Showing papers on "Plant disease resistance published in 2022"

How do plants defend themselves against pathogens-Biochemical mechanisms and genetic interventions

Abstract: In agro-ecosystem, plant pathogens hamper food quality, crop yield, and global food security. Manipulation of naturally occurring defense mechanisms in host plants is an effective and sustainable approach for plant disease management. Various natural compounds, ranging from cell wall components to metabolic enzymes have been reported to protect plants from infection by pathogens and hence provide specific resistance to hosts against pathogens, termed as induced resistance. It involves various biochemical components, that play an important role in molecular and cellular signaling events occurring either before (elicitation) or after pathogen infection. The induction of reactive oxygen species, activation of defensive machinery of plants comprising of enzymatic and non-enzymatic antioxidative components, secondary metabolites, pathogenesis-related protein expression (e.g. chitinases and glucanases), phytoalexin production, modification in cell wall composition, melatonin production, carotenoids accumulation, and altered activity of polyamines are major induced changes in host plants during pathogen infection. Hence, the altered concentration of biochemical components in host plants restricts disease development. Such biochemical or metabolic markers can be harnessed for the development of "pathogen-proof" plants. Effective utilization of the key metabolites-based metabolic markers can pave the path for candidate gene identification. This present review discusses the valuable information for understanding the biochemical response mechanism of plants to cope with pathogens and genomics-metabolomics-based sustainable development of pathogen proof cultivars along with knowledge gaps and future perspectives to enhance sustainable agricultural production.

How do plants defend themselves against pathogens-Biochemical mechanisms and genetic interventions

Abstract: In agro-ecosystem, plant pathogens hamper food quality, crop yield, and global food security. Manipulation of naturally occurring defense mechanisms in host plants is an effective and sustainable approach for plant disease management. Various natural compounds, ranging from cell wall components to metabolic enzymes have been reported to protect plants from infection by pathogens and hence provide specific resistance to hosts against pathogens, termed as induced resistance. It involves various biochemical components, that play an important role in molecular and cellular signaling events occurring either before (elicitation) or after pathogen infection. The induction of reactive oxygen species, activation of defensive machinery of plants comprising of enzymatic and non-enzymatic antioxidative components, secondary metabolites, pathogenesis-related protein expression (e.g. chitinases and glucanases), phytoalexin production, modification in cell wall composition, melatonin production, carotenoids accumulation, and altered activity of polyamines are major induced changes in host plants during pathogen infection. Hence, the altered concentration of biochemical components in host plants restricts disease development. Such biochemical or metabolic markers can be harnessed for the development of "pathogen-proof" plants. Effective utilization of the key metabolites-based metabolic markers can pave the path for candidate gene identification. This present review discusses the valuable information for understanding the biochemical response mechanism of plants to cope with pathogens and genomics-metabolomics-based sustainable development of pathogen proof cultivars along with knowledge gaps and future perspectives to enhance sustainable agricultural production.

Long-read genome sequencing of bread wheat facilitates disease resistance gene cloning

Abstract: The cloning of agronomically important genes from large, complex crop genomes remains challenging. Here we generate a 14.7 gigabase chromosome-scale assembly of the South African bread wheat (Triticum aestivum) cultivar Kariega by combining high-fidelity long reads, optical mapping and chromosome conformation capture. The resulting assembly is an order of magnitude more contiguous than previous wheat assemblies. Kariega shows durable resistance to the devastating fungal stripe rust disease1. We identified the race-specific disease resistance gene Yr27, which encodes an intracellular immune receptor, to be a major contributor to this resistance. Yr27 is allelic to the leaf rust resistance gene Lr13; the Yr27 and Lr13 proteins show 97% sequence identity2,3. Our results demonstrate the feasibility of generating chromosome-scale wheat assemblies to clone genes, and exemplify that highly similar alleles of a single-copy gene can confer resistance to different pathogens, which might provide a basis for engineering Yr27 alleles with multiple recognition specificities in the future.

