The GhEB1C gene mediates resistance of cotton to Verticillium wilt.

MAIN CONCLUSION: The GhEB1C gene of the EB1 protein family functions as microtubule end-binding protein and may be involved in the regulation of microtubule-related pathways to enhance resistance to Verticillium wilt. The expression of GhEB1C is induced by SA, also contributing to Verticillium wilt resistance. Cotton, as a crucial cash and oil crop, faces a significant threat from Verticillium wilt, a soil-borne disease induced by Verticillium dahliae, severely impacting cotton growth and development. Investigating genes associated with resistance to Verticillium wilt is paramount. We identified and performed a phylogenetic analysis on members of the EB1 family associated with Verticillium wilt in this work. GhEB1C was discovered by transcriptome screening and was studied for its function in cotton defense against V. dahliae. The RT-qPCR analysis revealed significant expression of the GhEB1C gene in cotton leaves. Subsequent localization analysis using transient expression demonstrated cytoplasmic localization of GhEB1C. VIGS experiments indicated that silencing of the GhEB1C gene significantly increased susceptibility of cotton to V. dahliae. Comparative RNA-seq analysis showed that GhEB1C silenced plants exhibited altered microtubule-associated protein pathways and flavonogen-associated pathways, suggesting a role for GhEB1C in defense mechanisms. Overexpression of tobacco resulted in enhanced resistance to V. dahliae as compared to wild-type plants. Furthermore, our investigation into the relationship between the GhEB1C gene and plant disease resistance hormones salicylic axid (SA) and jasmonic acid (JA) revealed the involvement of GhEB1C in the regulation of the SA pathway. In conclusion, our findings demonstrate that GhEB1C plays a crucial role in conferring immunity to cotton against Verticillium wilt, providing valuable insights for further research on plant adaptability to pathogen invasion.

Autophagy plays an antiviral defence role against tomato spotted wilt orthotospovirus and is counteracted by viral effector NSs.

Autophagy, an intracellular degradation process, has emerged as a crucial innate immune response against various plant pathogens, including viruses. Tomato spotted wilt orthotospovirus (TSWV) is a highly destructive plant pathogen that infects over 1000 plant species and poses a significant threat to global food security. However, the role of autophagy in defence against the TSWV pathogen, and whether the virus counteracts this defence, remains unknown. In this study, we report that autophagy plays an important role in antiviral defence against TSWV infection; however, this autophagy-mediated defence is counteracted by the viral effector NSs. Transcriptome profiling revealed the up-regulation of autophagy-related genes (ATGs) upon TSWV infection. Blocking autophagy induction by chemical treatment or knockout/down of ATG5/ATG7 significantly enhanced TSWV accumulation. Notably, the TSWV nucleocapsid (N) protein, a major component of the viral replication unit, strongly induced autophagy. However, the TSWV nonstructural protein NSs was able to effectively suppress N-induced autophagy in a dose-dependent manner. Further investigation revealed that NSs inhibited ATG6-mediated autophagy induction. These findings provide new insights into the defence role of autophagy against TSWV, a representative segmented negative-strand RNA virus, as well as the tospoviral pathogen counterdefence mechanism.

The host and pathogen myo-inositol-1-phosphate synthases are required for Rhizoctonia solani AG1-IA infection in tomato.

The myo-inositol-1-phosphate synthase (MIPS) catalyses the biosynthesis of myo-inositol, an important sugar that regulates various physiological and biochemical processes in plants. Here, we provide evidence that host (SlMIPS1) and pathogen (Rs_MIPS) myo-inositol-1-phosphate synthase (MIPS) genes are required for successful infection of Rhizoctonia solani, a devastating necrotrophic fungal pathogen, in tomato. Silencing of either SlMIPS1 or Rs_MIPS prevented disease, whereas an exogenous spray of myo-inositol enhanced disease severity. SlMIPS1 was upregulated upon R. solani infection, and potentially promoted source-to-sink transition, induced SWEET gene expression, and facilitated sugar availability in the infected tissues. In addition, salicylic acid (SA)-jasmonic acid homeostasis was altered and SA-mediated defence was suppressed; therefore, disease was promoted. On the other hand, silencing of SlMIPS1 limited sugar availability and induced SA-mediated defence to prevent R. solani infection. Virus-induced gene silencing of NPR1, a key gene in SA signalling, rendered SlMIPS1-silenced tomato lines susceptible to infection. These analyses suggest that induction of SA-mediated defence imparts disease tolerance in SlMIPS1-silenced tomato lines. In addition, we present evidence that SlMIPS1 and SA negatively regulate each other to modulate the defence response. SA treatment reduced SlMIPS1 expression and myo-inositol content in tomato, whereas myo-inositol treatment prevented SA-mediated defence. We emphasize that downregulation of host/pathogen MIPS can be an important strategy for controlling diseases caused by R. solani in agriculturally important crops.

