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Amino acid transporters (AATs) have been shown to be involved in immune responses during plant–pathogen interactions; however, the molecular mechanism by which they function in this process remains unclear. Here, we used a joint analysis of a genome-wide association study and quantitative trait locus (QTL) mapping to identify MEMBRANE PROTEIN 1 , which acts as a QTL in rice against blast fungus. Heterogeneous expression of OsMP1 in yeast supported its function in transporting a wide range of amino acids, including Thr, Ser, Phe, His, and Glu. OsMP1 could also mediate 15N-Glu efflux and influx in Xenopus oocyte cells. The expression of OsMP1 was significantly induced by Magnaporthe oryzae in the resistant rice landrace Heikezijing, whereas no such induction was observed in the susceptible landrace Suyunuo. Overexpressing OsMP1 in Suyunuo enhanced disease resistance to blast fungus and leaf blight bacterium without resulting in a yield penalty. In addition, the overexpression of OsMP1 led to increased accumulation of Thr, Ser, Phe, and His in the leaves and this contributed to the reduced disease susceptibility, which was associated with up-regulation of the jasmonic acid pathway. Our results demonstrate the important role of OsMP1 in disease resistance in rice and provide a potential target for breeding more resistant cultivars without reducing yield. [ABSTRACT FROM AUTHOR]

The Nascent polypeptide‐Associated Complex (NAC) family is among the largest plant‐specific TF families and plays an important role in plant growth, development, and stress responses.NAC TFs have been extensively studied in plants such as rice and Arabidopsis; however, their characterization, functions, evolution, and expression patterns in Manihot esculenta (cassava) under environmental stress remain largely unexplored. Here, we used bioinformatic analyses and biotic stress responses to investigate the physicochemical properties, chromosome location, phylogeny, gene structure, expression patterns, and cis‐elements in promoter regions of the NAC TFs in cassava.We identified 119 M. esculenta NAC (MeNAC) gene families, unevenly distributed on 16 chromosomes. We investigated expression patterns of all identified MeNAC TFs under Xanthomonas axonopodis pv. manihotis (Xam) infection, strain CHN11, at different time points. Only 20 MeNAC TFs showed expression of significant bacterial resistance. Six MeNACs (MeNAC7, 26, 63, 65, 77, and 113) were selected for functional analysis. qRT‐PCR assays revealed that MeNAC7, 26, 63, 65, 77, and 113 were induced in response to XamCHN11 infection and may participate in the molecular interaction of cassava and bacterial blight. Interestingly, MeNAC26, MeNAC63, MeNAC65, and MeNAC113 responded to XamCHN11 infection at 3 h post‐inoculation. Furthermore, we identified 13 stress‐related cis‐elements in promoter regions of the MeNAC genes that are involved in diverse environmental stress responses. Phylogenetic analysis revealed that MeNAC genes with similar structures and motif distributions were grouped.This study provides valuable insights into the evolution, diversity, and characterization of MeNAC TFs. It lays the groundwork for a better understanding of their biological roles and molecular mechanisms in cassava. [ABSTRACT FROM AUTHOR]

The detection of rice leaf disease is an essential step for implementing precise and timely interventions, thereby mitigating the spread and minimizing the ecological and economic consequences. This work proposes a deep learning-based biotic rice leaf disease detection model wherein ensemble models have been proposed using pre-trained models as feature extractors and machine learning/deep learning classifiers for performing classification. VGG16, SqueezeNet, and InceptionV3, have been used as feature extractors. The fine-tuning of various pre-trained models has been done by setting the hyperparameters to the prominent values for achieving optimal results. These hyperparameters include batch size, learning rate, optimizer, epochs, train, and test ratio. The model utilizes various machine learning and deep learning classifiers to perform the multiclass classification on extracted features from a pooled rice leaf disease dataset. In the proposed work, SqueezeNet with neural network classifier achieved the highest accuracy of 93.3%, Area Under Curve (AUC) of 0.989, precision of 0.928, recall of 0.931, and F1-score of 0.928. [ABSTRACT FROM AUTHOR]

Rice spotted-leaf mutants serve as valuable resources for studying plant programmed cell death (PCD) and disease resistance mechanisms, making them crucial for research on disease resistance in rice. Map-based cloning was used to identify and clone the spotted-leaf gene OsSPL42. Then, functional complementation and CRISPR/Cas9 techniques were also employed to further validate the function of this gene. By applying leaf clippings for bacterial blight (BB) inoculation, the BB resistance of different rice lines was assessed. The results in this study were as follows: The OsSPL42 behaved as a recessive nuclear gene and was narrowed down to a 111 kb region on chromosome 8. All T0 transgenic rice plants in the complementation experiments exhibited a wild-type phenotype, without any lesion spots on the rice leaves. This suggests that the LOC_Os08g06100 encoding O-methyltransferase is the candidate gene for the mutant spl42. The OsSpl42 is widely expressed and the OsSPL42-GFP protein is mainly localized in the cytoplasm. OsSPL42 overexpression lines are more susceptible to BBs, which indicates that OsSPL42 may act as a negative regulator of rice resistance to BB. In summary, we speculate that OsSPL42 plays an important role in the regulation of pathogen response, providing new insights into plant defense mechanisms. [ABSTRACT FROM AUTHOR]

Xanthomonas oryzae pv. oryzae (Xoo) poses a major risk to worldwide rice cultivation due to its ability to cause bacterial blight (BB). Identifying the Xoo race patterns, and using resistant genes specific to a particular race is a promising strategy to develop varieties with durable resistance. In the present research, 300 Xoo isolates were confirmed and purified from 40 rice-producing areas of Bangladesh to determine the existing races/pathotypes of Xoo. The sensitive rice varieties IR24, BRRI dhan49, and Purbachi showed susceptible reactions against the tested isolates. Fourteen monogenic differentials and 18 pyramid lines were challenged against 300 isolates of Xoo. Bacterial blight resistance genes Xa1, Xa2, Xa3, Xa4, xa5, Xa7, xa8, Xa10, Xa11, xa13, Xa14, Xa21, Xa23, and Xa27 were found in each monogenic differential. By analyzing patterns of the reaction of 300 Xoo isolates on monogenic differentials, 13 pathotypes/races were determined. The effectiveness of the host plant R genes Xa4, xa5, Xa7, xa8, Xa10, xa13, Xa14, Xa21, and Xa27 against bacterial blight has been determined by analyzing frequency resistances and the responses of near isogenic and pyramid lines. Races 1, 3, and 6 were dominantly widespread across the country and were regarded as important races since they had the greatest number of isolates (25%, 23.33%, and 9.67% respectively). Race 2 was the most ubiquitous among the pathotypes, whereas Race 3 was the most virulent, having circumvented every evaluated resistance gene. The bacterial-blight resistant R genes Xa21 and Xa27 have shown resistance against eight and ten races out of thirteen different races, respectively (i.e., 54.7 and 44.3% of the isolates tested). In the evaluation of 50 pyramid lines against the 5 most virulent races, the combinations of Xa4, Xa7, xa13, and Xa21 or the combinations of Xa4, xa5, Xa7, xa13, and Xa21 genes were effective. At present, the suitable and effective R genes i.e., xa5, Xa7, xa8, xa13, Xa21, Xa23, and Xa27 could be utilized for the development of a durable BB-resistant variety in Bangladesh. [ABSTRACT FROM AUTHOR]

