<i>Pantoea stewartii</i> subsp. <i>stewartii</i>: lessons learned from a xylem‐dwelling pathogen of sweet corn

Roper, M. Caroline

doi:10.1111/j.1364-3703.2010.00698.x

Cited by 112 publications

(135 citation statements)

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“…In the fine-mapping populations, 194, 80, and 146 homozygous recombinants were screened for NLB in 2010, 2011, and 2012, respectively. Lines carrying mutations in the genes pan1 and pan2 were tested in Aurora, New York in 2011and in Ithaca, New York in 2011. Plants were inoculated with S. turcica isolate StNY001 (race 1), using previously described inoculation procedures (Chung et al 2010a).…”

Section: Disease Trialsmentioning

confidence: 99%

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Unraveling Genomic Complexity at a Quantitative Disease Resistance Locus in Maize

et al. 2014

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Multiple disease resistance has important implications for plant fitness, given the selection pressure that many pathogens exert directly on natural plant populations and indirectly via crop improvement programs. Evidence of a locus conditioning resistance to multiple pathogens was found in bin 1.06 of the maize genome with the allele from inbred line "Tx303" conditioning quantitative resistance to northern leaf blight (NLB) and qualitative resistance to Stewart's wilt. To dissect the genetic basis of resistance in this region and to refine candidate gene hypotheses, we mapped resistance to the two diseases. Both resistance phenotypes were localized to overlapping regions, with the Stewart's wilt interval refined to a 95.9-kb segment containing three genes and the NLB interval to a 3.60-Mb segment containing 117 genes. Regions of the introgression showed little to no recombination, suggesting structural differences between the inbred lines Tx303 and "B73," the parents of the fine-mapping population. We examined copy number variation across the region using next-generation sequencing data, and found large variation in read depth in Tx303 across the region relative to the reference genome of B73. In the fine-mapping region, association mapping for NLB implicated candidate genes, including a putative zinc finger and pan1. We tested mutant alleles and found that pan1 is a susceptibility gene for NLB and Stewart's wilt. Our data strongly suggest that structural variation plays an important role in resistance conditioned by this region, and pan1, a gene conditioning susceptibility for NLB, may underlie the QTL.T HE genes and loci that influence host-pathogen interactions vary in allele effects, specificities, and linkage relationships. While disease resistance can be conditioned by single genes with large effect (Bent 1996;Jones and Dangl 2006), the emerging model of resistance for many plant diseases is complex in nature, with many genes and loci functioning in concert and each contributing a small proportion of the total phenotypic variation Poland et al. 2011;Cook et al. 2012b). Each locus has a unique profile, with some loci contributing broadspectrum protection against diverse pathogen species and strains. Investigating these intricacies offers the opportunity to understand the diverse ways in which plants defend themselves against microbial assault.Correlated responses to multiple diseases have been observed in various germplasm panels, implying that there are loci and genes that condition broad-spectrum resistance (Rossi et al. 2006;Gurung et al. 2009;Wisser et al. 2011). At the chromosomal segment level, disease and insect resistance loci colocalize in a nonrandom fashion (McMullen and Simcox 1995;Williams 2003;Wisser et al. 2005) and loci have been identified that confer resistance to diverse pathogen isolates and taxa (Zwonitzer et al. 2010;Chung et al. 2011;Belcher et al. 2012). There is evidence to suggest that gene clusters can confer resistance to more than one disease. A cluster of germin-like ...

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Section: Disease Trialsmentioning

confidence: 99%

“…Both pathogens spread through the vascular tissue, causing wilted lesions by plugging xylem vessels (Jennings and Ullstrup 1957;Roper 2011). The importance of genes localized to maize bin 1.06 in resistance to both NLB and Stewart's wilt has been described in multiple mapping populations.…”