ATP-binding cassette transporter TaABCG2 contributes to Fusarium head blight resistance by mediating salicylic acid transport in wheat.

ATP-binding cassette (ABC) transporters hydrolyse ATP to transport various substrates. Previous studies have shown that ABC transporters are responsible for transporting plant hormones and heavy metals, thus contributing to plant immunity. Herein, we identified a wheat G-type ABC transporter, TaABCG2-5B, that responds to salicylic acid (SA) treatment and is induced by Fusarium graminearum, the primary pathogen causing Fusarium head blight (FHB). The loss-of-function mutation of TaABCG2-5B (ΔTaabcg2-5B) reduced SA accumulation and increased susceptibility to F. graminearum. Conversely, overexpression of TaABCG2-5B (OE-TaABCG2-5B) exerted the opposite effect. Quantification of intracellular SA in ΔTaabcg2-5B and OE-TaABCG2-5B protoplasts revealed that TaABCG2-5B acts as an importer, facilitating the transport of SA into the cytoplasm. This role was further confirmed by Cd2+ absorption experiments in wheat roots, indicating that TaABCG2-5B also participates in Cd2+ transport. Thus, TaABCG2-5B acts as an importer and is crucial for transporting multiple substrates. Notably, the homologous gene TaABCG2-5A also facilitated Cd2+ uptake in wheat roots but did not significantly influence SA accumulation or FHB resistance. Therefore, TaABCG2 could be a valuable target for enhancing wheat tolerance to Cd2+ and improving FHB resistance.

A receptor for dual ligands governs plant immunity and hormone response and is targeted by a nematode effector.

In this study, we show that the potato (Solanum tuberosum) pattern recognition receptor (PRR) NEMATODE-INDUCED LEUCINE-RICH REPEAT (LRR)-RLK1 (StNILR1) functions as a dual receptor, recognizing both nematode-associated molecular pattern ascaroside #18 (Ascr18) and plant hormone brassinosteroid (BR) to activate two different physiological outputs: pattern-triggered immunity (PTI) and BR response. Ascr18/BR-StNILR1 signaling requires the coreceptor potato BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1 (StBAK1) and perception of either ligand strengthens StNILR1 interaction with StBAK1 in plant cells. Significantly, the parasitically successful potato cyst nematode (Globodera pallida) utilizes the effector RHA1B, which is a functional ubiquitin ligase, to target StNILR1 for ubiquitination-mediated proteasome-dependent degradation, thereby countering Ascr18/BR-StNILR1-mediated PTI in potato and facilitating nematode parasitism. These findings broaden our understanding of PRR specificity and reveal a nematode parasitic mechanism that targets a PTI signaling pathway.

Nanomaterial inactivates environmental virus and enhances plant immunity for controlling tobacco mosaic virus disease.

Tobacco mosaic virus (TMV) is extremely pathogenic and resistant to stress There are great needs to develop methods to reduce the virus in the environment and induce plant immunity simultaneously. Here, we report a multifunctional nano-protectant to reduce the virus in the environment and induce plant immunity simultaneously. The star polycation (SPc) nanocarrier can act as an active ingredient to interact with virus coat protein via electrostatic interaction, which reduces the proportion of TMV particles to 2.9% and leads to a reduction of the amount of virus in the environment by half. SPc can act as an adjuvant to spontaneously assemble with an immune inducer lentinan (LNT) through hydrogen bonding into nanoscale (142 nm diameter) LNT/SPc complex, which improves the physicochemical property of LNT for better wetting performance on leaves and cellular uptake, and further activates plant immune responses. Finally, the LNT/SPc complex displays preventive and curative effects on TMV disease, reducing TMV-GFP relative expression by 26% in the laboratory and achieving 82% control efficacy in the field We hope the strategy reported here would be useful for control of crop virus disease.

