Authors
S. L.
Thomas
and
P.
Bonello
,
Department of Plant Pathology, The Ohio State University, Columbus 43210
;
P. E.
Lipps
,
Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691
; and
M. J.
Boehm
,
Department of Plant Pathology, The Ohio State University, Columbus
ABSTRACT
Avenacinase activity has been shown to be a key factor determining the host range of Gaeumannomyces graminis on oats (Avena sativa). G. graminis var. avenae produces avenacinase, which detoxifies the oat root saponin avenacin, enabling it to infect oats. G. graminis var. tritici does not produce avenacinase and is unable to infect oats. G. graminis var. avenae is also reported to incite take-all patch on creeping bentgrass (Agrostis stolonifera). It is unknown whether creeping bentgrass produces avenacin and if the avenacin-avenacinase interaction influences G. graminis pathogenicity on creeping bentgrass. The root extracts of six creeping bentgrass cultivars were analyzed by fluorimetry, thin-layer chromatography, and high performance liquid chromatography for avenacin content. Avenacin was not detected in any creeping bentgrass cultivars, and pathogenicity assays confirmed that both G. graminis var. avenae and G. graminis var. tritici can infect creeping bentgrass and wheat (Triticum aestivum), but only G. graminis var. avenae incited disease on oats. These results are consistent with the root analyses and confirm that avenacinase activity is not required for creeping bentgrass infection by G. graminis.
