1887

Abstract

The phytopathogen pv. glycinea produces the exopolysaccharide (EPS) alginate, which is thought to function in epiphytic fitness and virulence. A key regulator for alginate biosynthesis in and is the alternative sigma factor AlgT ( ). In this study, the contribution of alginate synthesis and AlgT to epiphytic fitness and virulence of was examined. Alginate biosynthesis mutants were generated for the pv. glycinea strains PG4180 and PG4180.muc, representing a comprehensive set of alginate- and AlgT-positive or -negative derivatives. Analysis of and phenotypes revealed that AlgT strongly promoted growth, survival and symptom development, but decreased the ability to grow . In contrast, alginate biosynthesis had only marginal impact. Quantitative and gene expression analyses for alginate biosynthesis and were carried out at two temperatures in AlgT-negative and -positive backgrounds. as well as gene expression was AlgT-dependent, plant-inducible and temperature-dependent, with higher expression at 18 compared to 28 °C; however, no temperature dependence was observed . Our data suggest that AlgT may act as a global regulator for virulence and fitness traits of independent of its role in EPS biosynthesis.

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2008-02-01
2019-10-19
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