GhMAC3e is involved in plant growth and defense response to Verticillium dahliae.

KEY MESSAGE: GhMAC3e expression was induced by various stresses and hormones. GhMAC3e may regulate plant growth by influencing auxin distribution, and play important roles in Verticillium wilt resistance via mediating SA signaling. The MOS4-Associated Complex (MAC) is a highly conserved protein complex involved in pre-mRNA splicing and spliceosome assembly, which plays a vital role in plant immunity. It comprises key components such as MOS4, CDC5, and PRL1. MAC3A/B, as U-box E3 ubiquitin ligases, are crucial for various plant processes including development, stress responses, and disease resistance. However, their roles in cotton remain largely unknown. In this study, we first cloned the GhMAC3e gene from cotton and explored its biological functions by using virus-induced gene silencing (VIGS) in cotton and transgenic overexpression in Arabidopsis. The results showed that GhMAC3e is ubiquitously expressed in cotton tissues and could be induced by salt stress, Verticillium dahliae (VD) infection, PEG, ABA, ETH, GA3, MeJA, and SA. Silencing GhMAC3e retarded primary stem growth and reduced biomass of cotton coupled with the reduced auxin content in the petioles and veins. Silencing GhMAC3e up-regulated expression of cell growth-related genes GhXTH16 and Gh3.6, while down-regulated GhSAUR12 expression. Ectopic expression of GhMAC3e in Arabidopsis significantly enhanced its resistance to Verticillium wilt (VW) in terms of decreased pathogen biomass and lowered plant mortality. Overexpression of GhMAC3e dramatically upregulated AtPR1 by around 15 fold and more than 262 fold under basal and VD inoculation condition, respectively. This change was not associated with the expression of GhNPR1. In conclusion, GhMAC3e may not only regulate plant growth by influencing auxin distribution and growth-related gene expression, but also play important roles in VW resistance via mediating SA signaling independent of NPR1 transcription level.

CRISPR/Cas9-Mediated Resistance to Wheat Dwarf Virus in Hexaploid Wheat (Triticum aestivum L.).

Wheat dwarf virus (WDV, genus Mastrevirus, family Geminiviridae) is one of the causal agents of wheat viral disease, which severely impacts wheat production in most wheat-growing regions in the world. Currently, there is little information about natural resistance against WDV in common wheat germplasms. CRISPR/Cas9 technology is being utilized to manufacture transgenic plants resistant to different diseases. In the present study, we used the CRISPR/Cas9 system targeting overlapping regions of coat protein (CP) and movement protein (MP) (referred to as CP/MP) or large intergenic region (LIR) in the wheat variety 'Fielder' to develop resistance against WDV. WDV-inoculated T1 progenies expressing Cas9 and sgRNA for CP/MP and LIR showed complete resistance against WDV and no accumulation of viral DNA compared with control plants. Mutation analysis revealed that the CP/MP and LIR targeting sites have small indels in the corresponding Cas9-positive plants. Additionally, virus inhibition and indel mutations occurred in T2 homozygous lines. Together, our work gives efficient results of the engineering of CRISPR/Cas9-mediated WDV resistance in common wheat plants, and the specific sgRNAs identified in this study can be extended to utilize the CRISPR/Cas9 system to confer resistance to WDV in other cereal crops such as barley, oats, and rye.

An Aegilops longissima NLR protein with integrated CC-BED module mediates resistance to wheat powdery mildew.

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), reduces wheat yields and grain quality, thus posing a significant threat to global food security. Wild relatives of wheat serve as valuable resources for resistance to powdery mildew. Here, the powdery mildew resistance gene Pm6Sl is cloned from the wild wheat species Aegilops longissima. It encodes a nucleotide-binding leucine-rich repeat (NLR) protein featuring a CC-BED module formed by a zinc finger BED (Znf-BED) domain integrated into the coiled-coil (CC) domain. The function of Pm6Sl is validated via mutagenesis, gene silencing, and transgenic assays. In addition, we develop a resistant germplasm harbouring Pm6Sl in a very small segment with no linkage drag along with the diagnostic gene marker pm6sl-1 to facilitate Pm6Sl deployment in wheat breeding programs. The cloning of Pm6Sl, a resistance gene with BED-NLR architecture, will increase our understanding of the molecular mechanisms underlying BED-NLR-mediated resistance to various pathogens.

