Bacterial Blight Disease Research Articles

Effectiveness of Bacillus and Pseudomonas Strains in Biological Control of Common Bacterial Blight Disease in Common Bean (Phaseolus vulgaris L.)

Effectiveness of Bacillus and Pseudomonas Strains in Biological Control of Common Bacterial Blight Disease in Common Bean (Phaseolus vulgaris L.)

Phosphatidylcholine Transfer Protein OsPCTP Interacts with Ascorbate Peroxidase OsAPX8 to Regulate Bacterial Blight Resistance in Rice.

Rice phosphatidylcholine transfer protein (PCTP), which contains a steroidogenic acute regulatory protein-related lipid transfer (START) domain, responds to bacterial blight disease. Overexpression of OsPCTP quantitatively enhances resistance to pathogen in rice, whereas depletion of it has the opposite effect. Further analysis showed that OsPCTP physically interacts with OsAPX8, a ROS scavenging enzyme, and influences ascorbate peroxidase enzymatic activity in vivo. In addition, the expression of pathogenesis-related genes PR1a, PR1b and PR10 were significantly induced in OsPCTP-OE plants compared with that in wild-type plants ZH11. Taken together, these results suggested that OsPCTP mediates bacterial blight resistance in rice through regulating the ROS defense pathway.

Modeling climate-related global risk maps of rice bacterial blight caused by Xanthomonas oryzae (Ishiyama 1922) using geographical information system (GIS).

Rice is a critical staple crop that feeds more than half of the world's population. Still, its production confronts various biotic risks, notably the severe bacterial blight disease produced by Xanthomonas oryzae. Understanding the possible effects of climate change on the geographic distribution of this virus is critical to ensuring food security. This work used ecological niche modeling and the Maxent algorithm to create future risk maps for the range of X. oryzae under several climate change scenarios between 2050 and 2070. The model was trained using 93 occurrence records of X. oryzae and five critical bioclimatic variables. It has an excellent predictive performance, with an AUC of 0.889. The results show that X. oryzae's potential geographic range and habitat suitability are expected to increase significantly under low (RCP2.6) and high (RCP8.5) emission scenarios. Key climatic drivers allowing this development include increased yearly precipitation, precipitation during the wettest quarter, and the wettest quarter's mean temperature. These findings are consistent with broader research revealing that climate change is allowing many plant diseases and other dangerous microbes to spread across the globe. Integrating these spatial predictions with data on host susceptibility, agricultural practices, and socioeconomic vulnerabilities can help to improve targeted surveillance, preventative, and management methods for reducing the growing threat of bacterial blight to rice production. Proactive, multidisciplinary efforts to manage the changing disease dynamics caused by climate change will be critical to assuring global food security in the future decades.

Holliday junction resolvase RuvC targets biofilm eDNA and confers plant resistance to vascular pathogens.

A biofilm lifestyle is critical for bacterial pathogens to colonize and protect themselves from host immunity and antimicrobial chemicals in plants and animals. The formation and regulation mechanisms of phytobacterial biofilm are still obscure. Here we found that the protein Ralstonia solanacearum resistance to ultraviolet C (RuvC) is highly abundant in biofilm and positively regulates pathogenicity by controlling systemic movement in tomato xylem. RuvC protein accumulates at the later stage of biofilm development and specifically targets Holliday junction (HJ)-like structures to disrupt the biofilm extracellular DNA (eDNA) lattice, thus facilitating biofilm dispersal. Recombinant RuvC protein can resolve extracellular HJ to prevent bacterial biofilm formation. Heterologous expression of R. solanacearum or Xanthomonas oryzae pv. oryzae RuvC with plant secretion signal in tomato or rice confers resistance to bacterial wilt or bacterial blight disease, respectively. Plant chloroplast-localized HJ resolvase monokaryotic chloroplast 1 (MOC1), which shares structural similarity with bacterial RuvC, shows a strong inhibitory effect on bacterial biofilm formation. Relocalization of SlMOC1 to apoplast in tomato roots leads to increased resistance to bacterial wilt. Our novel finding reveals a critical pathogenesis mechanism of R. solanacearum and provides an efficient biotechnology strategy to improve plant resistance to bacterial vascular disease.

