Browsing by Subject "Xanthomonas"
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Item Isolation frequency of xanthomonas axonopodis pv. malvacearum from acid delinted and easiflo treated cotton seed(2009-08) Alexander, Aaron S.; Woodward, Jason E.; Boman, Randal K.This project was conducted to determine if an alternative method of delinting cotton seed based on mechanical delinting and use of the Easiflo seed coating process, would be comparable to the current standard method of acid delinting seed in the frequency of survival of Xanthomonas axonopodis pv. malvacearum (Xam). Paymaster 2326 RR was grown at Halfway, TX in 2006 and treated with a solution of Xam + Silwet L77. In 2007, cotton bolls from Paymaster 2326RR and All-Tex Xpress RR were injected with concentrations of Xam. In 2007, bulk harvested seed from a third cultivar (Deltapine 164B2RF) was obtained from a field that had been naturally infected with Xam. Seed from each infection method and cultivar was divided into two batches, with one batch mechanically delinted and treated with Easiflo coating and the other batch processed with acid delinting. For each batch, isolations were made on 1,000 seed (900 in Paymaster 2326 RR from 2006) and yellow, mucoid colonies characerisitc of Xam were stored and later tested for pathogenicity on cotton seedlings. In 2006, Paymaster 2326RR (inoculated by sprays on leaves) had a higher frequency of Xam using Easiflo treatment (2.7%) than with the acid treatment (0%). In 2007, All-Tex Xpress RR (boll injection) had a higher frequency of Xam recovered from seed with acid delinted seed (3.8%) than with the Easiflo treatment (1.1%); however, isolation frequencies were similar for Paymaster 2326 RR. No differences in Xam isolation frequency were observed between the two methods for naturally infested seed. Overall, results from this study are inconclusive, thus, additional studies are required to better understand the impact of using the Easiflo seed coating system on Bacterial blight development.Item Novel Virulent Phages for Xylella fastidiosa and Other Members of the Xanthomonadaceae(2013-08-27) Ahern, Stephen JThe xylem-limited bacterium, Xylella fastidiosa, is the causal agent of several plant diseases, most notably Pierce?s Disease of grapes and citrus variegated chlorosis. We report on the isolation and characterization of the first virulent phages for X. fastidiosa, Xfas103, Xfas106, Xfas303, Xfas304, with host ranges extending to Xanthomonas. Efficiency of plating on X. fastidiosa strain Temecula or Xanthomonas strain EC-12 ranged from 1.41 x 10^(-1) to 2.29 x 10^(-3) , depending on propagating and plating host. Phages propagated on homologous hosts had an observed adsorption rate constant of (4.33 ? 0.28) x 10^(-12) ml cell^(-1) min^(-1) for strain Temecula, and ranged from (4.58 ? 0.30) x 10^(-10) to (7.26 ? 0.42) x 10^(-10) ml cell^(-1) min^(-1) for strain EC-12. Siphophages Xfas103 and Xfas106 exhibit over 80% nucleotide identity to each other and are syntenic to phage BcepNazgul. Here it is proposed that phage BcepNazgul is the founding member of a novel phage type, to which Xfas103 and Xfas106 belong. Podophages Xfas303 and Xfas304 show no significant DNA homology, both encode for a single subunit RNA polymerase at the right end of the class II gene cluster, and are new members of the phiKMV-like phage type. The four phages utilize Type IV pili as receptors to infect strains Temecula and EC-12. The phages may be useful as agents for an effective and environmentally friendly strategy for the control of diseases caused by X. fastidiosa.