Wild mungbean resistance to the nematode Meloidogyne enterolobii involves the induction of phenylpropanoid metabolism and lignification.

Root-knot nematodes (Meloidogyne spp.) are plant parasites causing annual economic losses amounting to several billion US dollars worldwide. One of the most aggressive species is M. enterolobii, a growing threat to agriculture due to its broad host range and ability to overcome many known resistance genes. Mungbean, a nutritionally and economically valuable crop, is particularly vulnerable to nematodes and pathogens. However, research focusing on mungbean resistance to M. enterolobii is scarce, and the corresponding defense mechanisms are poorly understood. Here, we screened mungbean accessions and identified an accession strongly resistant to M. enterolobii. Transcriptome analysis revealed 2730 differentially expressed genes (DEGs) in this resistant accession (CPI106939) compared to 1777 in the susceptible accession (Crystal) 7 days after nematode inoculation. The gene ontology (GO) upregulated in CPI106939 with functions related to plant-pathogen interactions, plant hormone signaling, oxidative stress, and plant immunity. Plant defense-related genes (WRKY, PAL, MAPK, POD and PR) were also significantly induced in CPI106939. Metabolome analysis showed that four secondary metabolites related to phenylpropanoid metabolism and lignification were significantly enriched in CPI106939. The induced immune response and secondary metabolites may underpin the enhanced resistance to M. enterolobii, providing insight into the resistance mechanisms in accession CPI106939 as well as candidate genes controlling the interaction between mungbean and its nematode parasite. Our study therefore provides foundations for the breeding of new varieties with intrinsic M. enterolobii resistance.

Integration of Transcriptomics and WGCNA to Characterize Trichoderma harzianum-Induced Systemic Resistance in Astragalus mongholicus for Defense against Fusarium solani.

Beneficial fungi of the genus Trichoderma are among the most widespread biocontrol agents that induce a plant's defense response against pathogens. Fusarium solani is one of the main pathogens that can negatively affect Astragalus mongholicus production and quality. To investigate the impact of Trichoderma harzianum on Astragalus mongholicus defense responses to Fusarium solani, A. mongholicus roots under T. harzianum + F. solani (T + F) treatment and F. solani (F) treatment were sampled and subjected to transcriptomic analysis. A differential expression analysis revealed that 6361 differentially expressed genes (DEGs) responded to T. harzianum induction. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the 6361 DEGs revealed that the genes significantly clustered into resistance-related pathways, such as the plant-pathogen interaction pathway, phenylpropanoid biosynthesis pathway, flavonoid biosynthesis pathway, isoflavonoid biosynthesis pathway, mitogen-activated protein kinase (MAPK) signaling pathway, and plant hormone signal transduction pathway. Pathway analysis revealed that the PR1, formononetin biosynthesis, biochanin A biosynthesis, and CHIB, ROS production, and HSP90 may be upregulated by T. harzianum and play important roles in disease resistance. Our study further revealed that the H2O2 content was significantly increased by T. harzianum induction. Formononetin and biochanin A had the potential to suppress F. solani. Weighted gene coexpression network analysis (WGCNA) revealed one module, including 58 DEGs associated with T. harzianum induction. One core hub gene, RPS25, was found to be upregulated by T. harzianum, SA (salicylic acid) and ETH (ethephon). Overall, our data indicate that T. harzianum can induce induced systemic resistance (ISR) and systemic acquired resistance (SAR) in A. mongholicus. The results of this study lay a foundation for a further understanding of the molecular mechanism by which T. harzianum induces resistance in A. mongholicus.

Research Progress on miRNAs and Artificial miRNAs in Insect and Disease Resistance and Breeding in Plants.

