Search

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui 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.)

[Objective]Biocontrol potential and genome information of strain AH were analyzed to reveal mechanism of disease prevention and explore gene resources of secondary metabolites.[Method]The method of spreading plates was used to screen antagonistic strains from rice leaves.The species was identified by morphological, 16S rDNA and gyrB sequencing and phylogenetic analysis.The flat standoff test and spraying bacterial suspension in field clarified its biocontrol potential.Subsequently, the genome sequence of AH strain was obtained using a third generation Pacbio SMRT sequencing platform and second-generation Illumina sequencing technology.Then, genome assembly, gene prediction, function annotation, and secondary metabolite biosynthetic gene cluster prediction were performed.[Result]AH was a short rod strain, belonged to Pseudomonas putida,and showed broad-spectrum antimicrobial activity against Magnaporthe oryzae,Phoma sp.,Rhizoctonia solani,and Xanthomonas oryzae.Spraying AH suspension significantly reduced disease grade caused by bacterial blight and blast disease.Antibiotic susceptibility testing revealed that AH showed high sensitivity to aminoglycoside antibiotics.The total length of AH genome was 5 889 125 bp, encoding 5 215 genes with 63.74% GC content, including 19 rRNA,77 tRNA and 78 nRNA.And, eight secondary metabolite synthesis gene clusters were predicted by antiSMASH platform in AH genome.[Conclusion]Based on good biocontrol potential of AH strain, the analysis of deep mechanism can provide scientific basis for disease prevention and control. [ABSTRACT FROM AUTHOR]

Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease, which threatens rice production around the world. Efficient infection of rice leaves by Xoo depends on its ability to obtain nutrients from the plant and to cope with the host defence responses. Vitamin B6 (VB6) is essential to the growth of all organisms, but bacteria and plants use different biosynthesis pathways, meaning VB6 biosynthesis might be attractive as an antibacterial target. In bacteria, deoxyxylose 5‐phosphate (DXP)‐dependent and deoxyxylose 5‐phosphate‐independent biosynthesis pathways can produce VB6. However, the Xoo VB6 biosynthesis pathway has not been experimentally identified, and its role in Xoo virulence remains unclear. Here, we analysed the VB6 biosynthesis pathway in Xoo and its role in host–pathogen interactions. PdxA and PdxJ are key components for DXP‐dependent VB6 biosynthesis; we found that Xoo mutants containing mutations in these two putative genes (pdxA and pdxJ) were fully auxotrophic for VB6, demonstrating that Xoo VB6 de novo biosynthesis is DXP‐dependent. We also found that mutation of these key genes (pdxA and pdxJ) significantly reduced Xoo virulence in rice. These results suggest that VB6 de novo biosynthesis is essential for Xoo virulence. [ABSTRACT FROM AUTHOR]

The rice XA21 and XA3 pattern receptor kinases, derived from Oryza longistaminata and an Oryza. sativa japonica cultivar Wase Aikoku 3, respectively, confer resistance to strains of the Gram-negative bacterium Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight disease. Previously, we showed that transfer of Xa21 to the model rice cultivar Kitaake enhances resistance to Xoo. In this manuscript we demonstrate that Kitaake expressing Xa3 confers resistance to Xoo strain PXO79 and that the stress-related marker genes PR10b and KO5 are upregulated in Xoo-infected Xa3 rice leaves. We also show that rice somatic embryogenesis receptor kinase 2 (OsSERK2) positively regulates XA3-mediated immunity in Kitaake. We found that overexpression of XA21 binding protein 15 (XB15) and XB24, two negative regulators of XA21-mediated immunity, do not affect XA3-mediated immunity in the Kitaake genetic background. Our results indicate that the rice immune receptors XA21 and XA3 employ both shared and distinct signaling components in their response to Xoo. The results are important to further understand pathogen-associated molecular pattern (PAMP)-triggered immunity in rice. Furthermore, the presence of Kitaake rice carrying Xa3 will facilitate genetic research to study the XA3-mediated immunity.

Growing resistant rice cultivars is the most effective strategy to control bacterial blight (BB), a devastating disease caused by Xanthomonas oryzae pv. oryzae (Xoo). Screening resistant germplasm and identifying resistance (R) genes are prerequisites for breeding resistant rice cultivars. We conducted a genome-wide association study (GWAS) to detect quantitative trait loci (QTL) associated with BB resistance using 359 East Asian temperate Japonica accessions inoculated with two Chinese Xoo strains (KS6-6 and GV) and one Philippine Xoo strain (PXO99A). Based on the 55K SNPs Array dataset of the 359 Japonica accessions, eight QTL were identified on rice chromosomes 1, 2, 4, 10, and 11. Four of the QTL coincided with previously reported QTL, and four were novel loci. Six R genes were localized in the qBBV-11.1, qBBV-11.2, and qBBV-11.3 loci on chromosome 11 in this Japonica collection. Haplotype analysis revealed candidate genes associated with BB resistance in each QTL. Notably, LOC_Os11g47290 in qBBV-11.3, encoding a leucine-rich repeat receptor-like kinase, was a candidate gene associated with resistance to the virulent strain GV. Knockout mutants of Nipponbare with the susceptible haplotype of LOC_Os11g47290 exhibited significantly improved BB resistance. These results will be useful for cloning BB resistance genes and breeding resistant rice cultivars. [ABSTRACT FROM AUTHOR]

Abstract Background The rice (Oryza sativa) gene Xa7 has been hypothesized to be a typical executor resistance gene against Xanthomonas oryzae pv. oryzae (Xoo), and has conferred durable resistance in the field for decades. Its identity and the molecular mechanisms underlying this resistance remain elusive. Results Here, we filled in gaps of genome in Xa7 mapping locus via BAC library construction, revealing the presence of a 100-kb non-collinear sequence in the line IRBB7 compared with Nipponbare reference genomes. Complementary transformation with sequentially overlapping subclones of the BACs demonstrated that Xa7 is an orphan gene, encoding a small novel protein distinct from any other resistance proteins reported. A 27-bp effector binding element (EBE) in the Xa7 promoter is essential for AvrXa7-inducing expression model. XA7 is anchored in the endoplasmic reticulum membrane and triggers programmed cell death in rice and tobacco (Nicotiana benthamiana). The Xa7 gene is absent in most cultivars, landraces, and wild rice accessions, but highly homologs of XA7 were identified in Leersia perrieri, the nearest outgroup of the genus Oryza. Conclusions Xa7 acts as a trap to perceive AvrXa7 via EBEAvrXa7 in its promoter, leading to the initiation of resistant reaction. Since EBEAvrXa7 is ubiquitous in promoter of rice susceptible gene SWEET14, the elevated expression of which is conducive to the proliferation of Xoo, that lends a great benefit for the Xoo strains retaining AvrXa7. As a result, varieties harboring Xa7 would show more durable resistance in the field. Xa7 alleles analysis suggests that the discovery of new resistance genes could be extended beyond wild rice, to include wild grasses such as Leersia species.

