title: A new species of Pythium with ornamented oogonia: morphology, taxonomy, internal transcribed spacer region of its ribosomal RNA, and its comparison with related species.
abstract: Pythium spiculum sp. nov. was isolated from soil samples taken in a vineyard in the Burgundian region of France and from different locations in Spain and Portugal. The oomycete has spiny oogonia and does not sporulate readily. It resembles Pythium mamillatum Meurs, but has its own distinguishing characteristics. It also exhibits sickle-shaped as well as spherical appressoria which at times are associated with sex organs like those found in Pythium abappressorium Paulitz and Pythium contiguanum Paul. Sequencing of the internal transcribed spacer region of its nuclear ribosomal DNA and a close look at its morphological characters have now enabled us to describe it as a new species. The internal transcribed spacer region of its rRNA gene sequence is comprised of 945 bases. This oomycete is closely related to the members that form ornamented or spiny oogonia like Pythiummamillatum, Pythium spinosum and Pythium irregulare but also with those producing smooth-walled oogonia like Pythium paroecandrum, Pythium sylvaticum and Pythium cylindrosporum. Taxonomic description of this new species, its comparison with related oomycetes, the sequence of the internal transcribed spacer region of its rRNA gene and the phylogenetic tree, are given here.
authors.affiliation: Laboratoire des Sciences de la Vigne, Institut Jules Guyot, Université de Bourgogne, Dijon, France. bernard.paul@u-bourgogne.fr
authors.forename: Bernard
authors.initials: B
authors.lastname: Paul
authors.forename: Kanak
authors.initials: K
authors.lastname: Bala
authors.forename: Belbahri
authors.initials: B
authors.lastname: Lassaad
authors.forename: Gautier
authors.initials: G
authors.lastname: Calmin
authors.forename: Esperanza
authors.initials: E
authors.lastname: Sanchez-Hernandez
authors.forename: Francois
authors.initials: F
authors.lastname: Lefort
mesh_terms: D001483:Base Sequence; D004275:DNA, Ribosomal / Q000032:analysis; D021903:DNA, Ribosomal Spacer / Q000032:analysis*; D005602:France; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D010802:Phylogeny; D011775:Pythium / Q000145:classification* / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D012335:RNA, Ribosomal / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013030:Spain
chemical_list: D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D012335:RNA, Ribosomal