Pyramiding of multiple resistant genes of blast and bacterial blight diseases in the background of rice (Oryza sativa) mega variety BRRI dhan29

Blast and bacterial blight (BB) are the two major rice diseases in the world including Bangladesh. In this study, BB resistance genes (Xa21 and xa13) and blast resistance (Pi9 and Pb1) genes were pyramided into a mega variety, BRRI dhan29 through marker-assisted backcross breeding. IRBB58 was used as a BB-resistant donor and Pi9-US2, and Pb1-US2 were used as blast-resistant donors. Backcross was done between BRRI dhan29 and donor parents to develop BC3F1 population and then selfing was done to develop BC3F6 population. BC3F2 population was genotyped and phenotyped for segregation analysis and BC3F6 was evaluated for genotyping, phenotyping and morphological traits and yields. Chi-square analysis of BC3F2 data revealed that blast and BB resistance followed the single gene mendelian fashion (1:2:1 and 3:1). Two to four gene combinations were found in the advanced lines of the BC3F6 population. The yield of the advanced lines ranged from 6.42 (t ha-1) to 9.5 (t ha-1) and they showed resistant against blast and BB with mean disease scores ranging from 0.67 to 2.33 and 0.33 to 2.33, respectively. Finally, eight lines having four genes (xa13, Xa21, Pi9 and Pb1) were selected for multilocational (five locations) trials for yield performance and disease reaction. Mean yield data of eight advanced lines of all locations were varied from 6.48±0.15 to 8.38±0.11 t ha-1 and all the lines showed resistant reactions against blast (score 0.53 to 1) and BB (score 0.6 to 0.87) disease. The highest yield was found in BR (Path) 13800-BC3-224-12 (G28, 8.38±0.11 t ha-1) followed by BR (Path) 13800-BC3-134-252 (G26, 8.28±0.08 t ha-1) and BR (Path) 13800-BC3-136-115 (G12, 8.24±0.07 t ha-1). Pyramided advanced lines of this study could be released as BB and blast-resistant varieties or could be utilized as donor parents in resistant breeding.

Multi-functional PGPR Serratia liquefaciens confers enhanced resistance to lead stress and bacterial blight in soybean (Glycine max L.)

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 400µM 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 400µM Pb(NO3)2 and exhibited the highest levels of solubilized phosphate, solubilized zinc, siderophore, indole acetic acid, exopolysaccharide, trehalose and antioxidant enzymes at 400µM Pb compared to the other treatments. Moreover, Pb stress (200 and 400µM) 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.

Development and Validation of an SNP Marker for Identifying Xanthomonas oryzae pv. oryzae Thai Isolates That Break xa5-Mediated Bacterial Blight Resistance in Rice.

Xanthomonas oryzae pv. oryzae (Xoo) is a pathogenic bacterium responsible for bacterial blight (BB) disease in rice, primarily mediated by the interaction between the plant and pathogen. The virulence mechanism involves the activation of the Sugars Will Eventually be Exported Transporter (SWEET) gene family in rice by transcription activator-like effectors derived from Xoo. The BB resistance gene xa5 has been identified as one of the most effective genes against Thai Xoo isolates, but xa5-mediated resistance-breaking Xoo strains have emerged. This study aimed to develop a single nucleotide polymorphism (SNP) marker for precise identification of xa5-mediated resistance-breaking Xoo. Comparative genomics of Thai Xoo isolates Xoo16PK001 and Xoo16PK002, which were incompatible and compatible with rice variety IRBB5 carrying xa5, respectively, identified eight SNP positions for the development of an SNP marker. The SNP marker XooE6 yields a specific 1,143 bp PCR product unique to Xoo16PK002. Screening 61 Thai isolates using XooE6 identified two positives: Xoo20PL010 and Xoo20UT002. Inoculation tests on rice varieties IRBB5 and IRBB13 demonstrated compatibility with IRBB5 and incompatibility with IRBB13, which bears Xa5 and xa13. Xoo16PK001 (XooE6-negative) showed different virulence. Inoculation on IRBB21 harboring Xa5, Xa13, and Xa21 resulted in partial resistance to both XooE6-positive and -negative strains. XooE6-positive strains up-regulated SWEET11 and suppressed SWEET14 in IRBB5, while Xoo16PK001 slightly induced SWEET11 but activated SWEET14 in IRBB13. This highlights the potential of XooE6 to identify xa5-mediated resistance-breaking Xoo strains and elucidate their pathogenic mechanisms through the upregulation of SWEET11.