Xylophilus ampelinus is a xylematic bacterium causing bacterial blight of grapevine, a disease regarded as a potential threat for viticulture in several countries. Currently, PCR detection is pivotal in diagnostic protocols due to the bacterium's infrequent occurrence in the field and the technical advantages of PCR. Recent metagenomic studies have unveiled diversity in its taxonomic domain, unknown when the most widely used assays for the detection of X. ampelinus infections were developed. In particular, PCR assays relying on highly conserved sequence regions, such as those surrounding ribosomal RNA genes, may be substituted with more specific PCR assays. In this study, we first investigated the diversity of detectable grapevine endophytes related to but different from X. ampelinus and delineated the genotaxonomic boundaries of the species in relation to the known (meta)genomes of closely related bacteria. Then, by exploiting the wealth of genomes now available for bacteria classified in the Burkholderiales, we devised several sets of primers targeting only X. ampelinus and its closest relatives. These primers were employed to (i) genotaxonomically circumscribe the grapevine endophyte species related to but distinguishable from X. ampelinus and (ii) develop a robust multiplex PCR assay expected to be specific for the species X. ampelinus based on in vitro and in silico evidence. The adoption of the multiplex PCR assay presented here is expected to reduce the risk of false positives in the diagnosis of bacterial blight of grapevine. [ABSTRACT FROM AUTHOR]

Abstract The bacterial blight of wheat is an important global disease causing a significant decline in crop yield. Nanotechnology offers a potential solution for managing plant diseases. Therefore, this research aimed to investigate the effectiveness of silver nanoparticles (AgNPs) in controlling bacterial blight in 27 locally grown wheat cultivars. The study examined the impact of AgNPs at three distinct time points: 1, 3, and 5 days after the onset of the disease. Biochemical assay revealed that one day after applying the disease stress, the Inia cultivar had the highest amount of soluble protein (55.60 μg.g−1FW) content in the treatment without AgNPs. The Azadi cultivar, without AgNPs treatment, had the lowest amount of soluble protein content (15.71 μg.g−1FW). The Tabasi cultivar had the highest activity of the superoxide dismutase (SOD) (61.62 mM.g−1FW) with the combination treatment of AgNPs. On the other hand, the Karchia cultivar had the lowest SOD activity (0.6 mM.g−1FW) in the treatment of disease without AgNPs. Furthermore, three days after the application of stress, the Mahdavi cultivar had the highest amount of soluble protein content (54.16 μg.g−1FW) in the treatment of disease without AgNPs. The Niknejad cultivar had the highest activity of the SOD (74.15 mM.g−1FW) with the combined treatment of the disease without AgNPs. The Kavir cultivar had the lowest SOD activity (1.95 mM.g−1FW) and the lowest peroxidase (POX) activity (0.241 mM g−1FW min−1) in the treatment of the disease with AgNPs. Five days after exposure to stress, the Mahooti cultivar had the highest SOD activity (88.12 mM.g−1FW) with the combined treatment of the disease with AgNPs, and the Karchia cultivar had the lowest SOD activity (2.39 mM.g−1FW) in the treatment of the disease with AgNPs. Further, the results indicated that exposure to AgNPs could improve the antioxidant properties of wheat seeds in blight-infected and disease-free conditions in some cultivars.

The current study was carried out to assess the alkaloid‐enriched constituents of Prosopis juliflora (Fabaceae) against bacterial blight of pomegranate. Utilising plant extracts for disease management offers an eco‐friendly approach. In vitro assessment of the minimum inhibitory concentration (MIC) for alkaloid‐enriched fractions from the leaves and inflorescence of P. juliflora revealed a 14 mm zone of inhibition, with the lowest MIC value being 30 mg/mL. Untargeted metabolomics analysis of alkaloid‐rich fractions (ARF) from four different tissues of P. juliflora, subjected to LC–MS for alkaloid identification, detected a total of 1489 peaks in positive mode and 240 peaks in negative mode. The highest peaks were detected in the leaves, where 47 metabolites and 9 alkaloids were identified. Ellipticine and ormosanine were found in relatively high concentrations across all four tissues, as indicated by their peak areas. The inflorescence had significantly high concentrations of sparteine, solanidine‐I and puberanidine compared with other parts. Additionally, acetylsolanine was more abundant in the inflorescence, while solasodine‐I was more prevalent in the leaves. A substantial amount of strictosidine was also found in the inflorescence. [ABSTRACT FROM AUTHOR]

Bacterial blight, incited by Xanthomonas citri pv. malvacearum (Xcm), is historically one of the most devastating diseases of cotton globally. In India, the initial documentation of the disease dates back to 1918 and it assumed a great magnitude after 1947, primarily triggered by cultivation of tetraploid cotton, as the earlier cultivated indigenous diploid cotton was naturally resistant to the pathogen, and became widespread during the 1970s. Among 20 races of bacterial blight pathogen documented at global level, Race 18 is the most virulent one and prominent in India. The pathogen inflicts damage at all crop stages, beginning with seedlings. The disease caused regular yield losses of 30%–35% in India and had become a formidable adversary to cotton cultivation in the country; however, over the years its appearance diminished. Much larger gains were apparently achieved when disease was managed with a combination of seed treatment, foliar sprays and bio‐agents. Furthermore, extensive breeding programmes led to development of resistant cultivars, which proved instrumental in managing the disease. The disease exhibited a sharp decline from the beginning of the 21st century and is now no longer a chronic problem in India. This comprehensive review attempts to provide insight into the dynamic nature of bacterial blight threatening cotton cultivation in India during the last century and the underpinning multifaceted research efforts that paved the way for countering the disease. An attempt is made to discuss the qualitative and quantitative studies on genetics of bacterial blight for facilitating the breeding programmes. [ABSTRACT FROM AUTHOR]

Rice production is drastically affected by biotic stresses, namely, bacterial leaf blight (BB), blast (BL) and brown planthopper (BPH). As marker-assisted selection for uniplex gene screening in breeding population is often tedious, time-consuming and expensive, multiplex PCR is practically a reasonable choice for the testing of genes in the pyramided lines as it offers significant time- and cost-saving advantages. Therefore, a cost-effective multiplex PCR-based screening for simultaneous detection of three BB (Xa21, xa13, and Xa4), two BL (Pi1and Pi54) and two BPH resistance genes (Bph20 and Bph21) has been developed. This multiplex system can detect different combinations of BB, BL and BPH resistance. In addition to this most cost-effective method, a five-gene (Xa21, xa13, Pi54, Bph20 and Bph21) multiplex assay in a single PCR tube for three biotic stresses, BB, BL and BPH, has been developed. These standardized multiplex assays have been incorporated into our breeding programs for accelerated results. These assays have displayed no deviation and are in perfect correlation with the individual marker screenings. As one of the most efficient and cost-saving technologies, this technology will have a great impact in the seed industry. [ABSTRACT FROM AUTHOR]