Growing resistant rice cultivars is the most effective strategy to control bacterial blight (BB), a devastating disease caused by Xanthomonas oryzae pv. oryzae (Xoo). Screening resistant germplasm and identifying resistance (R) genes are prerequisites for breeding resistant rice cultivars. We conducted a genome-wide association study (GWAS) to detect quantitative trait loci (QTL) associated with BB resistance using 359 East Asian temperate Japonica accessions inoculated with two Chinese Xoo strains (KS6-6 and GV) and one Philippine Xoo strain (PXO99A). Based on the 55K SNPs Array dataset of the 359 Japonica accessions, eight QTL were identified on rice chromosomes 1, 2, 4, 10, and 11. Four of the QTL coincided with previously reported QTL, and four were novel loci. Six R genes were localized in the qBBV-11.1, qBBV-11.2, and qBBV-11.3 loci on chromosome 11 in this Japonica collection. Haplotype analysis revealed candidate genes associated with BB resistance in each QTL. Notably, LOC_Os11g47290 in qBBV-11.3, encoding a leucine-rich repeat receptor-like kinase, was a candidate gene associated with resistance to the virulent strain GV. Knockout mutants of Nipponbare with the susceptible haplotype of LOC_Os11g47290 exhibited significantly improved BB resistance. These results will be useful for cloning BB resistance genes and breeding resistant rice cultivars.

To discover novel microbial pesticide for controlling rice bacterial disease, polymyxin B1 and E2 were firstly isolated from the supernatant of fermentation broth of Paenibacillus polymyxa Y-1 by bioactivity tracking separation. It is shown that polymyxin B1 and E2 had remarkable in vitro inhibitory activities to Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) with the EC50 values of 0.19 μg/ml and 0.21 μg/ml against Xoo , and 0.32 μg/ml and 0.41 μg/ml against Xoc , respectively, which were better than those of Zhongshengmycin (0.31 μg/ml and 0.73 μg/ml) and Bismerthiazol (77.48 μg/ml and 85.30 μg/ml). Polymyxins B1 and E2 had good protection and curative activities against rice bacterial leaf blight (BLB) and rice bacterial leaf streak (BLS) in vivo. The protection and curative activities of polymyxins B1 (45.8 and 35.8%, respectively) and E2 (41.2 and 37.0%, respectively) to BLB were superior to those of Zhongshengmycin (34.8 and 29.8%, respectively) and Bismerthiazol (38.0 and 33.5%, respectively). Meanwhile, the protection and curative activities of polymyxins B1 (44.8 and 39.8%, respectively) and E2 (42.9 and 39.9%, respectively) to BLS were also superior to those of Zhongshengmycin (39.7 and 32.0%, respectively) and Bismerthiazol (41.5 and 34.3%, respectively). Polymyxin B1 exerted the anti-pesticide properties via destroying the cell integrity of Xoo , reducing its infectivity and enhancing rice resistance against pathogens through activating the phenylpropanoid biosynthesis pathway of rice. It is indicated that polymyxin B1 and E2 were potential microbial pesticides for controlling rice bacterial disease. [ABSTRACT FROM AUTHOR]

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious bacterial diseases that hinder the normal growth and production of rice, which greatly reduces the quality and yield of rice. The effect of traditional methods such as chemical control is often not ideal. A series of production practices have shown that among the numerous methods for BB controlling, breeding and using resistant varieties are the most economical, effective, and environmentally friendly, and the important basis for BB resistance breeding is the exploration of resistance genes and their functional research. So far, 44 rice BB resistance genes have been identified and confirmed by international registration or reported in journals, of which 15 have been successfully cloned and characterized. In this paper, research progress in recent years is reviewed mainly on the identification, map-based cloning, molecular resistance mechanism, and application in rice breeding of these BB resistance genes, and the future influence and direction of the remained research for rice BB resistance breeding are also prospected. [ABSTRACT FROM AUTHOR]

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious bacterial diseases that hinder the normal growth and production of rice, which greatly reduces the quality and yield of rice. The effect of traditional methods such as chemical control is often not ideal. A series of production practices have shown that among the numerous methods for BB controlling, breeding and using resistant varieties are the most economical, effective, and environmentally friendly, and the important basis for BB resistance breeding is the exploration of resistance genes and their functional research. So far, 44 rice BB resistance genes have been identified and confirmed by international registration or reported in journals, of which 15 have been successfully cloned and characterized. In this paper, research progress in recent years is reviewed mainly on the identification, map-based cloning, molecular resistance mechanism, and application in rice breeding of these BB resistance genes, and the future influence and direction of the remained research for rice BB resistance breeding are also prospected.

To discover novel microbial pesticide for controlling rice bacterial disease, polymyxin B1 and E2 were firstly isolated from the supernatant of fermentation broth of Paenibacillus polymyxa Y-1 by bioactivity tracking separation. It is shown that polymyxin B1 and E2 had remarkable in vitro inhibitory activities to Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) with the EC50 values of 0.19 μg/ml and 0.21 μg/ml against Xoo, and 0.32 μg/ml and 0.41 μg/ml against Xoc, respectively, which were better than those of Zhongshengmycin (0.31 μg/ml and 0.73 μg/ml) and Bismerthiazol (77.48 μg/ml and 85.30 μg/ml). Polymyxins B1 and E2 had good protection and curative activities against rice bacterial leaf blight (BLB) and rice bacterial leaf streak (BLS) in vivo. The protection and curative activities of polymyxins B1 (45.8 and 35.8%, respectively) and E2 (41.2 and 37.0%, respectively) to BLB were superior to those of Zhongshengmycin (34.8 and 29.8%, respectively) and Bismerthiazol (38.0 and 33.5%, respectively). Meanwhile, the protection and curative activities of polymyxins B1 (44.8 and 39.8%, respectively) and E2 (42.9 and 39.9%, respectively) to BLS were also superior to those of Zhongshengmycin (39.7 and 32.0%, respectively) and Bismerthiazol (41.5 and 34.3%, respectively). Polymyxin B1 exerted the anti-pesticide properties via destroying the cell integrity of Xoo, reducing its infectivity and enhancing rice resistance against pathogens through activating the phenylpropanoid biosynthesis pathway of rice. It is indicated that polymyxin B1 and E2 were potential microbial pesticides for controlling rice bacterial disease.