A Novel SPOTTED LEAF1-1 (SPL11-1) Gene Confers Resistance to Rice Blast and Bacterial Leaf Blight Diseases in Rice (Oryza sativa L.)

Programmed cell death (PCD) plays critical roles in plant immunity but must be regulated to prevent excessive damage. In this study, a novel spotted leaf (spl11-1) mutant was identified from an ethyl methane sulfonate (EMS) population. The SPL11-1 gene was genetically mapped to chromosome 12 between the Indel12-37 and Indel12-39 molecular markers, which harbor a genomic region of 27 kb. Annotation of the SPL11-1 genomic region revealed the presence of two candidate genes. Through gene prediction and cDNA sequencing, it was confirmed that the target gene in the spl11-1 mutant is allelic to the rice SPOTTED LEAF (SPL11), hereafter referred to as spl11-1. Sequence analysis of SPL11 revealed a single bp deletion (T) between the spl11-1 mutant and the ‘Shuangkang77009’ wild type. Moreover, protein structure analysis showed that the structural differences between the SPL11-1 and SPL11 proteins might lead to a change in the function of the SPL11 protein. Compared to the ‘Shuangkang77009’ wild type, the spl11-1 mutant showed more disease resistance. The agronomical evaluation showed that the spl11-1 mutant showed more adverse traits. Through further mutagenesis treatment, we obtained the spl11-2 mutant allelic to spl11-1, which has excellent agronomic traits and more improvement and may have certain breeding prospects in future breeding for disease resistance.

Effect of radiation on the incidence and severity of bacterial blight disease induced by Xanthomonas axonopodis pv. Vignicola on some varieties of cowpea (Vigna unguiculata L. Walp)

Effect of radiation on the incidence and severity of bacterial blight disease induced by Xanthomonas axonopodis pv. Vignicola on some varieties of cowpea (Vigna unguiculata L. Walp)

Harnessing phages as biocontrol agents against common bacterial blight diseases in plants

Bacterial blight diseases in plants are caused by various bacterial pathogens such as Dickeya, Pectobacterium, Xanthomonas, and others. They infect a wide range of crops including potatoes, tomatoes, apples, and citrus. The impact of these diseases includes reduced crop yields, lower quality produce, and economic losses for farmers. Traditional control methods like antibiotics and copper-based compounds are becoming less effective due to the development of resistance and environmental concerns. As a result, there is growing interest in alternative strategies such as biocontrol agents (BCAs), particularly bacteriophages. Bacteriophages are viruses that infect bacteria, they offer a promising solution to agricultural disease management. Their specificity and ability to target pathogenic bacteria make them an environmentally friendly alternative to chemical interventions. By optimizing phage formulations and application protocols, bacteriophages have the potential to contribute to healthier crops, increased yields, and a more sustainable agricultural system.

Closing the information gap between the field and scientific literature for improved disease management- with a focus on rice and bacterial blight.

A path to sustainably reduce world hunger, food insecurity, and malnutrition is to close the crop yield gap, particularly, losses due to pathogens. Breeding resistant crops is key to achieving this goal, an effort requiring collaboration among stakeholders, scientists, breeders, farmers and policymakers. During a disease outbreak, epidemiologists survey the occurrence of a disease after which pathologists investigate mechanisms to stop an infection. Policymakers then implement strategies with farmers and breeders to overcome the outbreak. Information flow from the field to the lab and back to the field involves several processing hubs that require different information inputs. Failure to communicate the necessary information results in the transfer of meaningless data. Here, we discuss gaps in information acquisition and transfer between the field and laboratory. Using rice bacterial blight disease as an example, we discuss pathogen biology and disease resistance to point out the importance of reporting pathogen strains that caused an outbreak to optimize the deployment of resistant crop varieties. We examine differences between infection in the field and assays performed in the laboratory to draw awareness of possible misinformation concerning plant resistance or susceptibility. We discuss key data considered useful for reporting disease outbreaks, sampling bias, and suggestions for improving data quality. We also touch on the knowledge gap in the state-of-the-art literature regarding disease dispersal and transmission. We use a recent case study to exemplify the gaps mentioned. We conclude by highlighting potential actions that may contribute to food security and to closing of the yield gap.

