Abstract
The bacterium Pasteuria penetrans is a parasite of root-knot nematodes (Meloidogyne spp.). Endospores of P. penetrans attach to the cuticle of second-stage juveniles (J2) and subsequently sterilize infected females. When encumbered by large numbers of spores, juveniles are less mobile and their ability to infect roots is reduced. This study looked at different factors that influence spore attachment of P. penetrans to the root-knot nematode Meloidogyne arenaria. Pretreatment of J2 with root exudates of eggplant (Solanum melongena cv. Black beauty) reduced spore attachment compared with pretreatment with phosphate-buffered saline (PBS), suggesting that the nematode surface coat was altered or the spore recognition domains on the nematode surface were blocked. Spore attachment was equally reduced following exposure to root exudates from both host and nonhost plants for M. arenaria, indicating a common signal that affects spore attachment. Although phytohormones have been shown to influence the lipophilicity of the nematode surface coat, auxins and kinetins did not affect spore attachment compared with PBS. Root exudates reduced spore attachment more in sterilized soil than in natural soil. Sterilization may have eliminated microbes that consume root exudates, or altered the chemical components of the soil solution or root exudates. Root exudates caused a greater decrease in spore attachment in loamy sand than in a sandy loam soil. The sandy loam had higher clay content than the loamy sand, which may have resulted in more adsorption of compounds in the root exudates that affect spore attachment. The components of the root exudates could have also been modified by soil type. The results of this study demonstrate that root exudates can decrease the attachment of P. penetrans endospores to root-knot nematodes, indicating that when these nematodes enter the root zone their susceptibility to spore attachment may decrease.
Highlights
The bacterium Pasteuria penetrans is a parasite of root-knot nematodes (Meloidogyne spp.)
The J2 treated with root exudates and the detergent had lower (P, 0.0001) spore attachment than those treated with phosphate-buffered saline (PBS) (Fig. 1)
Incubating J2 in root exudates or detergent reduced spore attachment by 80% to 95% in Trial 1, and 76% to 84% in Trial 2 compared with J2 incubated in PBS
Summary
The bacterium Pasteuria penetrans is a parasite of root-knot nematodes (Meloidogyne spp.). This study looked at different factors that influence spore attachment of P. penetrans to the root-knot nematode Meloidogyne arenaria. Phytohormones have been shown to influence the lipophilicity of the nematode surface coat, auxins and kinetins did not affect spore attachment compared with PBS. When J2 were pretreated with lectin or carbohydrates that can bind to the nematode surface coat, fewer spores attached to the J2 (Spiegel et al, 1996), suggesting a carbohydrate-protein mechanism for spore attachment. Root exudates have been shown to alter the surface coat of plant-parasitic nematodes (Curtis, 2008); Influence of Root Exudates on Attachment of Pasteuria penetrans: Liu et al 305 no studies have evaluated the effect of exudates on attachment of P. penetrans spores to the surface coat of root-knot nematodes. The objective of this study was to investigate the influence of root exudates on the attachment of P. penetrans to root-knot nematodes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