Aegilops sharonensis genome-assisted identification of stem rust resistance gene Sr62

Abstract: The wild relatives and progenitors of wheat have been widely used as sources of disease resistance (R) genes. Molecular identification and characterization of these R genes facilitates their manipulation and tracking in breeding programmes. Here, we develop a reference-quality genome assembly of the wild diploid wheat relative Aegilops sharonensis and use positional mapping, mutagenesis, RNA-Seq and transgenesis to identify the stem rust resistance gene Sr62, which has also been transferred to common wheat. This gene encodes a tandem kinase, homologues of which exist across multiple taxa in the plant kingdom. Stable Sr62 transgenic wheat lines show high levels of resistance against diverse isolates of the stem rust pathogen, highlighting the utility of Sr62 for deployment as part of a polygenic stack to maximize the durability of stem rust resistance.

OUP accepted manuscript

Abstract: Abstract In plants, long noncoding RNAs (lncRNAs) regulate disease resistance against fungi and other pathogens. However, the specific mechanism behind this regulation remains unclear. In this study, we identified disease resistance-related lncRNAs as well as their regulating genes and assessed their functions by infection of cotton (Gossypium) chromosome segment substitution lines with Verticillium dahliae. Our results demonstrated that lncRNA7 and its regulating gene Pectin methylesterase inhibitor 13 (GbPMEI13) positively regulated disease resistance via the silencing approach, while ectopic overexpression of GbPMEI13 in Arabidopsis (Arabidopsis thaliana) promoted growth and enhanced resistance to V. dahliae. In contrast, lncRNA2 and its regulating gene Polygalacturonase 12 (GbPG12) negatively regulated resistance to V. dahliae. We further found that fungal disease-related agents, including the pectin-derived oligogalacturonide (OG), could downregulate the expression of lncRNA2 and GbPG12, leading to pectin accumulation. Conversely, OG upregulated the expression of lncRNA7, which encodes a plant peptide phytosulfokine (PSK-α), which was confirmed by lncRNA7 overexpression and Ultra Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS) experiments. We showed that PSK-α promoted 3-Indoleacetic acid (IAA) accumulation and activated GbPMEI13 expression through Auxin Response Factor 5. Since it is an inhibitor of pectin methylesterase (PME), GbPMEI13 promotes pectin methylation and therefore increases the resistance to V. dahliae. Consistently, we also demonstrated that GbPMEI13 inhibits the mycelial growth and spore germination of V. dahliae in vitro. In this study, we demonstrated that lncRNA7, lncRNA2, and their regulating genes modulate cell wall defense against V. dahliae via auxin-mediated signaling, providing a strategy for cotton breeding.

Overexpression of VqWRKY31 enhances powdery mildew resistance in grapevine by promoting salicylic acid signaling and specific metabolite synthesis

Abstract: Abstract Powdery mildew (PM), caused by the fungal pathogen Erysiphe necator, is one of the most destructive diseases of grapevine (Vitis vinifera and other Vitis spp.). Resistance to PM is an important goal for cultivar improvement, and understanding the underlying molecular mechanisms conditioning resistance is critical. Here, we report that transgenic expression of the WRKY transcription factor gene VqWRKY31 from the PM-resistant species Vitis quinquangularis conferred resistance to PM in V. vinifera through promoting salicylic acid signaling and specific metabolite synthesis. VqWRKY31 belongs to the WRKY IIb subfamily, and expression of the VqWRKY31 gene was induced in response to E. necator inoculation. Transgenic V. vinifera plants expressing VqWRKY31 were substantially less susceptible to E. necator infection, and this was associated with increased levels of salicylic acid and reactive oxygen species. Correlation analysis of transcriptomic and metabolomic data revealed that VqWRKY31 promoted expression of genes in metabolic pathways and the accumulation of many disease resistance-related metabolites, including stilbenes, flavonoids, and proanthocyanidins. In addition, results indicated that VqWRKY31 can directly bind to the promoters of two structural genes in stilbene synthesis, STS9 and STS48, and activate their expression. Based on our results, we propose a model where VqWRKY31 enhances grapevine PM resistance through activation of salicylic acid defense signaling and promotion of specific disease resistance-related metabolite synthesis. These findings can be directly exploited for molecular breeding strategies to produce PM-resistant grapevine germplasm.