Molecular-Phylogenetic Characterization of Xanthomonas hortorum pv. pelargonii Strains Causing Leaf Spot of Geraniums in Iran.

Bacterial blight and leaf spot of geraniums is a destructive disease of cultivated Pelargonium species around the world. During 2020 to 2021, surveys were conducted in seven geranium-growing provinces of Iran to monitor the status of bacterial blight and leaf spot disease. The disease was observed in six surveyed provinces varying in the extent of occurrence and severity. Twenty-two gram-negative pale-yellow bacterial strains resembling members of Xanthomonas were isolated from symptomatic leaves and stems. Pathogenicity and host range assays showed that the bacterial strains were pathogenic on Pelargonium grandiflorum, P. graveolens, P. peltatum, and P. zonale. All strains were positive for a PCR test using the primer pair XcpM1/XcpM2, which is specific for X. hortorum pv. pelargonii. Phylogenetic analysis using the sequences of gyrB and lepA genes showed that the 22 strains clustered in a clade among the sequences of X. hortorum pv. pelargonii strains retrieved from GenBank but were distinct from the other pathovars of X. hortorum. BOX-PCR-based fingerprinting using BOX-A1R primer revealed that the strains isolated in this study were grouped into two clusters, while no distinct correlation was observed between the host/area of isolation and BOX-PCR fingerprinting. None of the strains obtained in this study nor the reference strain of the pathogen produced bacteriocin against each other. Results obtained in this study shed light on the geographic distribution, taxonomic status, and host range of the bacterial blight and leaf spot pathogen of geraniums in Iran, paving the path for further research on disease management.

Morphological, Biochemical and Molecular Characterization of the Causal Agent of Bacterial Panicle Blight Disease of Rice (BPB) In Selected Rice Production Zones of Zamfara State

Morphological, Biochemical and Molecular Characterization of the Causal Agent of Bacterial Panicle Blight Disease of Rice (BPB) In Selected Rice Production Zones of Zamfara State

Impact of IPM practices on microbial population and disease development in transplanted and direct-seeded rice.

Integrated pest management (IPM) is a comprehensive approach to managing diseases, focusing on combining various strategies to reduce pathogen populations effectively and in an environmentally conscious way. We investigated the effects of IPM on beneficial microbial populations and its relationship with pathogen populations in both direct-seeded rice (DSR) and transplanted rice (TR) systems. This study demonstrates that IPM practices have significantly higher populations of beneficial microbes, such as Trichoderma harzianum and Pseudomonas fluorescens, and lower level of the pathogen Fusarium verticillioides compared to non-IPM (farmer practices). The average mean population of T. harzianum was 6.38 × 103 CFU/g in IPM compared to 3.22 × 103 CFU/g in non-IPM during 2019 in TR at Bambawad. P. fluorescens mean population in 2019 was significantly higher in IPM (4.67 × 103 CFU/g) than in non-IPM (3.82 × 103 CFU/g) at the Karnal location in DSR. The F. verticillioides populations were significantly lower in IPM fields (9.46 × 103 CFU/g) compared to non-IPM fields (11.48 × 103 CFU/g) during 2017 at Haridwar in TR. Over three years, a significant increase in the populations of beneficial microbes in IPM plots was observed in all three locations of both TR and DSR, highlighting the sustainable impact of IPM practices. Disease dynamics analysis revealed that IPM effectively managed key diseases in both DSR and TR systems, with significant correlations between microbial density and disease severity. A significant positive correlation was recorded between F. verticillioides population and bakanae incidence at all three locations. Sheath blight incidence was negatively correlated with P. fluorescens population in both TR and DSR. In DSR, bacterial blight and brown spot diseases are reduced with the increased population of T. harzianum. Bioagents T. harzianum and P. fluorescens reduced disease incidence, underscoring the role of beneficial microbes in disease suppression and their importance for sustainable production using IPM practices.