MicroRNAs (miRNAs) are small, non-coding RNAs that are expressed in a tissue- and temporal-specific manner during development. They have been found to be highly conserved during the evolution of different species. miRNAs regulate the expression of several genes in various organisms, with some regulating the expression of multiple genes with similar or completely unrelated functions. Frequent disease and insect pest infestations severely limit agricultural development. Thus, cultivating resistant crops via miRNA-directed gene regulation in plants, insects, and pathogens is an important aspect of modern breeding practices. To strengthen the application of miRNAs in sustainable agriculture, plant endogenous or exogenous miRNAs have been used for plant breeding. Consequently, the development of biological pesticides based on miRNAs has become an important avenue for future pest control methods. However, selecting the appropriate miRNA according to the desired target traits in the target organism is key to successfully using this technology for pest control. This review summarizes the progress in research on miRNAs in plants and other species involved in regulating plant disease and pest resistance pathways. We also discuss the molecular mechanisms of relevant target genes to provide new ideas for future research on pest and disease resistance and breeding in plants.

Puccinia triticina avirulence protein AvrLr21 directly interacts with wheat resistance protein Lr21 to activate wheat immune response.

Wheat leaf rust, caused by Puccinia triticina (Pt), remains a constant threat to wheat production worldwide. Deployment of race-specific leaf rust (Lr) resistance genes in wheat provides effective protection against leaf rust, but often leads to selective pressures that drive the rapid emergence of new virulent Pt isolates in nature. However, the molecular mechanisms underlying the evasion of Lr-delivered resistance by leaf rust remain largely unknown. Here, we identify an avirulence gene AvrLr21 in Pt that triggers Lr21-dependent immune responses. BSMV (Barley stripe mosaic virus)-mediated host-induced gene silencing assay shows that silencing AvrLr21 compromises Lr21-mediated immunity. AvrLr21 interacts directly with Lr21 protein to induce a hypersensitive response in tobacco leaves. The evolved Lr21-breaking Pt isolates can suppress Lr21-mediated immunity. Our data provide a basis for studying the molecular determinants in Pt-wheat incompatible interaction and monitoring natural Pt populations to prioritize the deployment of Lr resistance genes in the field.

Fluorinated plant activators induced dual-pathway signal transduction and long-lasting ROS burst in chloroplast.

Synthetic plant activators represent a promising novel class of green pesticides that can triggering endogenous plant immunity against pathogen invasion. In our previous study, we developed a series of fluorinated compounds capable of eliciting disease resistance in plants; however, the underlying regulatory mechanisms remained unclear. In this study, we systematically investigated the mechanism of plant immune activation using four synthetic plant activators in Arabidopsis thaliana (A. thaliana), including two fluorine-substituted and two non­fluorine-substituted molecules. Our findings revealed that the fluorinated compounds exhibited superior disease resistance activity compared to the non-fluorinated molecules. Gene expression analysis in systemic acquired resistance (SAR)- and induced systemic resistance (ISR)-related pathways demonstrated that fluorine substitution effectively regulated both SAR- and ISR-pathway activation, highlighting the distinct roles of fluorine in modulating the plant immune system. Notably, the prolonged ROS burst was observed in chloroplasts following treatment with all four plant activators, contrasting with the transient ROS burst induced by natural elicitors. These results provide insights into the unique mechanisms underlying synthetic plant activator-induced plant immunity. Furthermore, comprehensive proteomic analysis revealed a robust immune response mediated by fluorine-substituted plant activators. These findings offer novel insights into the role of fluorine substitution in SAR- and ISR-associated immune signaling pathways and their distinct impact on ROS production within chloroplasts.

SDE19, a SEC-dependent effector from 'Candidatus Liberibacter asiaticus' suppresses plant immunity and targets Citrus sinensis Sec12 to interfere with vesicle trafficking.