Sugars are caloric carbohydrate compound found in nature, such as fruits and vegetables, and are required by all organisms. During the phloem loading process, SWEET efflux sucrose from phloem parenchyma cells and then transports it to the sieve element-companion cell complex (SE/CC) via active proton-coupled sucrose transporters (SUTs). There are 21 SWEETs identified in rice that play important roles in sugar efflux, signal transduction, plant growth and development, and biotic and abiotic stress tolerance. TALE proteins are pathogen-produced effectors that interact with host susceptibility genes and induce OsSWEET proteins. In this study, genetic variations in the promoter region of OsSWEET11, OsSWEET13 and OsSWEET14 are examined in 20 genotypes grown in India. Further sequence analysis of three genotypes having extreme response (resistance and susceptibility) to bacterial blight revealed that the promoter of the resistant genotype Pusa basmati 1692 is more closely clustered with the xa13, xa25 resistance genes than compared to susceptible genotype Pusa basmati 1. Relative gene expression studies showed that upon Xoo inoculation, the fold expression of clade III OsSWEET genes, namely OsSWEET11, OsSWEET13, OsSWEET14 and OsSWEET15 increases in cultivars IR24, Pusa Basmati1 and Improved Pusa Basmati1. Intriguingly, after Xoo challenge inoculation, OsSWEET15 expression was found to be increased along with other major OsSWEET genes, implying that it could be a novel target for a bacterial blight pathogen. [ABSTRACT FROM AUTHOR]

Xanthomonas species infect many important crops and cause huge yield loss. These pathogens deliver transcription activator-like (TAL) effectors into the cytoplasm of plant cells. TAL effectors move to host nuclei, directly bind to the promoters of host susceptible genes, and activate their transcription. However, the molecular mechanisms by which TAL effectors induce host transcription remain unclear. We herein demonstrated that TAL effectors interacted with the SIMILAR TO RCD ONE (SRO) family proteins OsSRO1a and OsSRO1b in nuclei. A transactivation assay using rice protoplasts indicated that OsSRO1a and OsSRO1b enhanced the activation of the OsSWEET14 promoter by the TAL effector AvrXa7. The AvrXa7-mediated expression of OsSWEET14 was significantly reduced in ossro1a mutants. However, the overexpression of OsSRO1a increased disease resistance by up-regulating the expression of defense-related genes, such as WRKY62 and PBZ1. This was attributed to OsSRO1a and OsSRO1b also enhancing the transcriptional activity of WRKY45, a direct regulator of WRKY62 expression. Therefore, OsSRO1a and OsSRO1b appear to positively contribute to transcription mediated by bacterial TAL effectors and rice transcription factors. [ABSTRACT FROM AUTHOR]

• The bacterial blight disease caused by Xanthomonas citri pv. punicae (Xcp) poses a severe menace to pomegranate orchards. • Newly identified 126 expressed sequence tags from differential gene studies of resistant and highly susceptible genotypes associated with bacterial blight disease in pomegranate were deposited in the NCBI gen bank. • ROS changes were assessed during the course of pathogen infection and defence mechanisms were ascertained in comparison with gene expression studies. • The extent of damage due to disease was also assessed through histo-pathological studies. • Candidate genes associated with bacterial blight resistance in pomegranate were identified and qPCR validation of defence-related genes also confirmed the resistant reaction. The bacterial blight disease caused by Xanthomonas citri pv. punicae (Xcp) poses a severe menace to pomegranate orchards. The control of disease incurs huge expenditures, increasing the cost of cultivation. Hence, developing resistant varieties is an alternative measure for ecological sustainability and is the need of the hour. In this study, Suppression Subtractive Hybridization (SSH) was employed to identify candidate genes associated with bacterial blight resistance in pomegranate. A comparison was made between two genotypes, IC318734 (resistant-R) and Ruby (highly susceptible-HS), for differential gene elucidation and expression against Xcp. Through SSH, a panel of bacterial blight-resistant candidate genes was identified, including MLP-like protein 423, transcription factor MYB114-like, E3 ubiquitin-protein ligase ARI1, protein trichome birefringence-like 34, and serine/threonine-protein kinase. These genes play vital roles in energy and metabolism, transcription, signal transduction, intracellular traffic signaling, protein synthesis, defence, and stress responses. Validation through qRT-PCR revealed higher expression levels of these candidate genes in the R genotype compared to the HS one. Additionally, the levels of Reactive Oxygen Species (ROS) and Malondialdehyde (MDA) in both genotypes aligned with the differential gene expression data. Notably, the study also highlighted the augmented production of 12-oxophytodienoate reductase, associated with ROS generation, in the resistant genotypes. A sustained release of ROS triggered defence responses in the R genotype. Thus, these findings unravel defence mechanisms underlying bacterial blight resistance in pomegranate and provide potential targets for future crop improvement programmes. [ABSTRACT FROM AUTHOR]

Summary: The clade III subfamily of OsSWEETs includes transmembrane proteins necessary for susceptibility to bacterial blight (BB). These genes are targeted by the specific transcription activator‐like effector (TALE) of Xanthomonas oryzae pv. oryzae and mediate sucrose efflux for bacterial proliferation. However, the mechanism through which OsSWEETs regulate rice immunity has not been fully elucidated. Here, we demonstrated that the cytosolic carboxyl terminus of OsSWEET11a/Xa13 is required for complementing susceptibility to PXO99 in IRBB13 (xa13/xa13). Interestingly, the C‐terminus of ZmXa13, the maize homologue of OsSWEET11a/Xa13, could perfectly substitute for the C‐terminus of OsSWEET11a/Xa13. Furthermore, OsSWEET11a/Xa13 interacted with the high‐mobility group B1 (OsHMGB1) protein and the small heat shock‐like protein OsHsp20L through the same regions in the C‐terminus. Consistent with the physical interactions, knockdown or knockout of either OsHMGB1 or OsHsp20L caused an enhanced PXO99‐resistant phenotype similar to that of OsSWEET11a/OsXa13. Surprisingly, the plants in which OsHMGB1 or OsHsp20L was repressed developed increased resistance to PXO86, PXO61 and YN24, which carry TALEs targeting OsSWEET14/Xa41 or OsSWEET11a/Xa13. Additionally, OsHsp20L can interact with all six members of clade III OsSWEETs, whereas OsHMGB1 can interact with five other members in addition to OsSWEET12. Overall, we revealed that OsHMGB1 and OsHsp20L mediate conserved BB susceptibility by interacting with clade III OsSWEETs, which are candidates for breeding broad‐spectrum disease‐resistant rice. [ABSTRACT FROM AUTHOR]

