scholarly journals A strain of an emerging Indian pathotype of Xanthomonas oryzae pv. oryzae defeats the rice bacterial blight resistance gene xa13 without inducing a clade III SWEET gene and is nearly identical to a recent Thai isolate

2018 ◽  
Author(s):  
Sara C. D. Carpenter ◽  
Prashant Mishra ◽  
Chandrika Ghoshal ◽  
Prasanta Dash ◽  
Li Wang ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Bacterial Blight ◽  
Xanthomonas Oryzae ◽  
Host Susceptibility ◽  
Transcription Activator ◽  
Rice Bacterial Blight ◽  
Indian Strain ◽  
Bacterial Blight Pathogen ◽  
Insight Into ◽  
S Genes

AbstractThe rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo) injects transcription activator-like effectors (TALEs) that bind and activate host ‘susceptibility’ (S) genes important for disease. Clade III SWEET genes are major S genes for bacterial blight. The resistance genes xa5, which reduces TALE activity generally, and xa13, a SWEET11 allele not recognized by the cognate TALE, have been effectively deployed. However, strains that defeat both resistance genes individually were recently reported in India and Thailand. To gain insight into the mechanism(s), we completely sequenced the genome of one such strain from each country and examined the encoded TALEs. Strikingly, the two strains are clones, sharing nearly identical TALE repertoires, including a TALE known to activate SWEET11 strongly enough to be effective even when diminished by xa5. We next investigated SWEET gene induction by the Indian strain. The Indian strain induced no clade III SWEET in plants harbouring xa13, indicating a pathogen adaptation that relieves dependence on these genes for susceptibility. The findings open a door to mechanistic understanding of the role SWEET genes play in susceptibility and illustrate the importance of complete genome sequence-based monitoring of Xoo populations in developing varieties with effective disease resistance.

Biological control of rice bacterial blight by plant-associated bacteria producing 2,4-diacetylphloroglucinol

2006 ◽  
Vol 52 (1) ◽  
pp. 56-65 ◽  
Author(s):  
Palaniyandi Velusamy ◽  
J Ebenezar Immanuel ◽  
Samuel S Gnanamanickam ◽  
Linda Thomashow
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Bacterial Blight ◽  
Field Experiments ◽  
Screening Method ◽  
Xanthomonas Oryzae ◽  
Rice Bacterial Blight ◽  
Fluorescent Pseudomonas ◽  
Tn5 Mutants ◽  
Bacterial Blight Pathogen

Certain plant-associated strains of fluorescent Pseudomonas spp. are known to produce the antimicrobial antibiotic 2,4-diacetylphloroglucinol (DAPG). It has antibacterial, antifungal, antiviral, and antihelminthic properties and has played a significant role in the biological control of tobacco, wheat, and sugar beet diseases. It has never been reported from India and has not been implicated in the biological suppression of a major disease of the rice crop. Here, we report that a subpopulation of 27 strains of plant-associated Pseudomonas fluorescens screened in a batch of 278 strains of fluorescent pseudomonads produced DAPG. The DAPG production was detected by a PCR-based screening method that used primers Phl2a and Phl2b and amplified a 745-bp fragment characteristic of DAPG. HPLC,1H NMR, and IR analyses provided further evidence for its production. We report also that this compound inhibited the growth of the devastating rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae in laboratory assays and suppressed rice bacterial blight up to 59%–64% in net-house and field experiments. Tn5 mutants defective in DAPG production (Phl–) of P. fluorescens PTB 9 were much less effective in their suppression of rice bacterial blight.Key words: biocontrol, 2,4-diacetylphloroglucinol, Pseudomonas fluorescens, rice, Xanthomonas oryzae pv. oryzae.

scholarly journals Cloning of the rice Xo1 resistance gene and interaction of the Xo1 protein with the defense-suppressing Xanthomonas effector Tal2h

2020 ◽  
Author(s):  
Andrew C. Read ◽  
Mathilde Hutin ◽  
Matthew J. Moscou ◽  
Fabio C. Rinaldi ◽  
Adam J. Bogdanove
Keyword(s):  
Resistance Gene ◽  
Resistance Genes ◽  
Bacterial Blight ◽  
Rice Variety ◽  
Susceptible Variety ◽  
Xanthomonas Oryzae ◽  
Physical Interaction ◽  
Bacterial Leaf Streak ◽  
Transcription Activator ◽  
Rice Leaves

AbstractThe Xo1 locus in the heirloom rice variety Carolina Gold Select confers resistance to bacterial leaf streak and bacterial blight, caused by Xanthomonas oryzae pvs. oryzicola and oryzae, respectively. Resistance is triggered by pathogen-delivered transcription activator-like effectors (TALEs) independent of their ability to activate transcription, and is suppressed by variants called truncTALEs common among Asian strains. By transformation of the susceptible variety Nipponbare, we show that one of 14 nucleotide-binding, leucine-rich repeat (NLR) protein genes at the locus, with a zfBED domain, is the Xo1 gene. Analyses of published transcriptomes revealed that the Xo1-mediated response is similar to those of NLR resistance genes Pia and Rxo1 and distinct from that associated with induction of the executor resistance gene Xa23, and that a truncTALE dampens or abolishes activation of defense-associated genes by Xo1. In Nicotiana benthamiana leaves, fluorescently-tagged Xo1 protein, like TALEs and truncTALEs, localized to the nucleus. And, endogenous Xo1 specifically co-immunoprecipitated from rice leaves with a pathogen-delivered, epitope-tagged truncTALE. These observations suggest that suppression of Xo1-function by truncTALEs occurs through direct or indirect physical interaction. They further suggest that effector co-immunoprecipitation may be effective for identifying or characterizing other resistance genes.