Cotton long non-coding RNAs regulate cell wall defense genes and strengthen resistance to Verticillium wilt.

Abstract: In plants, long non-coding RNAs regulate disease resistance against fungi and other pathogens. However, the specific mechanism behind this regulation remains unclear. In this study, we identified disease resistance-related lncRNAs as well as their regulating genes and assessed their functions by infection of cotton (Gossypium) chromosome segment substitution lines with Verticillium dahliae. Our results demonstrated that lncRNA7 and its regulating gene Pectin methylesterase inhibitor 13 (GbPMEI13) positively regulated disease resistance via the silencing approach, while ectopic overexpression of GbPMEI13 in Arabidopsis (Arabidopsis thaliana) promoted growth and enhanced resistance to V. dahliae. In contrast, lncRNA2 and its regulating gene Polygalacturonase 12 (GbPG12) negatively regulated resistance to V. dahliae. We further found that fungal disease-related agents, including the pectin-derived oligogalacturonide (OG), could down-regulate the expression of lncRNA2 and GbPG12, leading to pectin accumulation. Conversely, OG up-regulated the expression of lncRNA7, which encodes a plant peptide phytosulfokine (PSK-α), which was confirmed by lncRNA7 overexpression and UPLC-MS experiments. We showed that PSK-α promoted IAA accumulation and activated GbPMEI13 expression through Auxin Response Factor 5 (ARF5). Since it is an inhibitor of pectin methylesterase (PME), GbPMEI13 promotes pectin methylation and therefore increases the resistance to V. dahliae. Consistently, we also demonstrated that GbPMEI13 inhibits the mycelial growth and spore germination of V. dahliae in vitro. In this study, we demonstrated that lncRNA7, lncRNA2, and their regulating genes modulate cell wall defense against V. dahliae via auxin-mediated signaling, providing a strategy for cotton breeding.

OUP accepted manuscript

Abstract: Abstract Melatonin is an essential phytohormone in the regulation of many plant processes, including during plant development and in response to stress. Pathogen infections cause serious damage to plants and reduce agricultural production. Recent studies indicate that melatonin plays important roles in alleviating bacterial, fungal, and viral diseases in plants and post-harvest fruits. Herein, we summarize information related to the effects of melatonin on plant disease resistance. Melatonin, reactive oxygen species, and reactive nitrogen species form a complex loop in plant–pathogen interaction to regulate plant disease resistance. Moreover, crosstalk of melatonin with other phytohormones including salicylic acid, jasmonic acid, auxin, and abscisic acid further activates plant defense genes. Melatonin plays an important role not only in plant immunity but also in alleviating pathogenicity. We also summarize the known processes by which melatonin mediates pathogenicity via negatively regulating the expression levels of genes related to cell viability as well as virulence-related genes. The multiple mechanisms underlying melatonin influences on both plant immunity and pathogenicity support the recognition of the essential nature of melatonin in plant–pathogen interactions, highlighting phytomelatonin as a critical molecule in plant immune responses.

Phytomelatonin as a central molecule in plant disease resistance.

Abstract: Melatonin is an essential phytohormone in the regulation of many plant processes, including both during plant development and in response to stress. Pathogen infections cause serious damage to plants and reduce agricultural production. Recent studies indicate that melatonin plays important roles in alleviating bacterial, fungal and viral diseases in plants and post-harvest fruits. Herein, we summarize information related to the effects of melatonin on plant disease resistance. Melatonin, reactive oxygen species (ROS) and reactive nitrogen species (RNS) form a complex loop during plant-pathogen interaction to regulate plant disease resistance. Moreover, melatonin also has crosstalk with other phytohormones including salicylic acid (SA), jasmonic acid (JA), auxin, abscisic acid (ABA) which further activates plant defense genes. Melatonin not only plays an important role in plant immunity, but also in alleviating pathogen pathogenicity. We also summarize the known processes by which melatonin mediates pathogen pathogenicity via negatively regulating the expression levels of genes related to cell viability as well as virulence-related genes. The multiple mechanisms underlying melatonin influences on both plant immunity and pathogen pathogenicity support the recognition of the essential nature of melatonin in plant-pathogen interactions, highlighting phytomelatonin as a critical molecule in plant immune responses.