To provide a scientific basis for controlling mulberry bacterial blight in Bazhong, Sichuan, China (BSC), this study aimed to isolate and purify pathogenic bacteria from diseased branches of mulberry trees in the region and to clarify their taxonomic status using morphological observation, physiological and biochemical detection, molecular-level identification, and the construction of a phylogenetic tree. A total of 218 bacterial strains were isolated from samples of diseased mulberry branches. Of these, 7 strains were identified as pathogenic bacteria based on pathogenicity tests conducted in accordance with Koch's postulates. Preliminary findings from the analysis of the 16S rRNA sequence indicated that the 7 pathogenic bacteria are members of Klebsiella spp. Morphological observation revealed that the pathogenic bacteria were oval-shaped and had capsules but no spores. They could secrete pectinase, cellulase, and protease and were able to utilize D-glucose, D-mannose, D-maltose, and D-Cellobiose. The 7 strains of pathogenic bacteria exhibited the highest homology with Klebsiella oxytoca. This study identifies Klebsiella oxytoca as the causative agent of mulberry bacterial blight in BSC, laying the foundation for the prevention and control of this pathogen and further investigation into its pathogenic mechanism. Supplementary Material Supplementary Material File [ABSTRACT FROM AUTHOR]

The bacterial blight of wheat is an important global disease causing a significant decline in crop yield. Nanotechnology offers a potential solution for managing plant diseases. Therefore, this research aimed to investigate the effectiveness of silver nanoparticles (AgNPs) in controlling bacterial blight in 27 locally grown wheat cultivars. The study examined the impact of AgNPs at three distinct time points: 1, 3, and 5 days after the onset of the disease. Biochemical assay revealed that one day after applying the disease stress, the Inia cultivar had the highest amount of soluble protein (55.60 μg.g−1FW) content in the treatment without AgNPs. The Azadi cultivar, without AgNPs treatment, had the lowest amount of soluble protein content (15.71 μg.g−1FW). The Tabasi cultivar had the highest activity of the superoxide dismutase (SOD) (61.62 mM.g−1FW) with the combination treatment of AgNPs. On the other hand, the Karchia cultivar had the lowest SOD activity (0.6 mM.g−1FW) in the treatment of disease without AgNPs. Furthermore, three days after the application of stress, the Mahdavi cultivar had the highest amount of soluble protein content (54.16 μg.g−1FW) in the treatment of disease without AgNPs. The Niknejad cultivar had the highest activity of the SOD (74.15 mM.g−1FW) with the combined treatment of the disease without AgNPs. The Kavir cultivar had the lowest SOD activity (1.95 mM.g−1FW) and the lowest peroxidase (POX) activity (0.241 mM g−1FW min−1) in the treatment of the disease with AgNPs. Five days after exposure to stress, the Mahooti cultivar had the highest SOD activity (88.12 mM.g−1FW) with the combined treatment of the disease with AgNPs, and the Karchia cultivar had the lowest SOD activity (2.39 mM.g−1FW) in the treatment of the disease with AgNPs. Further, the results indicated that exposure to AgNPs could improve the antioxidant properties of wheat seeds in blight-infected and disease-free conditions in some cultivars. [ABSTRACT FROM AUTHOR]

The article presents a study which evaluated and screened different doses for the management of bacterial blight, false smut and blast diseases of paddy. Topics discussed include assessment of false smut disease on paddy crop, bio-efficacy of cuprous oxide 86.2 percent WG against bacterial blight disease of paddy, and grain yields.

Lead toxicity and bacterial blight disease caused by Pseudomonas savastanoi pv. glycinea have destructive impacts on soybean growth and productivity. Plant growth-promoting rhizobacteria have been used as an eco-friendly approach for augmenting crop growth and stress resistance. The current study investigated the efficacy of Serratia liquefaciens ZM6 strain in enhancing soybean resistance to lead (Pb) stress and bacterial blight. Two pot experiments were performed. In the first pot experiment, soybean plants were inoculated with S. liquefaciens ZM6 and grown under variable Pb stress levels (0, 200 and 400 µM of Pb(NO3)2). In the second experiment, S. liquefaciens-inoculated soybean plants were infected with P. savastanoi pv. glycinea, and disease severity was assessed two weeks post infection. The results revealed that S. liquefaciens strain resisted Pb stress up to 400 µM Pb(NO3)2 and exhibited the highest levels of solubilized phosphate, solubilized zinc, siderophore, indole acetic acid, exopolysaccharide, trehalose and antioxidant enzymes at 400 µM Pb compared to the other treatments. Moreover, Pb stress (200 and 400 µM) significantly decreased the growth, yield, nutrient uptake, gas exchange, and contents of chlorophyll, soluble proteins, sugars, and phenolics of soybean plants. Pb stress also induced the levels of proline, glycine betaine, Pb, oxidative stress markers, antioxidant enzymes, ascorbate, glutathione and expression of stress-responsive genes (CAT, APX, POD, Fe-SOD, CHS7, CHI1A, PAL, IFS2, P5CS and WRKY54) in soybean plants. On the other hand, S. liquefaciens application markedly boosted the growth, yield and levels of nutrients, gas-exchange, chlorophyll, osmolytes, antioxidant enzymes and expression of stress-tolerant genes of Pb-stressed soybean plants. The bacterial inoculation significantly diminished oxidative stress indicators and Pb content in stressed plants. Inoculation of soybean plants with S. liquefaciens also caused significant reductions in blight disease symptoms in P. savastanoi pv. glycinea-infected plants, indicating the efficiency of this strain in controlling harmful blight disease. Overall, this study demonstrated S. liquefaciens ZM6 effectiveness in enhancing soybean resistance to Pb stress and bacterial blight.

Oryza sativa L. ssp. indica (RD47 cultivar) is a major commercial rice variety known for its highly stable yields. However, it is highly susceptible to bacterial blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo). While previous research has focused on improving rice cultivars through breeding programs, no reports involved the interaction between Xoo infection and gene expression. This study aimed to analyze the relationship between bacterial blight disease and gene expression, focusing on two resistance genes (Xa21 and XIK1) and one susceptible gene (OsSWEET14). Gene expression analysis revealed that the Xa21 gene conferred effective resistance against bacterial blight Xoo16PK002 infection, providing high and moderate resistance to bacterial blight symptoms in two rice varieties carrying the Xa21 gene, IRBB21 and the near–isogenic RD47–Xa21 BC4F4, respectively. Additionally, the Xa21 gene directly induced XIK1 expression in both resistance rice cultivars. Moreover, one susceptible gene, OsSWEET14, was consistently up–regulated in only the bacterial blight–susceptible indica rice cultivar RD47. Therefore, the up–regulation of resistance genes and the suppression of susceptible genes contributed to the improvement of bacterial blight disease in the RD47 cultivar. Xa21 emerged as a criti‐ cally important gene in directly inducing mechanisms against Xoo, thereby promoting the reduction of bacterial blight disease.