Bacterial blight caused by Xanthomonas oryzae pv. oryzae is the most destructive bacterial disease in rice production, and cultivating new disease-resistance variety by mining and utilizing the novel disease resistance genes is one of the most effective ways to control this disease. In our study, a population of 139 recombinant inbred lines (RILs) derived from super hybrid rice Xieyou 9308, between the parents of which there was genetic difference in resistance to bacterial blight, were inoculated with four Xoo strains. A genome-wide association study (GWAS) was carried out using 476,505 SNPs for the lesion length as a quantitative phenotype. The result revealed that a total of 109 significant SNPs including two genes encoding NBS-LRR containing proteins were detected to be significantly difference at P < 1x10-4 for four Xoo strains-treated lesions, accounting for phenotype variation of 59.78%-63.29%, respectively. Furthermore, 25 SNPs located in/nearby 19 candidate genes were identified by the CR4 inoculation, accounting for 61.00%. Relative expression analysis of two selected candidate genes, LOC_Os11g43420 and LOC_Os11g45930, demonstrated their higher expression levels in the resistant cultivar Zhonghui 9308 than in the susceptible variety Xieqingzao B, suggesting that these two genes might positively regulated bacterial blight resistance. Phylogenetic tree analysis indicated that these two genes were different from the previous cloned resistant genes in evolution, suggesting they were novel disease resistance genes. These results lays a theoretical basis and provides genetic resources for future resistant breeding in rice. [ABSTRACT FROM AUTHOR]

A series of 1,3,4-oxadiazole contained sesquiterpene derivatives were synthesized, and the activity of the target compounds against Xanthomonas oryzae pv. oryzae (Xoo), Xanthomonas axonopodis pv. citri (Xac), and tobacco mosaic virus (TMV) were evaluated. The biological activity results showed that the EC50 values of compounds H4, H8, H11, H12, H14, H16, and H19 for Xac inhibitory activity were 33.3, 42.7, 56.1, 74.5, 37.8, 43.8, and 38.4 μg/ml, respectively. Compounds H4, H8, H15, H19, H22, and H23 had inhibitory effects on Xoo, with EC50 values of 51.0, 43.3, 43.4, 50.5, 74.6, and 51.4 μg/ml, respectively. In particular, the curative and protective activities of compound H8 against Xoo in vivo were 51.9 and 49.3%, respectively. In addition, the EC50 values of the inactivation activity of compounds H4, H5, H9, H10, and H16 against TMV were 69.6, 58.9, 69.4, 43.9, and 60.5 μg/ml, respectively. The results of molecular docking indicated that compound H10 exhibited a strong affinity for TMV-coat protein, with a binding energy of −8.88 kcal/mol. It may inhibit the self-assembly and replication of TMV particles and have an anti-TMV effect, which supports its potential usefulness as an antiviral agent.

Abstract Rice bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most destructive diseases in rice-growing regions worldwide. Zinc thiazole is a novel bactericide and has been applied for BB control for 10 years. However, zinc thiazole is highly insoluble in water and in most organic solvents. In this work, we found for the first time that zinc thiazole can be dissolved in dimethyl sulfoxide (DMSO), and the solubility of zinc thiazole in DMSO is more than 20 mg/mL. Dissolved zinc thiazole at 25 μg/mL significantly inhibited the growth of Xoo by 58.81%. Interestingly, zinc thiazole at 25 μg/mL enhanced the cell division and altered the cell wall integrity of Xoo. The application of dissolved zinc thiazole at 100 μg/mL reduced the incidence of rice bacterial blight (BB) by providing 64.71% control efficacy, while zinc thiazole as suspension concentrate (SC) at 100 μg/mL only provided 43.42% control efficacy. Taken together, this study provides for the first time a method for dissolving zinc thiazole, and may help to better understand the antibacterial mechanism of zinc thiazole.

Background: The rice (Oryza sativa) gene Xa7 has been hypothesized to be a typical executor resistance gene against Xanthomonas oryzae pv. oryzae (Xoo), and has conferred durable resistance in the field for decades. Its identity and the molecular mechanisms underlying this resistance remain elusive. Results: Here, we filled in gaps of genome in Xa7 mapping locus via BAC library construction, revealing the presence of a 100-kb non-collinear sequence in the line IRBB7 compared with Nipponbare reference genomes. Complementary transformation with sequentially overlapping subclones of the BACs demonstrated that Xa7 is an orphan gene, encoding a small novel protein distinct from any other resistance proteins reported. A 27-bp effector binding element (EBE) in the Xa7 promoter is essential for AvrXa7-inducing expression model. XA7 is anchored in the endoplasmic reticulum membrane and triggers programmed cell death in rice and tobacco (Nicotiana benthamiana). The Xa7 gene is absent in most cultivars, landraces, and wild rice accessions, but highly homologs of XA7 were identified in Leersia perrieri, the nearest outgroup of the genus Oryza. Conclusions: Xa7 acts as a trap to perceive AvrXa7 via EBEAvrXa7 in its promoter, leading to the initiation of resistant reaction. Since EBEAvrXa7 is ubiquitous in promoter of rice susceptible gene SWEET14, the elevated expression of which is conducive to the proliferation of Xoo, that lends a great benefit for the Xoo strains retaining AvrXa7. As a result, varieties harboring Xa7 would show more durable resistance in the field. Xa7 alleles analysis suggests that the discovery of new resistance genes could be extended beyond wild rice, to include wild grasses such as Leersia species. [ABSTRACT FROM AUTHOR]