Unraveling Microbial Volatile Elicitors Using a Transparent Methodology for Induction of Systemic Resistance and Regulation of Antioxidant Genes at Expression Levels in Chili against Bacterial Wilt Disease

Abstract: Microbial volatiles benefit the agricultural ecological system by promoting plant growth and systemic resistance against diseases without harming the environment. To explore the plant growth-promoting efficiency of VOCs produced by Pseudomonas fluorescens PDS1 and Bacillus subtilis KA9 in terms of chili plant growth and its biocontrol efficiency against Ralstonia solanacearum, experiments were conducted both in vitro and in vivo. A closure assembly was designed using a half-inverted plastic bottle to demonstrate plant–microbial interactions via volatile compounds. The most common volatile organic compounds were identified and reported; they promoted plant development and induced systemic resistance (ISR) against wilt pathogen R. solanacearum. The PDS1 and KA9 VOCs significantly increased defensive enzyme activity and overexpressed the antioxidant genes PAL, POD, SOD, WRKYa, PAL1, DEF-1, CAT-2, WRKY40, HSFC1, LOX2, and NPR1 related to plant defense. The overall gene expression was greater in root tissue as compared to leaf tissue in chili plant. Our findings shed light on the relationship among rhizobacteria, pathogen, and host plants, resulting in plant growth promotion, disease suppression, systemic resistance-inducing potential, and antioxidant response with related gene expression in the leaf and root tissue of chili.

The genome of the rice variety LTH provides insight into its universal susceptibility mechanism to worldwide rice blast fungal strains

Abstract: The widely used rice variety Lijiangxintuanheigu (LTH) shows a universal susceptibility to thousands of Magnaporthe oryzae isolates, the causal agent of devastating rice blast, making LTH an ideal line in resistance (R) gene cloning. However, the underlying genetic mechanism of the universal susceptibility has not been fully revealed because of the lack of a high-quality genome. Here, we took a genomic approach together with experimental assays to investigate LTH's universal susceptibility to rice blast. Using Nanopore long reads, we assembled a chromosome-level genome. Millions of genomic variants were detected by comparing LTH with 10 other rice varieties, of which large-effect variants could affect plant immunity. Gene family analyses show that the number of R genes and leucine-rich repeat receptor-like protein kinase (LRR-RLK)-encoding genes decrease significantly in LTH. Rice blast resistance genes called Pi genes are either absent or disrupted by genomic variations. Additionally, residual R genes of LTH are likely under weak pathogen selection pressure, and other plant defense-related genes are weakly induced by rice blast. In contrast, the pattern-triggered immunity (PTI) of LTH is normal, as demonstrated by experimental assays. Therefore, we conclude that weak effector-trigger immunity (ETI)-mediated primarily by Pi genes but not PTI results in the universal susceptibility of LTH to rice blast. The attenuated ETI of LTH may be also associated with reduced numbers of R genes and LRR-RLKs, and minimally functional residual defense-related genes. Finally, we demonstrate the use of the LTH genome by rapid cloning of the Pi gene Piak from a resistant variety.

Defense Strategies: The Role of Transcription Factors in Tomato–Pathogen Interaction