Prevalence and characterization of Xanthomonas axonopodis pv. cyamopsidis causing bacterial blight of clusterbean in the semi-arid region of North Gujarat

The bacterial blight caused by Xanthomonas axonopodis pv. cyamopsidis is the most widespread and destructive disease of clusterbean. The present study aimed to survey the major clusterbean growing areas, expanding in five districts i.e., Banaskantha, Patan, Sabarkantha, Mehsana and Aravali of North Gujarat. The study found that bacterial blight disease is prevalent in Idar, Ambaji, Danta, Sanali, Khedbramha, Shamalaji, Patan, Bhiloda, Visnagar, Deesa and Amirgadh. The highest mean disease incidence (28.44%) was recorded in Idar, Sabarkantha. Based on the gram straining it was observed that the test bacterium was gram-negative and rod-shaped. Further, the biochemical tests, such as starch hydrolysis, gelatin liquefaction, hydrogen sulphide production, catalase, and acid production from different sugars viz., sucrose, maltose, and dextrose showed a positive reaction, except, acid production from mannitol was negative. Based on the morphological, biochemical, and pathogenic characteristics, the pathogen was identified as Xanthomonas axonopodis pv. cyamopsidis.

Exogenously applied silver nanoparticles (AgNPs) differentially affect bacterial blight disease control in twenty-seven wheat cultivars

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.

First Report of Bacterial Leaf Blight Disease of Rice Caused by Pantoea ananatis in Yunnan Province, China

First Report of Bacterial Leaf Blight Disease of Rice Caused by <i>Pantoea ananatis</i> in Yunnan Province, China

Association between molecular markers and resistance to bacterial blight using binary logistic analysis

The most effective strategy for managing wheat bacterial blight caused by Pseudomonas syringae pv. syringae is believed to be the use of resistant cultivars. Researching the correlation between molecular markers and stress resistance can expedite the plant breeding process. The current study aims to evaluate the response of 27 bread wheat cultivars to bacterial blight disease in order to identify resistant and susceptible cultivars and to pinpoint ISSR molecular markers associated with bacterial blight resistance genes. ISSR markers are recommended for assessing a plant's disease resistance. This experiment is focused on identifying ISSR molecular markers linked to bacterial blight resistance. After applying the bacterial solution to the leaves, we performed sampling to determine the infection percentage in the leaves at different intervals (7, 14, and 18 days after spraying). In most cultivars, the average leaf infection percentage decreased 18 days after spraying on young leaves. However, in some cultivars such as Niknegad, Darab2, and Zarin, leaf infection increased in older leaves and reached up to 100% necrosis. In our study, 12 ISSR primers generated a total of 170 bands, with 156 being polymorphic. The primers F10 and F5 showed the highest polymorphism, while the F7 primer exhibited the lowest polymorphism. Cluster analysis grouped these cultivars into four categories. The resistant group included Qods, Omid, and Atrak cultivars, while the semi-resistant and susceptible groups comprised the rest of the cultivars. Through binary logistic analysis, we identified three Super oxide dismutase-related genes that contribute to plant resistance to bacterial blight. These genes were linked to the F3, F5, and F12 primers in regions I (1500 bp), T (1000 bp), and G (850 bp), respectively. We also identified seven susceptibility-associated genes. Atrak, Omid, and Qods cultivars exhibited resistance against bacterial blight, and three genes associated with this resistance were linked to the F3, F5, and F12 primers. These markers can be used for screening or transferring tolerance to other wheat cultivars in breeding programs.