Class III peroxidases (CIII Prxs) play critical roles in plant immunity by scavenging reactive oxygen species (ROS). However, the functions of CIII Prxs in rice (Oryza sativa L.) immunity are largely unexplored. Here, we report a Prx precursor, OsPrx30, that is responsive to the bacterial blight Xanthomonas oryzae pv. oryzae (Xoo). OsPrx30 was primarily expressed in rice roots, leaves, and stems, and its protein product was mainly localized at the endoplasmic reticulum. Overexpression of OsPrx30 enhanced the plant's susceptibility to Xoo by maintaining a high level of peroxidase (POD) activity and reducing the content of H2O2, whereas depletion of OsPrx30 had the opposite effects. Furthermore, we identified an AT‐hook transcription factor, OsATH1, that is specifically bound to the OsPrx30 promoter. As observed in plants overexpressing OsPrx30, depletion of OsATH1 enhanced susceptibility to Xoo. Finally, we demonstrated that depletion of OsATH1 increased histone H3 acetylation at the AT‐rich region of the OsPrx30 promoter. Taken together, these results reveal a mechanism underlying the POD‐induced natural resistance to bacterial diseases and suggest a model for transcription regulation of Prx genes in rice. [ABSTRACT FROM AUTHOR]

Because bacterial blight (BB) disease seriously affects the yield and quality of rice, breeding BB resistant rice is an important priority for plant breeders but the process is time-consuming. The feasibility of using terahertz imaging technology and near-infrared hyperspectral imaging technology to identify BB resistant seeds has therefore been studied. The two-dimensional (2D) spectral images and one-dimensional (1D) spectra provided by both imaging methods were used to build discriminant models based on a deep learning method, the convolutional neural network (CNN), and traditional machine learning methods, support vector machine (SVM), random forest (RF), and partial least squares discriminant analysis (PLS-DA). The highest classification accuracy was achieved by the discriminate model based on CNN using the terahertz absorption spectra. Confusion matrixes were pictured to show the identification details. The t-distributed stochastic neighbor embedding (t-SNE) method was used to visualize the process of CNN data processing. Terahertz imaging technology combined with CNN has great potential to quickly identify BB resistant rice seeds and is more accurate than using near-infrared hyperspectral imaging.

The rice XA21 and XA3 pattern receptor kinases, derived from Oryza longistaminata and an Oryza. sativa japonica cultivar Wase Aikoku 3, respectively, confer resistance to strains of the Gram-negative bacterium Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight disease. Previously, we showed that transfer of Xa21 to the model rice cultivar Kitaake enhances resistance to Xoo. In this manuscript we demonstrate that Kitaake expressing Xa3 confers resistance to Xoo strain PXO79 and that the stress-related marker genes PR10b and KO5 are upregulated in Xoo-infected Xa3 rice leaves. We also show that rice somatic embryogenesis receptor kinase 2 (OsSERK2) positively regulates XA3-mediated immunity in Kitaake. We found that overexpression of XA21 binding protein 15 (XB15) and XB24, two negative regulators of XA21-mediated immunity, do not affect XA3-mediated immunity in the Kitaake genetic background. Our results indicate that the rice immune receptors XA21 and XA3 employ both shared and distinct signaling components in their response to Xoo. The results are important to further understand pathogen-associated molecular pattern (PAMP)-triggered immunity in rice. Furthermore, the presence of Kitaake rice carrying Xa3 will facilitate genetic research to study the XA3-mediated immunity.

Because bacterial blight (BB) disease seriously affects the yield and quality of rice, breeding BB resistant rice is an important priority for plant breeders but the process is time-consuming. The feasibility of using terahertz imaging technology and near-infrared hyperspectral imaging technology to identify BB resistant seeds has therefore been studied. The two-dimensional (2D) spectral images and one-dimensional (1D) spectra provided by both imaging methods were used to build discriminant models based on a deep learning method, the convolutional neural network (CNN), and traditional machine learning methods, support vector machine (SVM), random forest (RF), and partial least squares discriminant analysis (PLS-DA). The highest classification accuracy was achieved by the discriminate model based on CNN using the terahertz absorption spectra. Confusion matrixes were pictured to show the identification details. The t-distributed stochastic neighbor embedding (t-SNE) method was used to visualize the process of CNN data processing. Terahertz imaging technology combined with CNN has great potential to quickly identify BB resistant rice seeds and is more accurate than using near-infrared hyperspectral imaging. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) handle immune response to pathogens by adjusting the function of target genes in plants. However, the experimentally documented miRNA/target modules implicated in the interplay between rice and Xanthomonas oryzae pv. oryzae (Xoo) are still in the early stages. Herein, the expression of osa-miR1432 was induced in resistant genotype IRBB5, but not susceptible genotype IR24, under Xoo strain PXO86 attack. Overexpressed osa-miR1432 heightened rice disease resistance to Xoo, indicated by enhancive enrichment of defense marker genes, raised reactive oxygen species (ROS) levels, repressed bacterial growth and shortened leaf lesion length, whilst the disruptive accumulation of osa-miR1432 accelerated rice susceptibility to Xoo infection. Noticeably, OsCaML2 (LOC_Os03g59770) was experimentally confirmed as a target gene of osa-miR1432, and the overexpressing OsCaML2 transgenic plants exhibited compromised resistance to Xoo infestation. Our results indicate that osa-miR1432 and OsCaML2 were differently responsive to Xoo invasion at the transcriptional level and fine-tune rice resistance to Xoo infection, which may be referable in resistance gene discovery and valuable in the pursuit of improving Xoo resistance in rice breeding.

Abstract The plant hormone jasmonic acid (JA) plays an important role in defense response and plant development. Jasmonate ZIM-domain (JAZ) proteins act as transcriptional repressors of plant responses to JA. In this study, we found that OsNINJA1, which is a JAZ-interacting adaptor protein, plays an important role in JA signaling that is positively regulated by the transcription factor OsMYC2 in rice. The expression of OsNINJA1 was upregulated at an early phase after JA treatment, and OsNINJA1 interacted with several OsJAZ proteins in a C domain-dependent manner. Transgenic rice plants overexpressing OsNINJA1 exhibited a JA-insensitive phenotype and were more susceptible to rice bacterial blight caused by Xanthomonas oryzae pv. oryzae , which is one of the most serious diseases affecting rice. Furthermore, OsNINJA1 negatively affected JA-regulated leaf senescence under dark-induced senescence conditions. Finally, the expression of OsMYC2-responsive pathogenesis-related (PR) genes and senescence-associated genes (SAGs) tended to be downregulated in the OsNINJA1 -overexpressing rice plants. These results indicate that OsNINJA1 acts as a negative regulator of OsMYC2-mediated JA signaling in rice. [ABSTRACT FROM AUTHOR]

