Twenty-one species belonging to ten genera of zoosporic fungi were recovered from 23 surface water samples collected from ponds of accumulated rainfall in the Riyadh region (Saudi Arabia) using sesame seeds as baits at 20 ± 2 C. The most common genera were Allomyces (3 species), Aqualinderella (I species), Dictyuchus (2 species) and Pythium (3 species). The remaining six genera were less freque...

The interaction between Trichoderma harzianum and the soilborne plant pathogen Pythium ultimum was studied by electron microscopy and further investigated by gold cytochemistry. Early contact between the two fungi was accompanied by the abnormal deposition of a cellulose-enriched material at sites of potential antagonist penetration. The antagonist displayed the ability to penetrate this barrie...

Sixteen streams in middle and eastern Tennessee were surveyed for the sudden oak-death pathogen Phytophthora ramorum 2010-2012. Surveys were conducted in the spring and fall using healthy Rhododendron leaves, and a total of 354 oomycete isolates were recovered. Sequence analysis of the ITS region provisionally identified 151 Phytophthora, 200 Pythium, two Halophytophthora and one Phytopythium. ...

A new species of Pythium collected from grapevine roots (Vitis vinifera) in South Africa and roots of common beet (Beta vulgaris) in Majorca, Spain, is described. The phylogenetic position of the new species was investigated by multigene sequence analyses of the internal transcribed spacers (ITS1 and ITS2) of the rDNA region, as well as three other nuclear and three mitochondrial coding genes. ...

A new species of Pythium isolated from wheat and apple roots in eastern Washington is described. Pythium abappressorium sp. nov. is characterized by abundant appressoria. Plerotic oospores and sporangia are formed from the appressoria and remnants of the appressoria remain attached to the base of sporangia at maturity. Smaller appressorial swellings, reminiscent of hyphal swellings, are also fo...

Pythium species were isolated from diseased samples of creeping bentgrass and annual bluegrass. Among fourteen isolates from decayed roots and crowns, seven were P. graminicola, five were P. torulosum and two were P. ultimum. These species were identified by comparison of cultural and morphological characteristics to literature and reference isolates. In a tissue culture plate assay for quantif...

Plants can influence the soil they grow in, and via these changes in the soil they can positively or negatively influence other plants that grow later in this soil, a phenomenon called plant-soil feedback. A fascinating possibility is then to apply positive plant-soil feedback effects in sustainable agriculture to promote plant growth and resistance to pathogens. We grew the cut flower chrysant...

The plant growth-promoting rhizobacterium Pseudomonas aeruginosa 7NSK2 produces three siderophores when iron is limited: the yellow-green fluorescent pyoverdin, the salicylate derivative pyochelin, and salicylic acid. This Pseudomonas strain was shown to be an efficient antagonist of Pythium-induced damping-off. The role of pyoverdin and pyochelin in the suppression of Pythium splendens was inv...

Carbohydrate-active enzymes (CAZymes) are involved in the metabolism of glycoconjugates, oligosaccharides, and polysaccharides and, in the case of plant pathogens, in the degradation of the host cell wall and storage compounds. We performed an in silico analysis of CAZymes predicted from the genomes of seven Pythium species (Py. aphanidermatum, Py. arrhenomanes, Py. irregulare, Py. iwayamai, Py...

Stenotrophomonas maltophilia W81 can protect sugar beet against PYTHIUM:-mediated damping-off disease through the production of an extracellular protease. Here, the proteolytic enzyme of W81 was purified by anion-exchange chromatography and characterized as a serine protease. The purified enzyme was fungicidal against PYTHIUM: ultimum in vitro. Its synthesis was inducible by casein in W81, and ...