Diverse bacterial and fungal pathogens attack plants, causing biotic stress and severe yield losses globally. These losses are expected to become more serious as climate change improves conditions for many pathogens. Therefore, identifying genes conferring broad-spectrum disease resistance and elucidating their underlying mechanisms provides important resources for plant breeding. WRKY transcription factors affect plant growth and stress responses. However, the functions of many WRKY proteins remain to be elucidated. Here, we demonstrated the role of rice (Oryza sativa) WRKY group III transcription factor OsWRKY65 in immunity. OsWRKY65 localized to the nucleus and acted as transcriptional repressor. Genetic and molecular functional analyses showed that OsWRKY65 increases resistance to the fungal pathogen Fusarium fujikuroi through downregulation of GA signaling and upregulation of JA signaling. Moreover, OsWRKY65 modulated the expression of the key genes that confer susceptibility or resistance to Xanthomonas oryzae pv. oryzae to enhance immunity against the pathogen. In particular, OsWRKY65 directly bound to the promoter region of OsSWEET13 and repressed its expression. Taken together, our findings demonstrate that the OsWRKY65 enhances resistance to fungal and bacterial pathogens in rice.

Cluster bean (Cyamopsis tetragonoloba L. Taub.) (2n=14) is an indigenous, self-pollinated, drought tolerant legume crop. This crop has recently gained the status of industrial crop due to the high galactomannan content in the endosperm of its seed. This crop is vulnerable to bacterial leaf blight as one of the most destructive diseases of cluster bean caused by Xanthomonas axonopodis pv. cyamopsidis and confines cluster bean productivity in all growing regions. Biological control is an ecological-friendly approach to suppress the growth of phytopathogens. In this study, four bioagents viz. Bacillus subtilis, Providencia sp., Trichoderma viride and Trichoderma harzianum were evaluated against Xanthomonas axonopodis pv. cyamopsidis in vitro condition. Providencia sp. showed maximum antibacterial activity with 14.12 per cent zone inhibition followed by Bacillus subtilis (12.13%). The fungal antagonists viz. Trichoderma viride (7.11%) and Trichoderma harzianum (5.95%), were found least effective against the tested pathogen. Providencia sp.@ 25 per cent w/v reduce disease incidence of 50 per cent under screen house conditions followed by Bacillus subtilis (35.71%). Among the treatments, the lowest disease reduction and highest per cent disease incidence was observed in treatment with Trichoderma harzianum (7.14). Therefore, bioagents can be used as a sustainable tool for management of plant diseases towards sustainable agriculture [ABSTRACT FROM AUTHOR]

Conventional breeding approaches often rely on bi-parental crosses, in which analysis occurs only on two alleles, and genetic recombination in such a population is insufficient, limiting genetic diversity. Multi-parent advanced generation inter-cross (MAGIC) populations display large sets of recombinant inbred lines (RILs) that exhibit a genetic mosaic of multiple founder parents. MAGIC populations result in a broader genetic base that has emerged as a powerful tool for genetic analysis and breeding for disease resistance in rice. This study developed the MAGIC population by intermating eight diverse founder parents. Conducting the molecular survey sought to analyze the genes resistant to bacterial blight (BB) and brown planthopper (BPH). The research used primers specific for Xa21, xa13, Xa4, and Bph1 in the polymerase chain reaction (PCR). The survey identified combinations of three genes: (Xa4+xa13+Xa21) in BR52 and (Xa4+xa13+Bph1) in BR43, BR44, BR48, and BR58. Two-gene combination (xa13 and Xa4) materialized in BR53, BR54, BR60, BR73, BR85, and BR86, while identifying a combination of xa13 and Bph1 in BR11, BR41, and BR99. Xa4 was present in 14, xa13 in six, and Bph1 in three lines. Screening the population against Xanthomonas oryzae validated the presence of BB-resistant genes. The consistent finding is that the RILs with a combination of two or more genes express a high level of resistance compared with the RILs with a single gene. The RILs with Xa4 and xa13 expressed more resistance than the lines with xa13 and Bph1. Employing the MAGIC populations approach remains to be effective for gene pyramiding. [ABSTRACT FROM AUTHOR]

Bacterial blight (BB) caused by Xanthomonas citri pv. malvacearum (Xcm), poses a significant threat to Upland cotton (Gossypium hirsutum L.) production worldwide, and Xcm race 18 is the most virulent and widespread and can cause serious yield loss. Understanding the genetic basis of resistance in diploid Asiatic cotton (G. arboreum) and successfully transferring the resistance to tetraploid Upland cotton are crucial for developing resistant cotton cultivars. This study aimed to identify chromosomal regions for BB resistance through a genome-wide association study (GWAS) using 245 G. arboreum accessions evaluated in two replicated greenhouse tests and to evaluate an introgression BC2F7 population derived from a tri-species hybrid (G. arboreum/G. aridum/G. hirsutum). In response to Xcm race 18 infections after artificial inoculation, 80% of the accessions exhibited a high level of resistance, including 151 accessions showing immunity with no visible foliar water-soaked lesions. A GWAS based on 7009 polymorphic SNP markers detected 9 major BB resistance QTLs on chromosomes A01, A02, A05, A06, A10, A12 and A13 in the Asiatic cotton. The tri-species introgression population showed segregation in BB resistance with significantly lower disease incidence of BB than the susceptible check Acala 1517-18 GLS (30.2 vs. 100%), suggesting that the resistance in the diploid species has been successfully transferred into Upland cotton. The identification of Xcm race 18 resistant diploid Asiatic cotton germplasm and specific chromosomal regions and candidate genes delineated by SNPs for resistance for the first time provides strong evidence that the Asiatic cotton is a new genetic source of resistance to Xcm race 18. The results will facilitate further genetic and genomic studies toward the eventual identification of resistance genes in Asiatic cotton and their transfer into tetraploid cotton through marker-assisted selection. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) yield, quality and resistance to various biotic and abiotic stresses are the major barriers of rice production worldwide. Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae, is a major cause of reduced yield in rice. In the present study, a set of 43 advance breeding lines along with 6 check varieties was evaluated for yield attributes, milling quality traits and BB resistance. The results indicated a significant variation for various morpho-physiological and milling traits. Disease screening was carried out in field at maximum tillering stage under artificial inoculation conditions. Based on pathogenicity test, 36 genotypes showed resistance to all the ten BB pathotypes prevalent in northern India (Punjab). Further, these lines were characterized for known BB resistance gene(s); Xa4, xa5, xa13 and Xa21 using linked molecular markers and molecular analysis showed a wide range of gene combinations and indicated the presence of single (6), two (23), and three (13) gene combinations while one line (PAU 5285-23-1-2) showed none of the known gene tested. The genotypes PAU 7261-19-1, PAU 6998-110-3-1, PAU 6516-11-1-2-1-1, PAU 6554-1-1-1-2-3, PAU 6970-18-1-3, PAU 6707-33-6-1-1-1-3 had significantly and consistently high yield with early maturity, semi dwarf, good tillering along with desirable quality traits. Moreover, these are resistant to all ten pathotypes of BB presently prevalent in the Punjab state. Therefore, it is recommended that these can be utilized further to identify and develop improved varieties with high yield, early to mid-maturity, desirable milling quality and BB resistance. [ABSTRACT FROM AUTHOR]