The Gram-negative bacterium Pseudomonas taiwanensis is a novel bacterium that uses shrimp shell waste as its sole sources of carbon and nitrogen. It is a versatile bacterium with potential for use in biological control, with activities including toxicity toward insects, fungi, and the rice pathogen Xanthomonas oryzae pv.oryzae (Xoo). In this study, the complete 5.08-Mb genome sequence of P. taiwanensis CMS was determined by a combination of NGS/Sanger sequencing and optical mapping. Comparison of optical maps of seven Pseudomonas species showed that P. taiwanensis is most closely related to P. putida KT 2400. We screened a total of 11,646 individual Tn5-transponson tagged strains to identify genes that are involved in the production and regulation of the iron-chelator pyoverdine in P. taiwanensis, which is a key anti-Xoo factor. Our results indicated that the two-component system (TCS) EnvZ/OmpR plays a positive regulatory role in the production of pyoverdine, whereas the sigma factor RpoS functions as a repressor. The knowledge of the molecular basis of the regulation of pyoverdine by P. taiwanensis provided herein will be useful for its development for use in biological control, including as an anti-Xoo agent.

MicroRNAs (miRNAs) are crucial player in plant-pathogen interaction. While the evidence has demonstrated that rice miRNAs mediate immune response to pathogens invasion, the roles of miRNAs on Xanthomonas oryzae pv. oryzae (Xoo) attack remain be in place. Herein, we monitored the responsive changes of rice miRNAs at 0, 8, 24 h across Xoo strain PXO86 infection in its compatible rice variety IR24 and incompatible variety IRBB5 by small RNA sequencing, and the genes targeted by miRNAs were also detected via degradome technology. The faithfulness of sequencing data was validated through quantitative real-time stem-loop reverse transcription-polymerase chain reaction assay. Bioinformatic analysis showed that the differentially expressed miRNAs could be divided into three immunity-related clusters, and 80 regulatory units were emerged in infection process, which comprises 29 differentially expressed known miRNAs and 38 cleaved targets. Furthermore, the miRNA presumptive function of separate immunity cluster in rice-Xoo interplay was confirmed through overexpressing osa-miR164a, osa-miR167d and osa-miR159b, and the disruption of regulatory units, osa-miR164a/OsNAC60, osa-miR167d-5p/OsWD40-174 and osa-miR159b/OsMYBGA, OsLRR-RLK2, OsMPK20-4, may reset rice defense response to Xoo infestation in a controllable manner. These findings provide new insights into the complex roles of characteristic miRNAs and their targets in rice-Xoo interactions.

The resistance of dominant rice varieties in Guangzhou against rice blast (Magnaporthe oryzae) and bacterial blight (Xanthomonas oryzae pv. oryzae) were evaluated by artificial inoculation and field natural blast nursery identification. Among 11 varieties tested, seven varieties showed resistance to rice blast, accounting for 63.6%; two varieties were highly resistant, accounting for 18.2%; three varieties were resistant, accounting for 27.3%; two varieties were moderately resistant, accounting for 18.2%; four varieties were susceptible (moderately susceptible), accounting for 36.4%. Varieties showed different resistance against the prevailing pathotype IV of bacterial blight; one variety was resistant, accounting for 9.1%; three varieties were moderately resistant, accounting for 27.3%; five varieties were moderately susceptible, accounting for 45.5%; one variety was susceptible, accounting for 9.1%; one variety was highly susceptible, accounting for 9.1%; all varieties tested showed susceptible to the virulent pathotype V. Huanghuazhan, Yuejingsimiao 2 and Fengxiuzhan showed resistance against both bacterial blight (pathotype IV) and rice blast, accounting for 27.3%. It is helpful to reduce the production risk by extending such dominant rice varieties with good resistance to rice blast and bacterial blight. [ABSTRACT FROM AUTHOR]

Spotted leaf mutant belongs to a class of mutants that can produce necrotic lesions spontaneously in plants without any attack by pathogens. These mutants have no beneficial effect on plant productivity but provide a unique opportunity to study programmed cell death in plant defense responses. A novel rice spotted leaf mutant (spl30) was isolated through low-energy heavy ion irradiation. Lesion expression was sensitive to light and humidity. The spl30 mutant caused a decrease in chlorophyll and soluble protein content, with marked accumulation of reactive oxygen species (ROS) around the lesions. In addition, the spl30 mutant significantly enhanced resistance to rice bacterial blight (X. oryzae pv. oryzae) from China (C1-C7). The use of SSR markers showed that the spl30 gene was located between markers XSN2 and XSN4. The genetic distance between the spl30 gene and XSN2 and between spl30 and XSN4 was 1.7 cM and 0.2 cM, respectively. The spl30 gene is a new gene involved in lesion production and may be related to programmed cell death in rice. The ability of this mutant to confer broad resistance to bacterial blight provides a model for studying the interaction between plants and pathogenic bacteria.

Jasmonic acid (JA) is a plant hormone that plays an important role in the defense response and stable growth of rice. In this study, we investigated the role of the JA-responsive valine-glutamine (VQ)-motif-containing protein OsVQ13 in JA signaling in rice. OsVQ13 was primarily located in the nucleus and cytoplasm. The transgenic rice plants overexpressing OsVQ13 exhibited a JA-hypersensitive phenotype and increased JA-induced resistance to Xanthomonas oryzae pv. oryzae (Xoo), which is the bacteria that causes rice bacterial blight, one of the most serious diseases in rice. Furthermore, we identified a mitogen-activated protein kinase, OsMPK6, as an OsVQ13-associating protein. The expression of genes regulated by OsWRKY45, an important WRKY-type transcription factor for Xoo resistance that is known to be regulated by OsMPK6, was upregulated in OsVQ13-overexpressing rice plants. The grain size of OsVQ13-overexpressing rice plants was also larger than that of the wild type. These results indicated that OsVQ13 positively regulated JA signaling by activating the OsMPK6−OsWRKY45 signaling pathway in rice.

