Microbial Communities in Globodera pallida Females Raised in Potato Monoculture Soil

Abstract

Globodera spp. are under strict quarantine in many countries. Suppressiveness to cyst nematodes can evolve under monoculture of susceptible hosts. Females developing in potato monoculture soil infested with G. pallida populations Chavornay or Delmsen were examined for inherent microbial communities. In the greenhouse, nonheated and heat-treated (134°C for 10 min) portions of this soil were placed in root observation chambers, planted with Solanum tuberosum 'Selma', and inoculated with G. pallida Pa3 Chavornay. At harvest in Delmsen soil, cysts had fewer eggs in nonheated than heat-treated soil. In denaturing gradient gel electrophoresis analysis, bacterial and fungal fingerprints were characterized by a high variability between replicates; nonheated soils displayed more dominant bands than heated soils, indicating more bacterial and fungal populations. In amplicon pyrosequencing, females from nonheated portions frequently contained internal transcribed spacer sequences of the fungus Malassezia. Specific for the Chavornay and Delmsen population, ribosomal sequences of the bacteria Burkolderia and Ralstonia were abundant on eggs. In this first report of microbial communities in G. pallida raised in potato monoculture, candidate microorganisms perhaps associated with the health status of the eggs of G. pallida were identified. If pathologies on cyst nematodes can be ascertained, these organisms could improve the sustainability of production systems.

Plants and Associated Soil Microbiota Cooperatively Suppress Plant-Parasitic Nematodes

“…The decline of PPN populations in field soils was first reported in 1962 by Collingwood for the cyst nematode Heterodera avenae in the United Kingdom under intensive cropping of cereal hosts (Collingwood, 1962;Kerry, 1982). Since then, suppressive soils have been reported for several nematode species including H. avenae in the United Kingdom (Gair et al, 1969;Williams, 1969;Kerry, 1975), Heterodera schachtii in Netherlands, United Kingdom, and United States (Heijbroek, 1983;Crump and Kerry, 1987;Westphal and Becker, 1999), Globodera rostochiensis in Germany (Roessner, 1987), Globodera pallida in the United Kingdom and Germany (Crump and Flynn, 1995;Eberlein et al, 2016), Heterodera glycines in the United States and China (Chen et al, 1996b;Sun and Liu, 2000;Hamid et al, 2017;Hussain et al, 2018), the false root-knot nematode Nacobbus aberrans in Mexico (Zuckerman et al, 1989), root-knot nematodes Meloidogyne spp. in Mexico, United States, Spain, and Germany (Bird and Brisbane, 1988;Zuckerman et al, 1989;Chen et al, 1994b;Pyrowolakis et al, 2002; FIGURE 1 | Microbial antagonists of plant-parasitic nematodes and mechanisms of their antagonism.…”

“…It was suggested that the application of formalin inhibited the parasitic fungi Nematophthora gynophila and Pochonia chlamydosporia and thereby resulted in an increased population density of H. avenae (Kerry et al, 1980;Kerry, 1988). Later, several studies demonstrated the microbial involvement in soil suppressiveness by soil autoclaving or heating (Bird and Brisbane, 1988;Zuckerman et al, 1989;Kluepfel et al, 1993;Chen et al, 1996b;Weibelzahl-Fulton et al, 1996;Westphal and Becker, 1999;Sun and Liu, 2000;Bent et al, 2008;Adam et al, 2014b;Eberlein et al, 2016;Giné et al, 2016;Hamid et al, 2017;Bhuiyan et al, 2018), by the application of biocides (Kerry et al, 1980;Crump and Kerry, 1987;Westphal and Becker, 1999;Sun and Liu, 2000;Westphal and Becker, 2001;Pyrowolakis et al, 2002;Yin et al, 2003a,b;Bent et al, 2008;Song et al, 2017), and through soil transplantation (Mankau, 1975;Stirling and Kerry, 1983;Kluepfel et al, 1993;Westphal and Becker, 2000;Sun and Liu, 2000;Yin et al, 2003a,b;Chen, 2007;Bent et al, 2008). Notably, the soil suppressiveness was also observed to be transferred by egg-suspensions of the root-knot nematode Meloidogyne incognita (Orion et al, 2001) and cysts of the sugar beet cyst nematode H. schachtii (Westphal and Becker, 2001).…”

“…Antagonistic effects of diverse microorganisms were detected in in vitro studies on the biology of free-living nematodes (Huang et al, 2005;Rae et al, 2008), or they appeared as by-products of studies on soil suppressiveness against other pathogens and parasites of plants (Adam et al, 2014a). Nevertheless, there are still numerous microbial species that were isolated from nematodes in suppressive soils (Bird and Brisbane, 1988;Chen et al, 1996a;Weibelzahl-Fulton et al, 1996;Borneman et al, 2004;Borneman and Becker, 2007;Chen, 2007;Adam et al, 2014b;Eberlein et al, 2016;Giné et al, 2013Giné et al, , 2016. In this review we focused on the microorganisms associated with the most important group of PPN, sedentary endoparasites (root-knot and cyst nematodes).…”

“…P. cucumerina was also isolated from the egg masses of M. incognita (Yu and Coosemans, 1998) and eggs of G. pallida (Kooliyottil et al, 2017), and has been found to infect eggs of G. rostochiensis (Atkins et al, 2003). The microbial community analysis using bacterial 16S rRNA gene and ITS amplicon sequencing from G. pallida females showed a dominance of diverse microbiota such as Burkholderia, Bosea, Rhizobium, Devosia, Ralstonia, and Streptomyces, and the fungal genera Davidiella, Hirsutella, Malassezia, Microdochium, Monographella, and Penicillium in potato monoculture soil (Eberlein et al, 2016). Some of the bacterial genera have been previously associated with infective stages of root-knot and lesion nematodes in suppressive soils (Adam et al, 2014b;Elhady et al, 2017).…”

Prospecting fungal parasites of the potato cyst nematode Globodera pallida using a rapid screening technique

“…Chaetomium globosum Kunze was isolated from the eggs of Heterodera glycines and this fungus was found to reduce hatching in laboratory conditions. In a culture independent study of soil suppressive to G. pallida , Microdochium bolleyi (Sprauge) along with several other fungi were reported .…”