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Unraveling Genomic Complexity at a Quantitative Disease Resistance Locus in Maize

et al. 2014

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“…Considering that 1 g of soil may harbor 10 3 -10 6 bacterial species (Torsvik et al, 1990;Curtis et al, 2002;Gans et al, 2005;Roesch et al, 2007), the vast majority would remain undetected. Community richness estimations in fact indicated that most of the diversity in the environment is due to rare members (Hughes et al, 2001;Reeder and Knight, 2009) and these may also have important ecological functions, for example, in cycling of elements, as a supplier of phytohormones or as phytopathogens (Karadeniz et al, 2006;Humbert et al, 2010;Pester et al, 2010;Roper, 2011;Krzmarzick et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

et al. 2012

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Ribosomal 16S rRNA gene pyrosequencing was used to explore whether the genetically modified (GM) Bt-maize hybrid MON 89034 × MON 88017, expressing three insecticidal recombinant Cry proteins of Bacillus thuringiensis, would alter the rhizosphere bacterial community. Fine roots of field cultivated Bt-maize and three conventional maize varieties were analyzed together with coarse roots of the Bt-maize. A total of 547 000 sequences were obtained. Library coverage was 100% at the phylum and 99.8% at the genus rank. Although cluster analyses based on relative abundances indicated no differences at higher taxonomic ranks, genera abundances pointed to variety specific differences. Genera-based clustering depended solely on the 49 most dominant genera while the remaining 461 rare genera followed a different selection. A total of 91 genera responded significantly to the different root environments. As a benefit of pyrosequencing, 79 responsive genera were identified that might have been overlooked with conventional cloning sequencing approaches owing to their rareness. There was no indication of bacterial alterations in the rhizosphere of the Bt-maize beyond differences found between conventional varieties. B. thuringiensis-like phylotypes were present at low abundance (0.1% of Bacteria) suggesting possible occurrence of natural Cry proteins in the rhizospheres. Although some genera indicated potential phytopathogenic bacteria in the rhizosphere, their abundances were not significantly different between conventional varieties and Bt-maize. With an unprecedented sensitivity this study indicates that the rhizosphere bacterial community of a GM maize did not respond abnormally to the presence of three insecticidal proteins in the root tissue.

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“…P. stewartii also possesses a hrp and wts gene cluster encoding a Hrp type III secretion system and effector proteins (8). Affected seedlings wither (wilt phase), and affected mature plants develop necrotic lesions (leaf blight phase), leading to losses in the crop yield (9). Other pathogenic Pantoea species include Pantoea ananatis, which causes soft rot of onions (10), and Pantoea citrea, which causes pink disease of pineapple (11).…”

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confidence: 99%

Proteomic Analysis of the Quorum-Sensing Regulon in Pantoea stewartii and Identification of Direct Targets of EsaR

Ramachandran

Stevens

2013

Appl Environ Microbiol

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The proteobacterium Pantoea stewartii subsp. stewartii causes Stewart's wilt disease in maize when it colonizes the xylem and secretes large amounts of stewartan, an exopolysaccharide. The success of disease pathogenesis lies in the timing of bacterial virulence factor expression through the different stages of infection. Regulation is achieved through a quorum-sensing (QS) system consisting of the acyl-homoserine lactone (AHL) synthase, EsaI, and the transcription regulator EsaR. At low cell densities, EsaR represses transcription of itself and of rcsA, an activator of the stewartan biosynthesis operon; it also activates esaS, which encodes a small RNA (sRNA). Repression or activation ceases at high cell densities when EsaI synthesizes sufficient levels of the AHL ligand N-3-oxo-hexanoyl-L-homoserine lactone to bind and inactivate EsaR. This study aims to identify other genes activated or repressed by EsaR during the QS response. Proteomic analysis identified a QS regulon of more than 30 proteins. Electrophoretic mobility shift assays of promoters of genes encoding differentially expressed proteins distinguished direct targets of EsaR from indirect targets. Additional quantitative reverse transcription-PCR (qRT-PCR) and DNA footprinting analysis established that EsaR directly regulates the promoters of dkgA, glpF, and lrhA. The proteins encoded by dkgA, glpF, and lrhA are a 2,5-diketogluconate reductase, glycerol facilitator, and transcriptional regulator of chemotaxis and motility, respectively, indicating a more global QS response in P. stewartii than previously recognized.

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Pantoea stewartii subsp. stewartii: lessons learned from a xylem‐dwelling pathogen of sweet corn

Abstract: http://www.apsnet.org/publications/apsnetfeatures/Pages/StewartsWilt.aspx.

Cited by 112 publications

References 50 publications

Unraveling Genomic Complexity at a Quantitative Disease Resistance Locus in Maize

Unraveling Genomic Complexity at a Quantitative Disease Resistance Locus in Maize

Importance of rare taxa for bacterial diversity in the rhizosphere of Bt- and conventional maize varieties

Proteomic Analysis of the Quorum-Sensing Regulon in Pantoea stewartii and Identification of Direct Targets of EsaR

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