Abstract: Simple Summary Tomato is one of the most cultivated and economically important vegetable crops throughout the world. It is affected by a panoply of different pathogens that cause infectious diseases that reduce tomato yield and affect product quality, with the most common symptoms being wilts, leaf spots/blights, fruit spots, and rots. To survive, tomato, as other plants, have developed elaborate defense mechanisms against plant pathogens. Among several genes already identified in tomato response to pathogens, we highlight those encoding the transcription factors (TFs). TFs are regulators of gene expression and are involved in large-scale biological phenomena. Here, we present an overview of recent studies of tomato TFs regarding defense responses to pathogen attack, selected for their abundance, importance, and availability of functionally well-characterized members. Tomato TFs’ roles and the possibilities related to their use for genetic engineering in view of crop breeding are presented. Abstract Tomato, one of the most cultivated and economically important vegetable crops throughout the world, is affected by a panoply of different pathogens that reduce yield and affect product quality. The study of tomato–pathogen system arises as an ideal system for better understanding the molecular mechanisms underlying disease resistance, offering an opportunity of improving yield and quality of the products. Among several genes already identified in tomato response to pathogens, we highlight those encoding the transcription factors (TFs). TFs act as transcriptional activators or repressors of gene expression and are involved in large-scale biological phenomena. They are key regulators of central components of plant innate immune system and basal defense in diverse biological processes, including defense responses to pathogens. Here, we present an overview of recent studies of tomato TFs regarding defense responses to biotic stresses. Hence, we focus on different families of TFs, selected for their abundance, importance, and availability of functionally well-characterized members in response to pathogen attack. Tomato TFs’ roles and possibilities related to their use for engineering pathogen resistance in tomato are presented. With this review, we intend to provide new insights into the regulation of tomato defense mechanisms against invading pathogens in view of plant breeding.

Discovery of stripe rust resistance with incomplete dominance in wild emmer wheat using bulked segregant analysis sequencing

Abstract: Abstract Durable crop disease resistance is an essential component of global food security. Continuous pathogen evolution leads to a breakdown of resistance and there is a pressing need to characterize new resistance genes for use in plant breeding. Here we identified an accession of wild emmer wheat ( Triticum turgidum ssp. dicoccoides ), PI 487260, that is highly resistant to multiple stripe rust isolates. Genetic analysis revealed resistance was conferred by a single, incompletely dominant gene designated as Yr84 . Through bulked segregant analysis sequencing (BSA-Seq) we identified a 52.7 Mb resistance-associated interval on chromosome 1BS. Detected variants were used to design genetic markers for recombinant screening, further refining the interval of Yr84 to a 2.3–3.3 Mb in tetraploid wheat genomes. This interval contains 34 candidate genes encoding for protein domains involved in disease resistance responses. Furthermore, KASP markers closely-linked to Yr84 were developed to facilitate marker-assisted selection for rust resistance breeding.

Understanding the Dynamics of Blast Resistance in Rice-Magnaporthe oryzae Interactions

Abstract: Rice is a global food grain crop for more than one-third of the human population and a source for food and nutritional security. Rice production is subjected to various stresses; blast disease caused by Magnaporthe oryzae is one of the major biotic stresses that has the potential to destroy total crop under severe conditions. In the present review, we discuss the importance of rice and blast disease in the present and future global context, genomics and molecular biology of blast pathogen and rice, and the molecular interplay between rice–M. oryzae interaction governed by different gene interaction models. We also elaborated in detail on M. oryzae effector and Avr genes, and the role of noncoding RNAs in disease development. Further, rice blast resistance QTLs; resistance (R) genes; and alleles identified, cloned, and characterized are discussed. We also discuss the utilization of QTLs and R genes for blast resistance through conventional breeding and transgenic approaches. Finally, we review the demonstrated examples and potential applications of the latest genome-editing tools in understanding and managing blast disease in rice.

Ancient variation of the AvrPm17 gene in powdery mildew limits the effectiveness of the introgressed rye Pm17 resistance gene in wheat

Abstract: Significance Domesticated and wild wheat relatives provide an important source of new immune receptors for wheat resistance breeding against fungal pathogens. The durability of these resistance genes is variable and difficult to predict, yet it is crucial for effective resistance breeding. We identified a fungal effector protein recognized by an immune receptor introgressed from rye to wheat. We found that variants of the effector allowing the fungus to overcome the resistance are ancient. They were already present in the wheat powdery mildew gene pool before the introgression of the immune receptor and are therefore responsible for the rapid resistance breakdown. Our study demonstrates that the effort to identify durable resistance genes cannot be dissociated from studies of pathogen avirulence genes.