Citrus huanglongbing (HLB), which is caused by the phloem-colonizing bacteria Candidatus Liberibacter asiaticus (CLas), poses a significant threat to citrus production worldwide. The pathogenicity mechanism of HLB remains poorly understood. SEC-dependent effectors (SDEs) have been suggested to play critical roles in the interaction between citrus and CLas. Here, we explored the function of CLIBASIA_05320 (SDE19), a core SDE from CLas, and its interaction with its host target. Our data revealed that SDE19 is expressed at higher level during infection of citrus than that during infection of the Asian citrus psyllid. Subcellular localization assays showed that SDE19 is localized in the nucleus and cytoplasm and is capable of moving from cell to cell in Nicotiana benthamiana. To investigate whether SDE19 facilitates pathogen infection, we generated transgenic Arabidopsis thaliana and citrus plants overexpressing SDE19. Transgenic A. thaliana and citrus plants were more susceptible to Pseudomonas syringae pv. tomato (Pst) and Xanthomonas citri subsp. citri (Xcc), respectively. In addition, RNA-seq analysis demonstrated that overexpression of SDE19 resulted in a reprogramming of expression of genes related to biotic stimulus responses. SDE19 interacts with Citrus sinensis Sec12, a guanine nucleotide exchange factor responsible for the assembly of plant COPII (coat protein II)-coated vesicles, which mediate vesicle trafficking from the ER to the Golgi. SDE19 colocalizes with Sec12 in the ER by binding to its N-terminal catalytic region, affecting the stability of Sec12 through the 26S proteasome. This interaction hinders the secretion of apoplastic defense-related proteins such as PR1, P69B, GmGIP1, and RCR3. Furthermore, the secretion of PR1 and callose deposition is decreased in SDE19-transgenic A. thaliana. Taken together, SDE19 is a novel virulent SDE secreted by CLas that interacts with Sec12 to disrupt vesicle trafficking, inhibit defense-related proteins secretion, and promote bacterial infection. This study sheds light on how CLas manipulates the host vesicle trafficking pathway to suppress the secretion of defense-related proteins and interfere with plant immunity.

ACL1-ROC4/5 complex reveals a common mechanism in rice response to brown planthopper infestation and drought.

Brown planthopper (BPH) is the most destructive insect pest of rice. Drought is the most detrimental environmental stress. BPH infestation causes adaxial leaf-rolling and bulliform cells (BCs) shrinkage similar to drought. The BC-related abaxially curled leaf1 (ACL1) gene negatively regulates BPH resistance and drought tolerance, with decreased cuticular wax in the gain-of-function mutant ACL1-D. ACL1 shows an epidermis-specific expression. The TurboID system and multiple biochemical assays reveal that ACL1 interacts with the epidermal-characteristic rice outermost cell-specific (ROC) proteins. ROC4 and ROC5 positively regulate BPH resistance and drought tolerance through modulating cuticular wax and BCs, respectively. Overexpression of ROC4 and ROC5 both rescue ACL1-D mutant in various related phenotypes. ACL1 competes with ROC4/ROC5 in homo-dimer and hetero-dimer formation, and interacts with the repressive TOPLESS-related proteins. Altogether, we illustrate that ACL1-ROC4/5 complexes synergistically mediate drought tolerance and BPH resistance through regulating cuticular wax content and BC development in rice, a mechanism that might facilitate BPH-resistant breeding.

Comparative analysis of RNA interference and pattern-triggered immunity induced by dsRNA reveals different efficiencies in the antiviral response to potato virus X.

Antiviral responses induced by double-stranded RNA (dsRNA) include RNA interference (RNAi) and pattern-triggered immunity (PTI), but their relative contributions to antiviral defence are not well understood. We aimed at testing the impact of exogenous applied dsRNA on both layers of defence against potato virus X expressing GFP (PVX-GFP) in Nicotiana benthamiana. Co-inoculation of PVX-GFP with either sequence-specific (RNAi) or nonspecific dsRNA (PTI) showed that nonspecific dsRNA reduced virus accumulation in both inoculated and systemic leaves. However, nonspecific dsRNA was a poor inducer of antiviral immunity compared to a sequence-specific dsRNA capable of triggering the RNAi response, and plants became susceptible to systemic infection. Studies with a PVX mutant unable to move from cell to cell indicated that the interference with PVX-GFP triggered by nonspecific dsRNA operated at the single-cell level. Next, we performed RNA-seq analysis to examine similarities and differences in the transcriptome triggered by dsRNA alone or in combination with viruses harbouring sequences targeted or not by dsRNA. Enrichment analysis showed an over-representation of plant-pathogen signalling pathways, such as calcium, ethylene and MAPK signalling, which are typical of antimicrobial PTI. Moreover, the transcriptomic response to the virus targeted by dsRNA had a greater impact on defence than the non-targeted virus, highlighting qualitative differences between sequence-specific RNAi and nonspecific PTI responses. Together, these results further our understanding of plant antiviral defence, particularly the contribution of nonspecific dsRNA-mediated PTI. We envisage that both sequence-specific RNAi and nonspecific PTI pathways may be triggered via topical application of dsRNA, contributing cumulatively to plant protection against viruses.

