Studies on the potential use of Pasteuria penetrans as a biocontrol agent of root‐knot nematodes (Meloidogyne spp.)

Abstract

Some aspects of the interaction of the bacterial parasite Pasteuria penetrans and the root-knot nematode (Meloidogyne spp.) were investigated in laboratory and pot experiments. The variable spore attachment on juveniles exposed to water suspensions of the bacterium is probably attributed to differential susceptibility of biotypes within a heterogeneous Meloidogyne population. The relationship between spore concentration and attachment level is not linear over a range of spore dosages, indicating that even at very high spore concentrations the number of spores capable of attachment may not be present in excess and it is difficult to ensure sufficient numbers of spores to ensure infection will attach to all nematodes. Attempts to apply the bacterium in conditions such as might occur in seedbeds did not suppress nematode multiplication after transplanting in nematode-infested soil, indicating that the only effective application method is a thorough spore distribution in the planting sites. Two major constraints were revealed: high levels of spore attachment to juveniles does not always guarantee a significant reduction of egg laying and this is greatly influenced by the Meloidogyne biotype. Furthermore, the cumulative effect of the parasite in reducing Meloidogyne populations over several crop cycles was less than expected as the bacterium reduced intra-specific competition for the food supply and the less damaged root enabled many nematodes to survive.

The effect of different initial densities of nematode (Meloidogyne javanica) on the build-up of Pasteuria penetrans population

“…The findings of Tzortzakakis et al(1997) support these results that the number of egg masses were higher where there had been a lower initial nematode density. In the first crop untreated control plants of the higher nematode inoculum densities senesced prematurely due to the debilitating effects of the heavy nematode burden and were harvested after 8 weeks.…”

Multiple-strand displacement and identification of single nucleotide polymorphisms as markers of genotypic variation of Pasteuria penetrans biotypes infecting root-knot nematodes

“…(Ebert, 1994;Anderson et al, 1999;Atibalentja et al, 2000;Giblin-Davis et al, 2003). As naturally occurring parasites of phytopathogenic nematodes, species of Pasteuria are attractive candidates for the biocontrol of destructive pathogens that infect numerous important crop plants (Brown, 1985;Giblin-Davis, 1990;Tzortzakakis et al, 1997;Chen & Dickson, 1998). Demonstrations of the suppression of Meloidogyne spp.…”

Detection of Pasteuria penetrans infection in Meloidogyne arenaria race 1 in planta by polymerase chain reaction

“…In all hosts, they proceed through a developmental growth phase that includes a mycelial-like stage followed by the formation of tetrad and diad clusters of cells, before differentiation into phases associated with endospore formation. Pasteuria penetrans is an obligate parasite of root-knot nematodes, Meloidogyne spp., and has emerged as a promising biocontrol agent for this ubiquitous and destructive crop pest [8][9][10][11][12]. Phylogenetic analysis using the 16S rDNA gene finds Pasteuria spp.…”

“…[2][3][4][5][6][7]. Pasteuria penetrans is an obligate parasite of root-knot nematodes, Meloidogyne spp., and has emerged as a promising biocontrol agent for this ubiquitous and destructive crop pest [8][9][10][11][12]. The effect of P. penetrans in reducing Meloidogyne spp.…”