Hybridizing Long Short-Term Memory and Bi-Directional Long Short-Term Memory Models for Efficient Classification: A Study on Xanthomonas axonopodis pv. phaseoli (XaP) in Two Bean Varieties

This study was conducted on Xanthomonas axonopodis pv, which causes significant economic losses in the agricultural sector. Here, we study a common bacterial blight disease caused by the phaseoli (XaP) bacterial pathogen on Üstün42 and Akbulut bean genera. In this study, a total of 4000 images, healthy and diseased, were used for both bean breeds. These images were classified by AlexNet, VGG16, and VGG19 models. Later, reclassification was performed by applying pre-processing to the raw images. According to the results obtained, the accuracy rates of the pre-processed images classified by the VGG19, VGG16 and AlexNet models were determined as 0.9213, 0.9125 and 0.8950, respectively. The models were then hybridized with LSTM and BiLSTM for raw and pre-processed images and new models were created. When the performance of these hybrid models was evaluated, it was found that the models hybridized with LSTM were more successful than the simple models, while the models hybridized with BiLSTM gave better results than the models hybridized with LSTM. In particular, the VGG19+BiLSTM model attracted attention by achieving 94.25% classification accuracy with pre-processed images. This study emphasizes the effectiveness of image processing techniques in agriculture in the field of disease detection and is important as a new dataset in the literature for evaluating the performance of hybridized models.

Salicylic acid application against bacterial blight resistance in Xa21-introgression Thai rice cultivar ‘Phitsanulok 2’

Rice cultivar ‘Phitsanulok 2’ (‘PSL2’) is popularly grown in lower-northern Thailand, because it has good agricultural traits with high-quality and high-yield grains. However, one significant limitation of rice ‘PSL2’ is its susceptibility to bacterial blight (BB) disease caused by bacteria &lt;i&gt;Xanthomonas oryzae&lt;/i&gt; pv. &lt;i&gt;oryzae (Xoo)&lt;/i&gt;, leading to considerable yield losses. Effort approaches have been used to enhance the BB resistance of rice ‘PSL2’ by introducing the resistance gene &lt;i&gt;Xa21&lt;/i&gt; and using salicylic acid (SA). Thus, the objective of this study was to determine the effects of SA application on BB disease reduction in rice cultivars (‘PSL2’, ‘IRBB21’, and backcrossed lines ‘PSL2-&lt;i&gt;Xa21’&lt;/i&gt; in BC&lt;sub&gt;4&lt;/sub&gt;F&lt;sub&gt;6&lt;/sub&gt;) after&lt;i&gt; Xoo&lt;/i&gt;16PK002 inoculation, compared to a mock treatment control. The results showed that the SA-pretreated rice (2mM) exhibited significantly induced upregulation of the &lt;i&gt;Xa21&lt;/i&gt; gene expression before the &lt;i&gt;Xoo&lt;/i&gt;16PK002-infected rice cultivars ‘IRBB21’ and ‘PSL2-&lt;i&gt;Xa21&lt;/i&gt;-BC&lt;sub&gt;4&lt;/sub&gt;F&lt;sub&gt;6&lt;/sub&gt;’. Additionally, the SA-pretreated rice ‘PSL2-&lt;i&gt;Xa21&lt;/i&gt;-BC&lt;sub&gt;4&lt;/sub&gt;F&lt;sub&gt;6&lt;/sub&gt;’ demonstrated significant suppression of &lt;i&gt;Xoo&lt;/i&gt;16PK002 proliferation (from 1.4 to 2.4-fold reduction), compared to the H&lt;sub&gt;2&lt;/sub&gt;O pretreatment. Similarly, the SA-pretreated rice ‘PSL2-&lt;i&gt;Xa21&lt;/i&gt;-BC&lt;sub&gt;4&lt;/sub&gt;F&lt;sub&gt;6&lt;/sub&gt;’ exhibited increased resistance against BB disease, i.e. reduced lesion lengths (10.0-10.9 cm at 14 DAI and 24.6-28.0 cm at 21 DAI), compared to the water pretreatment (16.8-18.0 cm at 14 DAI and 34.9-35.1 cm at 21 DAI). In summary, the application of the SA-pretreatment in the rice introgression lines ‘PSL2-&lt;i&gt;Xa21&lt;/i&gt;-BC&lt;sub&gt;4&lt;/sub&gt;F&lt;sub&gt;6&lt;/sub&gt;’ resulted in improved defense mechanisms against bacteria &lt;i&gt;Xoo&lt;/i&gt;16PK002 through reduced appearance of symptoms and inhibited &lt;i&gt;Xoo&lt;/i&gt; multiplication.