Novel resistance loci for quantitative resistance to Septoria tritici blotch in Asian wheat (Triticum aestivum) via genome-wide association study.

BACKGROUND: Septoria tritici blotch (STB) disease causes yield losses of up to 50 per cent in susceptible wheat cultivars and can reduce wheat production. In this study, genomic architecture for adult-plant STB resistance in a Septoria Association Mapping Panel (SAMP) having 181 accessions and genomic regions governing STB resistance in a South Asian wheat panel were looked for. RESULTS: Field experiments during the period from 2019 to 2021 revealed those certain accessions, namely BGD52 (CHIR7/ANB//CHIR1), BGD54 (CHIR7/ANB//CHIR1), IND92 (WH 1218), IND8 (DBW 168), and IND75 (PBW 800), exhibited a high level of resistance. Genetic analysis revealed the presence of 21 stable quantitative trait nucleotides (QTNs) associated with resistance to STB (Septoria tritici blotch) on all wheat chromosomes, except for 2D, 3A, 3D, 4A, 4D, 5D, 6B, 6D, and 7A. These QTNs were predominantly located in chromosome regions previously identified as associated with STB resistance. Three Quantitative Trait Loci (QTNs) were found to have significant phenotypic effects in field evaluations. These QTNs are Q.STB.5A.1, Q.STB.5B.1, and Q.STB.5B.3. Furthermore, it is possible that the QTNs located on chromosomes 1A (Q.STB.1A.1), 2A (Q.STB_DH.2A.1, Q.STB.2A.3), 2B (Q.STB.2B.4), 5A (Q.STB.5A.1, Q.STB.5A.2), and 7B (Q.STB.7B.2) could potentially be new genetic regions associated with resistance. CONCLUSION: Our findings demonstrate the importance of Asian bread wheat as a source of STB resistance alleles and novel stable QTNs for wheat breeding programs aiming to develop long-lasting and wide-ranging resistance to Zymoseptoria tritici in wheat cultivars.

Withania somnifera osmotin (WsOsm) confers stress tolerance in tobacco and establishes novel interactions with the defensin protein (WsDF).

Pathogenesis-related proteins (PR), including osmotins, play a vital role in plant defense, being activated in response to diverse biotic and abiotic stresses. Despite their significance, the mechanistic insights into the role of osmotins in plant defense have not been extensively explored. The present study explores the cloning and characterization of the osmotin gene (WsOsm) from Withania somnifera, aiming to illuminate its role in plant defense mechanisms. Quantitative real-time PCR analysis revealed significant induction of WsOsm in response to various phytohormones e.g. abscisic acid, salicylic acid, methyl jasmonate, brassinosteroids, and ethrel, as well as biotic and abiotic stresses like heat, cold, salt, and drought. To further elucidate WsOsm's functional role, we overexpressed the gene in Nicotiana tabacum, resulting in heightened resistance against the Alternaria solani pathogen. Additionally, we observed enhancements in shoot length, root length, and root biomass in the transgenic tobacco plants compared to wild plants. Notably, the WsOsm- overexpressing seedlings demonstrated improved salt and drought stress tolerance, particularly at the seedling stage. Confocal histological analysis of H2O2 and biochemical studies of antioxidant enzyme activities revealed higher levels in the WsOsm overexpressing lines, indicating enhanced antioxidant defense. Furthermore, a pull-down assay and mass spectrometry analysis revealed a potential interaction between WsOsm and defensin, a known antifungal PR protein (WsDF). This suggests a novel role of WsOsm in mediating plant defense responses by interacting with other PR proteins. Overall, these findings pave the way for potential future applications of WsOsm in developing stress-tolerant crops and improving plant defense strategies against pathogens.