Rice ( Oryza sativa L.) is the staple food crop for more than half of the world's population. The development of hybrid rice is a practical approach to increase rice production. However, rice production was frequently affected by biotic and abiotic stresses. Rice blast and bacterial blight are two major diseases in rice growing regions. Rice plantation is also frequently affected by short-term submergence or seasonal floods in wet seasons and drought in dry seasons. The utilization of natural disease resistance ( R) genes and stress tolerance genes in rice breeding is the most economic and efficient way to combat or adapt to these biotic and abiotic stresses. Rice cultivar 9311 is widely planted rice variety, either as inbred rice or the paternal line of two-line hybrid rice. Here, we report the pyramiding of rice blast R gene Pi9, bacterial blight R genes Xa21 and Xa27, and submergence tolerance gene Sub1A in 9311 genetic background through backcrossing and marker-assisted selection. The improved rice line, designated as 49311, theoretically possesses 99.2% genetic background of 9311. 49311 and its hybrid rice, GZ63S/49311, conferred disease resistance to rice blast and bacterial blight and showed tolerance to submergence for over 18 days without significant loss of viability. 49311 and its hybrids had similar agronomic traits and grain quality to 9311 and the control hybrid rice, respectively. The development of 49311 provides an improved paternal line for two-line hybrid rice production with disease resistance to rice blast and bacterial blight and tolerance to submergence. [ABSTRACT FROM AUTHOR]

Aim To identify the active compounds from the Streptomyces sp. MJM4426 that can protect rice from bacterial blight disease ( BB), and to evaluate the potential of this Streptomyces strains and the compound for biocontrol of rice bacterial blight disease. Methods and Results The ethyl acetate extract of Streptomyces sp. MJM4426 can significantly protect rice leaf explants from the infection of Xanthomonas oryzae pv. oryzae KACC 10331 ( Xoo), the pathogen which cause BB. To identify the active compounds, the ethyl acetate extract of Streptomyces sp. MJM4426 was fractionated through a Sephadex LH-20 column chromatography, and further purified by preparative HPLC guided by the inhibitory activity against BB in rice leaf explants. UPLC-Q- TOF/ MS analysis showed the active compound displayed its m/ z values at [M+H]+ 467·2086 and [M+ FA−H]− 511·1963, and the molecular formula was estimated as C28H26N4O3 which is identical to commercial standard staurosporine. In this study, the isolated staurosporine dramatically suppressed bacterial blight in rice leaf explants with the lowest concentration at 12·5 μmol l−1, however, it exhibited low inhibitory activity against Xoo with the MIC value at 256 μg ml−1. In addition, greenhouse study showed both crude extract and purified staurosporine can suppress the bacterial blight at the concentration of 5000 and 200 μg ml−1 respectively. Conclusion Streptomyces sp. MJM4426 can protect rice leaf explants from the infection of Xoo by producing staurosporine, but not by direct inhibitory activity against Xoo. Significance and Impact of the Study This is the first report that staurosporine can protect rice leaf against bacterial blight disease and showed the potential of Streptomyces sp. MJM4426 as an alternative to chemical bactericide for bacterial blight disease in rice. [ABSTRACT FROM AUTHOR]

Blast and bacterial blight are serious diseases around the major rice-growing area in the world. Genetic breeding by using rice resistance genes per se would be an economic and efficient way to combat these biotic stresses. Guangzhan63S (GZ63S) is an elite photoperiodic and thermo-sensitive male sterile (P/TGMS) line from which many widely cultivated two-line super-hybrid varieties in the Yangzi River basin have been derived. However, GZ63S is susceptible to rice blast as well as bacterial blight. Here, we report the pyramiding of the blast resistance gene Pi9 and the bacterial blight resistance gene Xa23 in GZ63S and its derived hybrid, Liangyou6326, by marker-assisted selection (MAS). The improved sterile line and its derived hybrid showed high levels of resistance to all eight tested Xanthomonas oryzae pv. oryzae strains. Moreover, they demonstrated high levels of resistance to leaf blast at the seedling stage and to neck blast in most natural sites at the maturity stage. The improved GZ63S and its derived hybrid had maintained elite agronomic traits of original variety under normal growth conditions. When exposed to disease stresses, the improved hybrid represented much better agronomic traits than the original variety. Our results indicate that pyramiding the Pi9 and Xa23 genes by MAS is useful for breeding blast- and bacterial blight-resistant hybrids. [ABSTRACT FROM AUTHOR]

Rice is a staple food crop for more than half of the world's population. However, rice production is affected by many types of abiotic and biotic stress. Genetic breeding by utilizing natural resistance or tolerance genes is the most economic and efficient way to combat or adapt to these stresses. Khao Dawk Mali 105 (KDML 105) is an elite cultivar of aromatic rice mainly grown in Thailand. However, the production of KDML 105 is affected by lodging problems due to its tall plant type, regular flash floods or short-term submergence during the monsoon season, and diseases such as blast and bacterial blight. Here we report the pyramiding of semi-dwarf gene sd1, submergence tolerance gene Sub1A, blast resistance gene Pi9 and bacterial blight resistance genes Xa21 and Xa27 in KDML 105 by marker-assisted selection. The improved line, designated T5105, has a semi-dwarf phenotype with improved lodging resistance and a greater harvest index. T5105 survives after 2 weeks of complete submergence without significant loss of viability. T5105 confers high resistance to all five Magnaporthe oryzae isolates tested and provides resistance or moderate resistance to 25 of the 27 Xanthomonas oryzae pv. oryzae strains tested. In addition, T5105 produced higher yield than KDML 105 in two field trials and retains similar good grain quality to KDML 105. The development of T5105 provides a new line to boost the production of high-quality aromatic rice in tropical regions. [ABSTRACT FROM AUTHOR]

Nucleotide-binding site leucine-rich repeat (NB-LRR) genes play important roles in plant disease resistance. Due to its similarity to Rp1 in maize ( Zea mays), a novel NB-LRR gene was isolated from rice and designated as OsRP1L1 ( Oryza sativa Rp1-like 1). Analysis of expression of a super green fluorescent protein ( sGFP) fusion gene revealed that the OsRP1L1 protein localizes to the nucleolus. Expression patterns suggested that OsRP1L1 was involved in responses to several plant growth regulators (PGRs) and environmental stresses. To explore its function in bacterial blight (BB) resistance, OsRP1L1 was cloned and overexpressed in a susceptible japonica rice cultivar. Overexpression of OsRP1L1 moderately elevated the resistance of plants to Xanthomonas oryzae pv. oryzae strains PXO86 and PXO341. Transcriptome analysis showed that plants overexpressing OsRP1L1 had small changes in their transcriptome, with 26 genes showing statistically significant changes of more than two-fold. The most up-regulated transcripts-a DIN1-like gene and a terpene synthase ( TPS) gene-were up-regulated 7.9- and 7.6-fold, respectively. It was also noted that seven of the up-regulated genes have also reportedly been induced by overexpression of OsbZIP46, which has been identified recently as a player in ABA sensing. All these findings suggest that OsRP1L1 plays an important role in rice BB resistance, and may be useful as a genetic resource for engineering disease resistance in plants. [ABSTRACT FROM AUTHOR]