Breeding for disease resistance in soybean: a global perspective

Abstract: This review provides a comprehensive atlas of QTLs, genes, and alleles conferring resistance to 28 important diseases in all major soybean production regions in the world. Breeding disease-resistant soybean [Glycine max (L.) Merr.] varieties is a common goal for soybean breeding programs to ensure the sustainability and growth of soybean production worldwide. However, due to global climate change, soybean breeders are facing strong challenges to defeat diseases. Marker-assisted selection and genomic selection have been demonstrated to be successful methods in quickly integrating vertical resistance or horizontal resistance into improved soybean varieties, where vertical resistance refers to R genes and major effect QTLs, and horizontal resistance is a combination of major and minor effect genes or QTLs. This review summarized more than 800 resistant loci/alleles and their tightly linked markers for 28 soybean diseases worldwide, caused by nematodes, oomycetes, fungi, bacteria, and viruses. The major breakthroughs in the discovery of disease resistance gene atlas of soybean were also emphasized which include: (1) identification and characterization of vertical resistance genes reside rhg1 and Rhg4 for soybean cyst nematode, and exploration of the underlying regulation mechanisms through copy number variation and (2) map-based cloning and characterization of Rps11 conferring resistance to 80% isolates of Phytophthora sojae across the USA. In this review, we also highlight the validated QTLs in overlapping genomic regions from at least two studies and applied a consistent naming nomenclature for these QTLs. Our review provides a comprehensive summary of important resistant genes/QTLs and can be used as a toolbox for soybean improvement. Finally, the summarized genetic knowledge sheds light on future directions of accelerated soybean breeding and translational genomics studies.

Trehalose increases tomato drought tolerance, induces defenses, and increases resistance to bacterial wilt disease

Abstract: Ralstonia solanacearum causes bacterial wilt disease, leading to severe crop losses. Xylem sap from R . solanacearum -infected tomato is enriched in the disaccharide trehalose. Water-stressed plants also accumulate trehalose, which increases drought tolerance via abscisic acid (ABA) signaling. Because R . solanacearum -infected plants suffer reduced water flow, we hypothesized that bacterial wilt physiologically mimics drought stress, which trehalose could mitigate. We found that R . solanacearum -infected plants differentially expressed drought-associated genes, including those involved in ABA and trehalose metabolism, and had more ABA in xylem sap. Consistent with this, treating tomato roots with ABA reduced both stomatal conductance and stem colonization by R . solanacearum . Treating roots with trehalose increased xylem sap ABA and reduced plant water use by lowering stomatal conductance and temporarily improving water use efficiency. Trehalose treatment also upregulated expression of salicylic acid (SA)-dependent tomato defense genes; increased xylem sap levels of SA and other antimicrobial compounds; and increased bacterial wilt resistance of SA-insensitive NahG tomato plants. Additionally, trehalose treatment increased xylem concentrations of jasmonic acid and related oxylipins. Finally, trehalose-treated plants were substantially more resistant to bacterial wilt disease. Together, these data show that exogenous trehalose reduced both water stress and bacterial wilt disease and triggered systemic disease resistance, possibly through a Damage Associated Molecular Pattern (DAMP) response pathway. This suite of responses revealed unexpected linkages between plant responses to biotic and abiotic stress and suggested that R . solanacearum- infected plants increase trehalose to improve water use efficiency and increase wilt disease resistance. The pathogen may degrade trehalose to counter these efforts. Together, these results suggest that treating tomatoes with exogenous trehalose could be a practical strategy for bacterial wilt management.

Pathogen-induced biosynthetic pathways encode defense-related molecules in bread wheat

Abstract: Significance Wheat is a globally important food crop that suffers major yield losses due to outbreaks of severe disease. A better mechanistic understanding of how wheat responds to pathogen attack could identify new strategies for enhancing disease resistance. Here, we discover six pathogen-induced biosynthetic pathways that share a common regulatory network and form part of an orchestrated defense response. Investigation of the wheat genome reveals that these pathways are each encoded by biosynthetic gene clusters (BGCs). We further show that these BGCs produce flavonoids and terpenes that may serve as phytoalexins or defense-related signaling molecules. Our results provide key insights into the molecular basis of biotic stress responses in wheat and open potential avenues for crop improvement.