Background: Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases of rice leading to huge yield losses in Southeast Asia. The recessive resistance gene xa-45(t) from Oryza glaberrima IRGC102600B, mapped on rice chromosome 8, spans 80 Kb with 9 candidate genes on Nipponbare reference genome IRGSP-1.0. The xa-45(t) gene provides durable resistance against all the ten Xanthomonas pathotypes of Northern India, thus aiding in the expansion of recessive bacterial blight resistance gene pool. Punjab Rice PR127, carrying xa-45(t), was released for wider use in breeding programs. This study aims to precisely locate the target gene among the 9 candidates conferring resistance to bacterial blight disease. Methods and results: Sanger sequencing of all nine candidate genes revealed seven SNPs and an Indel between the susceptible parent Pusa 44 and the resistant introgression line IL274. The genotyping with polymorphic markers identified three recombinant breakpoints for LOC_Os08g42370, and LOC_Os08g42400, 15 recombinants for LOC_Os08g423420 and 26 for LOC_Os08g42440 out of 190 individuals. Relative expression analysis across six time intervals (0, 8, 24, 48, 72, and 96 h) after bacterial blight infection showed over expression of LOC_Os08g42410-specific transcripts in IL274 compared to Pusa 44, with a significant 4.46-fold increase observed at 72 h post-inoculation. Conclusions: The Indel marker at the locus LOC_Os08g42410 was found co-segregating with the phenotype, suggesting its candidacy towards xa-45(t). The transcript abundance assay provides strong evidence for the involvement of LOC_Os08g42410 in the resistance conferred by the bacterial blight gene xa-45(t). [ABSTRACT FROM AUTHOR]

Background: Rice blast and bacterial leaf blight (BLB) are the most limiting factors for rice production in the world which cause yield losses typically ranging from 20 to 30% and can be as high as 50% in some areas of Asia especially India under severe infection conditions. Methods and results: An improved line of Tellahamsa, TH-625-491 having two BLB resistance genes (xa13 and Xa21) and two blast resistance genes (Pi54 and Pi1) with 95% Tellahamsa genome was used in the present study. TH-625-491 was validated for all four target genes and was used for backcrossing with Tellahamsa. Seventeen IBC1F1 plants heterozygous for all four target genes, 19 IBC1F2 plants homozygous for four, three and two gene combinations and 19 IBC1F2:3 plants also homozygous for four, three and two gene combinations were observed. Among seventeen IBC1F1 plants, IBC1F1-62 plant recorded highest recurrent parent genome (97.5%) covering 75 polymorphic markers. Out of the total of 920 IBC1F2 plants screened, 19 homozygous plants were homozygous for four, three and two target genes along with bacterial blight resistance. Background analysis was done in all 19 homozygous IBC1F2 plants possessing BLB resistance (possessing xa13, Xa21, Pi54 and Pi1 in different combinations) with five parental polymorphic SSR markers. IBC1F2-62-515 recovered 98.5% recurrent parent genome. The four, three and two gene pyramided lines of Tellahamsa exhibited varying resistance to blast. Conclusions: Results show that there might be presence of antagonistic effect between bacterial blight and blast resistance genes since the lines with Pi54 and Pi1 combination are showing better resistance than the combinations with both bacterial blight and blast resistance genes. [ABSTRACT FROM AUTHOR]

Rice straw presents challenges as livestock feed due to its low digestibility and the presence of chemical residues. One potential solution is to focus on breeding brittle varieties that possess disease-resistance traits. In this study, AZ1803, a brittle mutant line isolated from the IR64 mutant pool, was chosen for gene identification and breeding. The AZ1803 mutant was crossed to the TNG67 variety to generate a mapping population and to the CS11 variety for fine mapping and breeding. The gene was mapped on chr. 10 between RM467 and RM171 SSR markers and was narrowed down to RM271 and RM5392 with 600 kb proximately interval. The AZ1803 and IR64 sequencing results revealed a substitution mutant in the Exon 9th of the OsCesA7 gene, resulting in an amino acid mutation at the end of the transmembrane domain 5th of the CESA7, responsible for cellulose synthesis for the secondary cell wall. The cellulose content of AZ1803 was reduced by 25% compared with the IR64. A new brittle and disease-resistant variety was bred by using developed markers in marker-assisted selection. In addition, bending tests and bacterial blight inoculation were applied. The bacterial lesion length of the bred variety is 64% lower than that of AZ1803. The rice straw of the new variety can be used for livestock feeding, which increases farmer income and reduces pesticide residues and air pollution from straw burning. [ABSTRACT FROM AUTHOR]

The basic leucine zipper (bZIP) is an important class of transcription factors in plants, playing a critical role in plant growth and development and responses to biotic and abiotic stress. Due to gene presence/absence variations, it is limited to identify bZIP genes based on the reference genome. Therefore, we performed the bZIP gene family analysis in the rice pan-genome. By employing a rice pan-genome, ninety-four OsbZIPs (72 core genes and 22 variable genes) were identified and divided into 11 groups in a phylogenetic tree. Based upon Ka/Ks values in 33 accessions, OsbZIPs were subjected to different selection pressures during domestication. The analysis of the effects of structural variations (SVs) on gene expression, gene structure, and conserved domains showed that SVs could significantly alter the expression levels of certain OsbZIPs, leading to gene truncation and the emergence of numerous atypical genes. Thirty-four differentially expressed OsbZIPs were identified by analyzing RNA-seq data of the Xanthomonas oryzae pv. oryzae (Xoo) infection susceptible (IR24) and resistant (IRBB67) lines under high temperature, and by counting the number of differentially expressed OsbZIPs in different subgroups. These OsbZIPs were found to respond to Xoo infection at an early stage and may not be involved in the mechanism of Xa4 and Xa7 resistance to Xoo. The multiple variation patterns of OsbZIP genes provide new insights into the OsbZIP genes in rice. These results provide new resources and offer new directions for functional studies of OsbZIPs. [ABSTRACT FROM AUTHOR]

Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is a widespread and destructive disease in rice production. Previously, we cloned an executor R gene, Xa7, which confers durable and broad-spectrum resistance to BB. Here, we further confirmed that the transcription activator-like effector (TALE) AvrXa7 in Xoo strains could directly bind to the effector-binding element (EBE) in the promoter of the Xa7 gene. Other executor R genes (Xa7, Xa10, Xa23, and Xa27) driven by the promoter of the Xa7 gene could be activated by AvrXa7 and trigger the hypersensitive response (HR) in tobacco leaves. When the expression of the Xa23 gene was driven by the Xa7 promoter, the transgenic rice plants displayed a similar resistance spectrum as the Xa7 gene, demonstrating that the disease resistance characteristics of executor R genes are mainly determined by their induction patterns. Xa7 gene is induced locally by Xoo in the infected leaves, and its induction not only inhibited the growth of incompatible strains but also enhanced the resistance of rice plants to compatible strains, which overcame the shortcomings of its race-specific resistance. Transcriptome analysis of the Xa7 gene constitutive expression in rice plants displayed that Xa7-mediated disease resistance was related to the biosynthesis of lignin and thus enhanced resistance to Xoo. Overall, our results provided novel insights and important resources for further clarifying the molecular mechanisms of the executor R genes. [ABSTRACT FROM AUTHOR]