Rice bacterial blight and rice bacterial streak are two serious rice diseases and have caused great harm to the production of rice all over the world. To develop an efficient antibacterial agent with a novel target, a series of novel 2- oxo - N -phenylacetamide derivatives containing a dissulfone moiety were synthesized, and their antibacterial activities were evaluated. Among them, compound D 14 exhibited the best antibacterial activities, especially against Xoo and Xoc with EC 50 values of 0.63 and 0.79 mg/L, respectively, which were much better than the commercial control of bismerthiazol ( BT ) (76.59 and 83.35 mg/L, respectively) and thiodiazole copper ( TC ) (91.72 and 114.00 mg/L, respectively). Meanwhile, compound D 14 can interact with a CRP-like protein (Clp) of Pxo99 A and show strong binding activity with Xoo -Clp with a K d value of 0.52 μM, which was far superior to the corresponding K d values of BT (183.94 μM) and TC (222.58 μM). Treatment of D 14 and deletion of the clp gene could significantly reduce the expression of the clp gene and attenuate the virulence of pathogenic bacteria. These results indicated that compound D 14 could be used as a potential novel agricultural bactericide and Clp can be used as a target protein for the control of plant bacterial diseases. This work provided reliable support for developing novel antibacterial agents based on Clp as a target protein.

Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight in rice, interacts with rice plants in a gene-for-gene manner. The specificity of the interaction is dictated by avirulence ( avr) genes in the pathogen and resistance ( R) genes in the host. To date, no avr genes that correspond to recessive R genes have been isolated. We isolated an avrBs3/pthA family gene, avrxa5, from our previously isolated clone p58, which was originally from strain JXOIII. The avrxa5 gene converted the PXO99 strain from compatible to incompatible in rice cultivars containing the recessive xa5 gene, but not in those containing the dominant Xa5 gene. Sequencing indicated that avrxa5, which is highly similar to members of the avrBs3/pthA family, encodes a protein of 1238 amino acid residues with a conserved carboxy-terminal region containing three nuclear localization signals and a transcription activation domain. It has 19.5 34-amino-acid direct repeats, but the 13th amino acid is missing in the fifth and ninth repetitive units. Domain swapping of the repetitive regions between avrxa5 and avrXa7 changed the avirulence specificity of the genes in xa5 and Xa7 rice lines, respectively. This indicates that avrxa5 is distinct from previously characterized avrBs3/pthA members. The specificity of avrxa5 toward recessive xa5 in rice could help us better understand the molecular mechanisms of plant-pathogen specific interactions. [ABSTRACT FROM AUTHOR]

Abstract: The rice bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most devastating bacterial disease of rice worldwide. Because of the rapid changes in the pathogenicity of the pathogen (Xoo), novel BB-resistance genes are always needed for rice (Oryza sativa L.) breeding. In this article, a novel BB-resistance gene was identified from a wild rice (Oryzae ustraliensis) introgression line, C4064, and its chromosomal location was reported. On the basis of the resistance spectrum analysis, C4064 presented resistance to Xoo strains P1 (PXO61), P4 (PXO71), P5 (PXO112), P6 (PXO99), P7 (PXO145), P8 (PXO280), P9 (PXO339), and KX085, but susceptible to P2 (PXO86) and P3 (PXO79). Therefore, the resistance gene harbored in C4064 was a novel BB-resistance gene and tentatively designated as Xa32(t). Furthermore, the chromosomal position of this gene was located using bulked segregant analysis with the help of simple sequence repeat and expressed sequence tag markers. Of the 299 markers tested, 6 markers, i.e., RM27256, RM27274, RM2064, ZCK24, RM6293, and RM5926 on the long arm of chromosome 11, were linked with Xa32(t) with genetic distances of 2.1, 1.0, 1.0, 0.5, 1.5, and 2.6 cM between the resistance gene and the markers, respectively. The resistance gene was located between markers RM6293 and RM5926 at the end side of long arm and the other 4 markers at the centromere side. Finally, Xa32(t) was mapped within a length of 2.0 cM on the long arm of rice chromosome 11. [Copyright &y& Elsevier]

Abstract: Bacterial leaf blight (BB) is a worldwide destructive rice disease caused by pathogen Xanthomonas oryzae pv. oryzae (Xoo). A novel strain of Lysobacter antibioticus, which was isolated from the rhizosphere of rice in Yunnan Province of China, can significantly inhibit the growth of various phytopathogenic bacteria and fungi, especially BB pathogen Xoo. In greenhouse experiments, whole bacterial broth culture (WBC) of strain 13-1 was more effective in reducing BB than other components of the culture, with disease suppression efficiency up to 69.7%. However, bacterial cells re-suspended in water, cell-free culture extracts, and heated cultures also significantly reduced BB severity. Suppression efficiencies ranged from 79.0% to 61.8% for undiluted to 100-fold dilution treatments and from 57.6% to 31.7% when the WBC of strain 13-1 (108 CFU/mL) was applied at 3 days and 7 days prior to pathogen inoculation, respectively. In three field trials, strain 13-1 reduced BB incidence by 73.5%, 78.3%, and 59.1%, respectively. Disease suppression by strain 13-1 varied significantly among different rice cultivars, although efficacy was not directly related to the susceptibility level of the cultivars. Efficacy of biocontrol was also affected by different pathogen isolates, with some isolates of Xoo being more sensitive to 13-1 suppression than others. These results suggest that antibiotics and density of colonization on leaves may be involved for biological control of rice BB by strain 13-1. To our knowledge, this is the first report of L. antibioticus being a potential biocontrol agent for rice bacterial blight. [Copyright &y& Elsevier]