Osa‐miR535 targets SQUAMOSA promoter binding protein‐like 4 to regulate blast disease resistance in rice

Abstract: SUMMARY Many rice microRNAs have been identified as fine‐tuning factors in the regulation of agronomic traits and immunity. Among them, Osa‐miR535 targets SQUAMOSA promoter binding protein‐like 14 (OsSPL14) to positively regulate tillers but negatively regulate yield and immunity. Here, we uncovered that Osa‐miR535 targets another SPL gene, OsSPL4, to suppress rice immunity against Magnaporthe oryzae. Overexpression of Osa‐miR535 significantly decreased the accumulation of the fusion protein SPL4TBS‐YFP that contains the target site of Osa‐miR535 in OsSPL4. Consistently, Osa‐miR535 mediated the cleavage of OsSPL4 mRNA between the 10th and 11th base pair of the predicted binding site at the 3′ untranslated region. Transgenic rice lines overexpressing OsSPL4 (OXSPL4) displayed enhanced blast disease resistance accompanied by enhanced immune responses, including increased expression of defense‐relative genes and up‐accumulated H2O2. By contrast, the knockout mutant osspl4 exhibited susceptibility. Moreover, OsSPL4 binds to the promoter of GH3.2, an indole‐3‐acetic acid‐amido synthetase, and promotes its expression. Together, these data indicate that Os‐miR535 targets OsSPL4 and OsSPL4‐GH3.2, which may parallel the OsSPL14‐WRKY45 module in rice blast disease resistance.

Ethylene‐responsive factor ERF114 mediates fungal pathogen effector PevD1‐induced disease resistance in Arabidopsis thaliana

Abstract: Abstract APETALA2/ethylene‐responsive factor (AP2/ERF) family transcription factors are well‐documented in plant responses to a wide range of biotic and abiotic stresses, but their roles in mediating elicitor‐induced disease resistance remains largely unexplored. PevD1 is a Verticillium dahliae secretory effector that can induce disease resistance in cotton and tobacco plants. In our previous work, Nicotiana benthamiana ERF114 (NbERF114) was identified in a screen of genes differentially expressed in response to PevD1 infiltration. Here, we found that the ortholog of NbERF114 in Arabidopsis thaliana (ERF114) also strongly responded to PevD1 treatment and transcripts were induced by Pseudomonas syringae pv. tomato (Pst) DC3000 infection. Loss of ERF114 function caused impaired disease resistance, while overexpressing ERF114 (OE‐ERF114) enhanced resistance to Pst DC3000. Moreover, ERF114 mediated PevD1‐induced disease resistance. RNA‐sequencing analysis revealed that the transcript level of phenylalanine ammonia‐lyase1 (PAL1) and its downstream genes were significantly suppressed in erf114 mutants compared with A. thaliana Col‐0. Reverse transcription‐quantitative PCR (RT‐qPCR) analysis further confirmed that the PAL1 mRNA level was significantly elevated in overexpressing OE‐ERF114 plants but reduced in erf114 mutants compared with Col‐0. Chromatin immunoprecipitation‐qPCR (ChIP‐qPCR) and electrophoretic mobility shift assay verified that ERF114 directly bound to the promoter of PAL1. The gene expression profiles of ERF114 and PAL1 in oestradiol‐inducible transgenic plants confirmed ERF114 could activate PAL1 transcriptional expression. Further investigation revealed that ERF114 positively modulated PevD1‐induced lignin and salicylic acid accumulation, probably by activating PAL1 transcription.

Alginate-Induced Disease Resistance in Plants

Abstract: Plants are continuously exposed to a wide range of pathogens, including fungi, bacteria, nematodes, and viruses; therefore, survival under these conditions requires a sophisticated defense system. The activation of defense responses and related signals in plants is regulated mainly by the hormones salicylic acid, jasmonic acid, and ethylene. Resistance to pathogen infection can be induced in plants by various biotic and abiotic agents. For many years, the use of abiotic plant resistance inducers has been considered in integrated disease management programs. Recently, natural inducer compounds, such as alginates, have become a focus of interest due to their environmentally friendly nature and their ability to stimulate plant defense mechanisms and enhance growth. Polysaccharides and the oligosaccharides derived from them are examples of eco-compatible compounds that can enhance plant growth while also inducing plant resistance against pathogens and triggering the expression of the salicylic acid-dependent defense pathway.