Copyright of Harran Journal of Agricultural & Food Science is the property of Harran University, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant disease resistance (R) gene-mediated effector-triggered immunity (ETI) is usually associated with hypersensitive response (HR) and provides robust and race-specific disease resistance against pathogenic infection. The activation of ETI and HR in plants is strictly regulated, and improper activation will lead to cell death. Xa27 is an executor-type R gene in rice induced by the TAL effector AvrXa27 and confers disease resistance to Xanthomonas oryzae pv. oryzae (Xoo). Here we reported the characterization of a transgenic line with lesion mimic phenotype, designated as Spotted leaf and resistance 1 (Slr1), which was derived from rice transformation with a genomic subclone located 5,125 bp downstream of the Xa27 gene. Slr1 develops spontaneous lesions on its leaves caused by cell death and confers disease resistance to both Xoo and Xanthomonas oryzae pv. oryzicola. Further investigation revealed that the Slr1 phenotype resulted from the ectopic expression of an Xa27 paralog gene, designated as Xa27B, in the inserted DNA fragment at the Slr1 locus driven by a truncated CaMV35Sx2 promoter in reverse orientation. Disease evaluation of IRBB27, IR24, and Xa27B mutants with Xoo strains expressing dTALE-Xa27B confirmed that Xa27B is a functional executor-type R gene. The functional XA27B-GFP protein was localized to the endoplasmic reticulum and apoplast. The identification of Xa27B as a new functional executor-type R gene provides additional genetic resources for studying the mechanism of executor-type R protein-mediated ETI and developing enhanced and broad-spectrum disease resistance to Xoo through promoter engineering. [Graphic: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

India is the major producer of cluster bean (Cyamopsis tetragonoloba L. Taub.) contributing about 82 per cent of the total production of the world and bacterial leaf blight is one of its most destructive disease caused by Xanthomonas axonopodis pv. cyamopsidis. It causes yield loss of 50-70 per cent of cluster bean under severe conditions, if appropriate measures to combat the disease are not taken timely. The disease effects crop productivity in all growing regions of the world. In Haryana state, the bacterial blight has been recognized as most important limiting factor in reducing the yield. It is both seed borne and air borne in nature and affects all above ground parts of plant. Chemicals have played significant role in management of the disease but their use in excessive amount led to detrimental effect on the ecosystem such as residual toxicity, harmful effect on living beings and the whole environment, especially on the beneficial predators, parasites and microorganisms. Keeping this in view, the present investigation has been devised on disease management using various biorational components during 2020-2021 at Hisar. It was observed that Azadirachta indica was found most effective with 18.04 per cent growth inhibition followed by Zingiber officinale under in vitro conditions. Under screen house conditions, minimum per cent disease incidence (PDI) of 26.67 per cent was observed in treatment of Azadirachta indica @ 25 per cent w/v followed by treatments of Zingiber officinale @ 25 per cent w/v. [ABSTRACT FROM AUTHOR]

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight (BB), a globally devastating disease of rice (Oryza sativa) that is responsible for significant crop loss. Sugars and sugar metabolites are important for pathogen infection, providing energy and regulating events associated with defense responses; however, the mechanisms by which they regulate such events in BB are unclear. As an inevitable sugar metabolite, methylglyoxal (MG) is involved in plant growth and responses to various abiotic stresses, but the underlying mechanisms remain enigmatic. Whether and how MG functions in plant biotic stress responses is almost completely unknown. Here, we report that the Xoo strain PXO99 induces OsWRKY62.1 to repress transcription of OsGLY II genes by directly binding to their promoters, resulting in overaccumulation of MG. MG negatively regulates rice resistance against PXO99: osglyII2 mutants with higher MG levels are more susceptible to the pathogen, whereas OsGLYII2- overexpressing plants with lower MG content show greater resistance than the wild type. Overexpression of OsGLYII2 to prevent excessive MG accumulation confers broad-spectrum resistance against the biotrophic bacterial pathogens Xoo and Xanthomonas oryzae pv. oryzicola and the necrotrophic fungal pathogen Rhizoctonia solani , which causes rice sheath blight. Further evidence shows that MG reduces rice resistance against PXO99 through CONSTITUTIVE DISEASE RESISTANCE 1 (OsCDR1). MG modifies the Arg97 residue of OsCDR1 to inhibit its aspartic protease activity, which is essential for OsCDR1-enhanced immunity. Taken together, these findings illustrate how Xoo promotes infection by hijacking a sugar metabolite in the host plant. Sugars and sugar metabolites are important for plant–pathogen interactions. This study demonstrates that Xoo , which causes rice bacterial blight disease, upregulates OsWRKY62.1 expression to promote the accumulation of MG and that MG negatively regulates rice resistance by modifying and inhibiting OsCDR1 protease activity. The study reveals how bacterial pathogens promote their infection by manipulating the accumulation of a sugar metabolite in the host plant. [ABSTRACT FROM AUTHOR]

Key message: OsMKK1, a MAPK gene, positively regulates rice Xa21-mediated resistance response and also plays roles in normal growth and development process of rice. The mitogen-activated protein kinase (MAPK) cascade was highly conserved among eukaryotes, which played crucial roles in plant responses to pathogen infection. Bacterial blight is the most devastating bacterial disease. Xa21 confers broad-spectrum resistance to Xanthomonas oryzae pv. Oryzae (Xoo). This study identified that the transcription level of OsMKK1 was up-regulated in resistant response against Xoo, thus overexpression (OsMKK1-OX) and RNA interference (OsMKK1-RNAi) transgenic rice lines under the background of Xa21 was constructed. Compared with recipient control plants 4021, the OsMKK1-OX lines significantly enhanced disease resistance to Xoo, on the contrary, the resistance of OsMKK1-RNAi lines was weakened, demonstrated that OsMKK1 played a positive role in Xa21-mediated disease resistance pathway. A number of pathogenesis-related proteins, including PR1A, PR2 and PR10A showed enhanced expression in OsMKK1-OX lines, supported that these PR genes may be regulated by OsMKK1 to participate in the defense responses. In addition, the agronomic traits of OsMKK1 transgenic plants were affected. Overall, these results revealed the role of OsMKK1 in Xa21-mediated resistance against Xoo and in the normal growth and development process in rice. [ABSTRACT FROM AUTHOR]