TALE-triggered and iTALE-suppressed Xa1 resistance to bacterial blight is independent of OsTFIIAγ1 or OsTFIIAγ5 in rice

2021 ◽  
Author(s):  
Xiameng Xu ◽  
Zhengyin Xu ◽  
Wenxiu Ma ◽  
Fazal Haq ◽  
Ying Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transgenic Plants ◽  
Expression Pattern ◽  
Bacterial Blight ◽  
Susceptibility Genes ◽  
Xanthomonas Oryzae ◽  
Transcription Activator ◽  
Rice Bacterial Blight ◽  
Unknown Factor ◽  
Biomolecular Fluorescence Complementation

Abstract Xa1-mediated resistance to rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is triggered by transcription activator-like effectors (TALEs) and suppressed by interfering TALEs (iTALEs). TALEs interact with the rice transcription factor OsTFIIAγ1 or OsTFIIAγ5 (Xa5) to transcriptionally activate expression of target resistance and/or susceptibility genes. However, it is not clear whether OsTFIIAγ is involved in TALE-triggered and iTALE-suppressed Xa1 resistance. In this study, genome-edited mutations in OsTFIIAγ5 or OsTFIIAγ1 of Xa1-containing rice IRBB1 and Xa1-transgenic plants of xa5-containing rice IRBB5 did not impair the activation or suppression of Xa1 resistance. Correspondingly, the expression pattern of Xa1 in mutated OsTFIIAγ5 and OsTFIIAγ1 rice lines and IRBB1 rice was similar. In contrast, the expression of OsSWEET11 was repressed in mutated OsTFIIAγ5 and OsTFIIAγ1 rice lines. Biomolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) showed that both the TALE PthXo1 and iTALE Tal3a interacted with OsTFIIAγ1 and OsTFIIAγ5 in plant nuclei. These results indicate that TALE-triggered and iTALE-suppressed Xa1 resistance to BB is independent of OsTFIIAγ1 or OsTFIIAγ5 in rice and suggest that an unknown factor is potentially involved in the interaction of Xa1, TALEs and iTALEs in rice.

scholarly journals Identification of Resistance Genes Effective Against Rice Bacterial Blight Pathogen in Eastern India

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 506-512 ◽  
Author(s):  
Marella Lalitha Shanti ◽  
M. L. C. George ◽  
C. M. Vera Cruz ◽  
M. A. Bernardo ◽  
R. J. Nelson ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Bacterial Blight ◽  
Blight Resistance ◽  
Bacterial Blight Resistance ◽  
Single Strain ◽  
Rice Bacterial Blight ◽  
Virulence Analysis ◽  
Bacterial Blight Pathogen ◽  
Polymerase Chain ◽  
Pathogen Populations

Breeding for bacterial blight resistance in rice requires an understanding of the contemporary pathogen populations in the locations where resistance genes are to be deployed. We characterized 450 strains of Xanthomonas oryzae pv. oryzae collected from three states of India using polymerase chain reaction fingerprinting and virulence analysis. This pathogen collection was differentiated into 17 haplotypes (12 lineages at 80% similarity level). Significant differences in the distribution of haplotypes were observed among regions. Virulence analysis of the pathogen collection revealed nine pathotypes. Among the populations from three regions, the Orissa population was the most diverse, consisting of 11 out of 17 haplotypes and five out of nine pathotypes detected in the total collection. Representative pathotypes were used to evaluate seven near-isogenic lines carrying individual bacterial blight resistance genes (Xa3, Xa4, xa5, Xa7, Xa10, xa13, and Xa21) and gene pyramids. Pathogen strains compatible to individual genes were present in detectable frequencies, although no single strain could overcome all resistance genes. Gene combinations Xa4 + xa5, xa5 + Xa21, and Xa4 + xa5 + Xa21 conferred a broad spectrum of resistance to all the strains evaluated, supporting the strategy of pyramiding appropriate resistance genes.

scholarly journals The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae

2016 ◽  
Vol 29 (3) ◽  
pp. 220-230 ◽  
Author(s):  
Xing-Yu Wang ◽  
Lian Zhou ◽  
Jun Yang ◽  
Guang-Hai Ji ◽  
Ya-Wen He
Keyword(s):  
Quorum Sensing ◽  
Bacterial Blight ◽  
Xanthomonas Campestris ◽  
Deletion Mutant ◽  
Extracellular Polysaccharide ◽  
Xanthomonas Oryzae ◽  
Rice Bacterial Blight ◽  
Double Deletion ◽  
Diffusible Signal Factor ◽  
Bacterial Blight Pathogen

Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

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