The present study describes the compositional difference of the exopolysaccharide (EPS) produced by Xanthomonas oryzae pv. oryzae strains, BXO1 and BXO8 that show varying degrees of virulence in rice ( Oryza sativa L.). The EPS of X. oryzae pv. oryzae strains, BXO1 and BXO8 was extracted, estimated and characterized using Fourier transform infrared, nuclear magnetic resonance (NMR), high-performance size exclusion chromatography and high-performance anion exchange chromatography (HPAEC) with pulsed amperometric detection (PAD). The 1H-NMR spectra showed the presence of α- or β-anomeric carbon of hexose or pentose, hydrogen next to hydroxyl group and uronic acid of hexose and pentose in the EPS of both BXO1 and BXO8. HPAEC with PAD revealed the presence of arabinose, galactose, glucose, mannose, galacturonic acid and glucuronic acid in both EPSs. In addition, only EPS of BXO8 contained rhamnose and xylose. The most virulent strain, BXO8 produced higher amount of EPS (43.62 μg/ml) than did BXO1 (32.5 μg/ml). Compositional difference of EPS produced by different strains of X. oryzae pv. oryzae might play an important role in host or cultivar specificity and might determine the spectrum of their virulence. Knowledge on EPS may help to understand the mode of action of bacterial pathogens. [ABSTRACT FROM AUTHOR]

Complete resistance (CR) and partial resistance (PR) of rice (Oryza sativa L.) to its bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo), was genetically dissected by using 2 mapping populations and 10 Xoo races. Two CR genes, 50 quantitative resistance loci, and 60 digenic interactions were identified, which showed various degrees of race specificity to the Xoo races. The complex epistasis between these loci led us to the discovery of complex genetic networks underlying the rice defensive system to Xoo. The net- works consisted of two major components: one representing interactions between alleles at the R loci of rice and alleles at the corresponding avirulence loci of Xoo for CR and the other comprising interactions between quantitative resistance loci in rice and their corresponding aggressiveness loci in Xoo for PR. The race specificity of PR and its strong genetic overlap with CR indicate that PR is essentially "weaker" CR. The genetic networks discovered are expected to maintain a high level of the allelic diversity at avirulent loci in the pathogen by stabilizing selection, which may maintain a high allelic diversity at R loci in the host by the frequency- dependent selection. [ABSTRACT FROM AUTHOR]

Asymmetric somatic hybrid plants were produced between cultivated rice (Oryza sativa L.) and wild species [O. meyeriana (Zoll. etMor, exSteud.)] with high resistance to rice bacterial blight. X-ray-irradiated protoplasts of the wild species were used as donor and chemically fused with iodoacetamide-inactivated protoplasts of rice cv. 02428 to produce hybrids. Seventy-two plants were regenerated from 623 calli based on metabolic complementation. The morphological characters of the plants closely resembled that of the rice. Simple sequence repeats were employed to identify their hybridity. Cytological analysis of root-tips revealed that their chromosome number varied in the range of 27–38. The somatic hybrids were inoculated with strains of Xanthamonas oryzae pv. oryzae at adult growth stage and demonstrated the resistance to bacterial blight introgression from the O. meyeriana. [ABSTRACT FROM AUTHOR]

To discover novel microbial pesticide for controlling rice bacterial disease, polymyxin B 1 and E 2 were firstly isolated from the supernatant of fermentation broth of Paenibacillus polymyxa Y-1 by bioactivity tracking separation. It is shown that polymyxin B 1 and E 2 had remarkable in vitro inhibitory activities to Xanthomonas oryzae pv. oryzae ( Xoo ) and Xanthomonas oryzae pv. oryzicola ( Xoc ) with the EC 50 values of 0.19 μg/ml and 0.21 μg/ml against Xoo , and 0.32 μg/ml and 0.41 μg/ml against Xoc , respectively, which were better than those of Zhongshengmycin (0.31 μg/ml and 0.73 μg/ml) and Bismerthiazol (77.48 μg/ml and 85.30 μg/ml). Polymyxins B 1 and E 2 had good protection and curative activities against rice bacterial leaf blight (BLB) and rice bacterial leaf streak (BLS) in vivo . The protection and curative activities of polymyxins B 1 (45.8 and 35.8%, respectively) and E 2 (41.2 and 37.0%, respectively) to BLB were superior to those of Zhongshengmycin (34.8 and 29.8%, respectively) and Bismerthiazol (38.0 and 33.5%, respectively). Meanwhile, the protection and curative activities of polymyxins B 1 (44.8 and 39.8%, respectively) and E 2 (42.9 and 39.9%, respectively) to BLS were also superior to those of Zhongshengmycin (39.7 and 32.0%, respectively) and Bismerthiazol (41.5 and 34.3%, respectively). Polymyxin B 1 exerted the anti-pesticide properties via destroying the cell integrity of Xoo , reducing its infectivity and enhancing rice resistance against pathogens through activating the phenylpropanoid biosynthesis pathway of rice. It is indicated that polymyxin B 1 and E 2 were potential microbial pesticides for controlling rice bacterial disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Yi, Chen and Gan.)

MicroRNAs (miRNAs) handle immune response to pathogens by adjusting the function of target genes in plants. However, the experimentally documented miRNA/target modules implicated in the interplay between rice and Xanthomonas oryzae pv. oryzae (Xoo) are still in the early stages. Herein, the expression of osa-miR1432 was induced in resistant genotype IRBB5, but not susceptible genotype IR24, under Xoo strain PXO86 attack. Overexpressed osa-miR1432 heightened rice disease resistance to Xoo, indicated by enhancive enrichment of defense marker genes, raised reactive oxygen species (ROS) levels, repressed bacterial growth and shortened leaf lesion length, whilst the disruptive accumulation of osa-miR1432 accelerated rice susceptibility to Xoo infection. Noticeably, OsCaML2 (LOC_Os03g59770) was experimentally confirmed as a target gene of osa-miR1432, and the overexpressing OsCaML2 transgenic plants exhibited compromised resistance to Xoo infestation. Our results indicate that osa-miR1432 and OsCaML2 were differently responsive to Xoo invasion at the transcriptional level and fine-tune rice resistance to Xoo infection, which may be referable in resistance gene discovery and valuable in the pursuit of improving Xoo resistance in rice breeding. [ABSTRACT FROM AUTHOR]