conditions, Si mitigated oxidative damage, preserving root cell membrane integrity. The concentration of malondialdehyde was reduced by 69.5%, that of proline was reduced by 56.4% and there was a 57.6% decrease in catalase activity for tomato plants treated with 1 mM Si under salt stress. Furthermore, Fe uptake and distribution, under salt conditions, increased from 91 to 123 mg kg-1, the same concentration as that obtained for the normal control. In all cases, the lower dose produced better results under normal conditions than the 4 mM dose. In summary, this research provides a potential application of Si in non-fertigated crop systems through a radicular pathway.

Hydrogen Sulfide Increases Drought Tolerance by Modulating Carbon and Nitrogen Metabolism in Foxtail Millet Seedlings

Hydrogen sulfide (H2S), a novel gas signaling molecule, has been shown to enhance plant resistance to various abiotic stresses. Here, we investigated the effect of sodium hydrosulfide (NaHS, a H2S donor) on the growth, photosynthetic parameters, and enzyme activities related to carbon and nitrogen metabolism, as well as the levels of carbohydrates and nitrogen metabolites in foxtail millet seedlings subjected to drought stress conditions in pots. The findings revealed that drought stress led to a significant 41.2% decline in the total dry weight (DW) after 12 days of treatment, whereas plants treated with NaHS showed a lesser reduction of 18.7% in total DW. Under drought stress, exogenous NaHS was found to enhance carbon metabolism in foxtail millet seedlings by significantly enhancing photosynthetic capacity, starch, and sucrose content. Additionally, exogenous NaHS was observed to improve nitrogen metabolism by substantially increasing soluble protein content, nitrogen assimilate activity, and synthesis of nitrogen-containing compounds in foxtail millet seedlings. In summary, the exogenous application of NaHS stimulated seedling growth and enhanced drought resistance in foxtail millet by modulating carbon and nitrogen metabolism processes affected by drought stress.

Identification and mechanism characterization of Streptomyces griseoaurantiacus XQ-29 with biocontrol ability against pepper southern blight caused by Sclerotium rolfsii

Pepper southern blight, caused by Sclerotium rolfsii, is a devastating soil-borne disease resulting in significant loss to pepper, Capsicum annuum L. production.Here, we isolated an antagonistic bacterial strain XQ-29 with antifungal activity against S. rolfsii from rhizospheric soil of pepper. Combining the morphological and biochemical characteristics with the 16S rDNA sequencing, XQ-29 was identified as Streptomyces griseoaurantiacus. It exhibited an inhibition of 96.83% against S. rolfsii and displayed significant inhibitory effects on Botrytis cinerea, Phytophthora capsica and Rhizoctonia solani. Furthermore, XQ-29 significantly reduced the pepper southern blight by 100% and 70.42% during seedling and growth stages, respectively. The antifungal mechanism involved altering the mycelial morphology, disrupting cell wall and membrane integrity, accompanied by accumulation of reactive oxygen species and lipid peroxidation in S. rolfsii mycelia. Furthermore, XQ-29 promoted growth and stimulated resistance of pepper plants by increasing defense-related enzyme activities and upregulating defense-related genes. Correspondingly, XQ-29 harbors numerous functional biosynthesis gene clusters in its genome, including those for siderophores and melanin production. The metabolic constituents present in the ethyl acetate extracts, which exhibited an EC50 value of 85.48 ± 1.62 μg/mL, were identified using LC-MS. Overall, XQ-29 demonstrates significant potential as a biocontrol agent against southern blight disease.