Phylogenetic position of the North American isolate of Pasteuria that parasitizes the soybean cyst nematode, Heterodera glycines, as inferred from 16S rDNA sequence analysis.

Abstract

A 1341 bp sequence of the 16S rDNA of an undescribed species of Pasteuria that parasitizes the soybean cyst nematode, Heterodera glycines, was determined and then compared with a homologous sequence of Pasteuria ramosa, a parasite of cladoceran water fleas of the family Daphnidae. The two Pasteuria sequences, which diverged from each other by a dissimilarity index of 7 %, also were compared with the 16S rDNA sequences of 30 other bacterial species to determine the phylogenetic position of the genus Pasteuria among the Gram-positive eubacteria. Phylogenetic analyses using maximumlikelihood, maximum-parsimony and neighbour-joining methods showed that the Heterodera glycines-infecting Pasteuria and its sister species, P. ramosa, form a distinct line of descent within the Alicyclobacillus group of the Bacillaceae. These results are consistent with the view that the genus Pasteuria is a deeply rooted member of the Clostridium-Bacillus-Streptococcus branch of the Gram-positive eubacteria, neither related to the actinomycetes nor closely related to true endospore-forming bacteria.Keywords : Heterodera glycines, Pasteuria sp., phylogeny, 16S rDNA sequence, soybean cyst nematode INTRODUCTIONPasteuria spp. are Gram-positive, mycelial and endospore-forming bacteria traditionally classified in the Actinomycetales (Sayre & Starr, 1989). Four species of Pasteuria have been described, the first of which, Pasteuria ramosa (the type species), parasitizes cladoceran water fleas of the family Daphnidae (Ebert et al., 1996 ;Metchnikoff, 1888 ;Sayre et al., 1979Sayre et al., , 1983. The other three species of Pasteuria are parasites of plantparasitic nematodes, against which they have shown great potential as biological control agents (Atibalentja et al., 1998 ; Brown et al., 1985 ; Chen et al., 1996 Chen et al., , 1997Duponnois & Ba, 1998 ;Giblin-Davis, 1990 ;Gowen et al., 1998 ;Nishizawa, 1987 ; WeibelzahlFulton et al., 1996). The three species of nematodeinfecting Pasteuria are as follows : Pasteuria penetrans, The GenBank accession number for the 16S rDNA sequence of the North American isolate of Pasteuria reported in this paper is AF134868.which occurs on root-knot nematodes, i.e. Meloidogyne spp. (Sayre & Starr, 1985 ; ; Pasteuria thornei, which affects root-lesion nematodes, i.e. Pratylenchus spp. ; and Pasteuria nishizawae, which is parasitic on cyst nematodes of the genera Heterodera and Globodera (Sayre et al., 1991a, b). Members of the genus Pasteuria are widespread and have been reported from 323 nematode species belonging to 116 genera including plantparasitic, entomopathogenic, predatory and free-living nematodes (Chen & Dickson, 1998 ;Ciancio et al., 1994 ;Sturhan, 1988).Attempts to culture Pasteuria spp. in vitro have not been successful (Bishop & Ellar, 1991 ;Williams et al., 1989). As a result, the taxonomy of the genus Pasteuria has been marked by a series of errors and confusion (Sayre & Starr, 1989), as it relies mainly on morphological, developmental and pathological characteristics including the size and s...

Detection and characterization of Pasteuria 16S rRNA gene sequences from nematodes and soils

“…3). All amplification products were initially verified by restriction digestion with either BamHI or StuI; 24 were sequenced (Table 1) and confirmed to be closely related to previously reported Pasteuria sequences (Anderson et al, 1999;Atibalentja et al, 2000).…”

“…Pasteuria endospore DNA was extracted as described by Atibalentja et al (2000). Soil and nematode DNA was isolated using an UltraClean soil DNA kit (MoBio) according to the manufacturer's instructions.…”

“…16S rRNA gene sequences were amplified with primers 27F or 39F, and 1388R (Anderson et al, 1999;Atibalentja et al, 2000;Lane, 1991). Primers 617F, 654R and …”

“…Use of 16S rRNA gene sequences to identify Pasteuria species and to assess the diversity of these bacteria within a nematode population or soil sample would be of great benefit in understanding nematode-parasite interactions and Pasteuria ecology. Development of 16S rRNA-based phylogeny and detection systems requires compilation of 16S rRNA gene sequences from a variety of representatives of the genus, yet only five 16S rRNA gene sequences for Pasteuria species could be retrieved from GenBank at the time of this study (Anderson et al, 1999;Atibalentja et al, 2000;Bekal et al, 2001;Ebert et al, 1996).…”

Characterization of Egyptian Fluorescent Rhizosphere Pseudomonad Isolates with High Nematicidal Activity against the Plant Parasitic Nematode Meloidogyne Incognita

“…Unfortunately, these fungi are usually unable to compete effectively with the resident soil microorganisms. Also fungal growth is slower than that of bacteria, so biological control by using bacteria is preferable [6,8]. The bacterium Pasteuria penetrans which is an obligate parasite, can control the spread of root knot nematodes in soil, but is difficult to grow under laboratory conditions and does not survive well in soil [9].…”