Phospholipids are important components of biological membranes, participating in various biological processes, including plant development and responses to biotic and abiotic stresses. A previous study showed that mutation of the rice OsCDS5 (CDP‐DAG Synthase) gene alters lipid metabolism, causing enhanced abiotic stress responses, yellowing of leaves at the seedling stage and delayed plant development. Here, we observed that the Oscds5 mutant shows enhanced resistance to rice blast, bacterial blight and bacterial leaf streak. Mutation of OsCDS5 promotes production of reactive oxygen species and increases the expression level of multiple defence‐related genes. Transcriptomic analyses indicate that genes involved in responses to stress, biotic/abiotic stimuli and metabolic processes are highly upregulated and enriched in mutant Oscds5. Metabolomic analyses showed that differential metabolites were enriched in the lipid metabolic and tryptophan metabolic pathways. The decreased level of phosphatidylinositol and increased level of serotonin probably contribute to enhanced disease resistance of the Oscds5 mutant. Taken together, mutation of OsCDS5 enhances abiotic and biotic stress responses, and OsCDS5 may be a promising target for genetic engineering to enhance the resilience of rice to abiotic and biotic stresses simultaneously. [ABSTRACT FROM AUTHOR]

Aims: The objective of the study was to isolate bacteriophages and conduct a comprehensive analysis of their potential against Xanthomonas oryzae pv. oryzae (Xoo) strains in the Mekong Delta, Vietnam. Methodology and results: Twelve Xoo strains were isolated from rice fields located in the Mekong Delta, Vietnam. Among these strains, three strains Xoo L019, L020 and L024, showed the highest disease index of bacterial blight. Four phages specific to Xoo were isolated from soil, water and leaf samples, and their morphologies were determined. In a test against 12 Xoo strains, phage L541, MLA23 or W41 could infect 10 of the 12 Xoo strains, while phage LBH01 could infect 8 of the 12 Xoo strains. The stability of the phages to pH, organic solvents, UV-A and UV-B was also evaluated. Conclusion, significance and impact of study: The initial characterization of the phages indicates their potential as biocontrol agents against bacterial blight in rice. The study is one of the very first studies about Xoo phages in rice in Vietnam. [ABSTRACT FROM AUTHOR]

Xanthomonas oryzae pv. oryzae (Xoo) is a destructive pathogen that causes bacterial blight disease of rice worldwide. Xoo uses T3SS (type III secretion system) effectors to subvert rice innate immunity. However, the comprehensive knowledge of rice genes involved in T3SS effectors-mediated interaction remains unclear. In this study, the transcriptome profiles of rice infected with a virulent Xoo strain from North-eastern region of India relatives to its avirulent strain (that lacks functional T3SS) were analyzed at early (2-6 hpi) and late (16-24 hpi) hours of infection. Out of total 255 differentially expressed genes (DEGs), during early infection, 62 and 70 genes were upregulated and downregulated, respectively. At late infection, 70 and 53 genes were upregulated and downregulated, respectively. The transcriptomic data identified many differentially expressed resistant genes, transposons, transcription factors, serine/threonine protein kinase, cytochrome P450 and peroxidase genes that are involved in plant defense. Pathway analysis revealed that these DEGs are involved in hormone signaling, plant defense, cellular metabolism, growth and development processes. DEGs associated with plant defense were also validated through quantitative real-time PCR. Our study brings a comprehensive picture of the rice genes that are being differentially expressed during bacterial blight infection. Nevertheless, the DEG-associated pathways would provide sensible targets for developing resistance to bacterial blight.Supplementary informationThe online version contains supplementary material available at 10.1007/s13205-022-03193-4.

Identification of immunity-associated leucine-rich repeat receptor-like protein kinases (LRR-RLK) is critical to elucidate the LRR-RLK mediated mechanism of plant immunity. Here, we reported the map-based cloning of a novel rice SPOTTED-LEAF 41 (OsSPL41) encoding a putative LRR-RLK protein (OsLRR-RLK41/OsSPL41) that regulated disease responses to the bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). An 8-bp insertion at position 865 bp in a mutant spotted-leaf 41 (spl41) allele led to the formation of purple-brown lesions on leaves. Functional complementation by the wild type allele (OsSPL41) can rescue the mutant phenotype, and the complementary lines showed similar performance to wild type in a number of agronomic, physiological and molecular indices. OsSPL41 was constitutively expressed in all tissues tested, and OsSPL41 contains a typical transmembrane domain critical for its localization to the cell membrane. The mutant exhibited an enhanced level of resistance to Xoo in companion of markedly up-regulated expression of pathogenesis-related genes such as OsPR10a, OsPAL1 and OsNPR1, while the level of salicylic acid was significantly increased in spl41. In contrast, the over-expression lines exhibited a reduced level of H2O2 and were much susceptible to Xoo with down-regulated expression of pathogenesis-related genes. These results suggested that OsSPL41 might negatively regulate plant immunity through the salicylic acid signaling pathway in rice.

Abstract Upon Xanthomonas oryzae pv. oryzae (Xoo) infection of rice leaves, the invasion induces systematic expression changes for both the coding genes and the non-coding genes, allowing the plant to make corresponding responses. However, the roles of circular RNAs (circRNAs) in rice defending against Xoo remain largely unknown. To address this question, we conducted a whole-transcriptomic analysis to systematically screen the differentially expressed (DE) mRNAs and non-coding RNAs (ncRNAs) in rice responding to Xoo infection. Our results revealed a total of 4076 DE mRNAs, 89 DE long non-coding RNAs (lncRNAs), 82 DE microRNAs (miRNAs), and 14 DE circRNAs identified from Xoo-infected rice plants at 48 h post inoculation. Three circRNAs (ciR52, ciR298, and ciR133) were found to be able to form circular RNAs, and their expression was induced by Xoo infection. ciR133 was found to repress the expression of its parental gene OsARAB (putative arabinofuranosidase gene) during Xoo infection. Overexpression of ciR133 and mutation of OsARAB enhanced rice resistance against Xoo, without compromising main agronomic traits. Our data suggest that circRNAs are associated with rice response to Xoo infection, providing a potential strategy for breeding Xoo-resistant rice plants by manipulating ciR133 and OsARAB.

Gangavati sona (GS) is a high-yielding, fine-grain rice variety widely grown in the Tungabhadra command area in Karnataka, India; however, it is susceptible to bacterial blight (BB). Therefore, the present study was conducted to improve the GS variety for BB resistance. Three BB-resistant genes (xa5, xa13, and Xa21) were introgressed into the genetic background of susceptible cultivar GS through marker-assisted backcrossing (MABB) by using Improved samba Mahsuri (ISM), a popular, high-yielding, bacterial blight resistant rice variety as a donor parent. Foreground selection was carried out using gene-specific markers, viz., xa5FM (xa5), xa13prom (xa13), and pTA248 (Xa21), while background selection was carried out using well-distributed 64 polymorphic microsatellite markers. The true heterozygote F1 was used as the male parent for backcrossing with GS to obtain BC1F1. The process was repeated in BC1F1 generation, and a BC2F1 plant (IGS-5-11-5) possessing all three target genes along with maximum recurrent parent genome (RPG) recovery (86.7%) was selfed to obtain BC2F2s. At BC2F2, a single triple gene homozygote plant (IGS-5-11-5-33) with 92.6% RPG recovery was identified and advanced to BC2F5 by a pedigree method. At BC2F5, the seven best entries were selected, possessing all three resistance genes with high resistance levels against bacterial blight, yield level, and grain quality features equivalent to better than GS. The improved versions of GS will immensely benefit the farmers whose fields are endemic to BB. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)