Influence of Root Exudates and Soil on Attachment of <i>Pasteuria penetrans</i> to <i>Meloidogyne arenaria</i>

Liu, Chang; Timper, Patricia; Ji, Pingsheng; Mekete, Tesfamariam; Joseph, Soumi

doi:10.21307/jofnem-2017-076

Cited by 18 publications

(19 citation statements)

References 35 publications

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“…This result is in line with that obtained by Huang et al [18]; Olanrewaju et al [19]; Olahan et al [20]. Liu et al [21] also observed that root exudates have a greater effect on rhizosphere microbes in sandy loamy soil. The texture determines the drainage, aeration and the amount of water the soil can hold.…”

Section: Resultssupporting

confidence: 90%

Fungal Diversity in the Rhizosphere and Rhizoplane of Okra (Abelmoschus esculentus L.) Moench. in Nsukka, Enugu State, Nigeria

Onaebi

Okoro

Anyaogu

2020

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Aim: The growth and development of economically important crops are usually affected positively or negatively by the microbes present in the rhizosphere and rhizoplane. Based on this, the study was carried out to determine the fungal diversity in the rhizosphere and rhizoplane of okra plant. Methods: Okra seeds were purchased from an agricultural shop in Nsukka main market and were planted at Botanic garden, Department of Plant Science and Biotechnology, University of Nigeria, Nsukka. Physicochemical properties of the soil sample were evaluated prior to planting and as the plant aged. Rhizosphere and rhizoplane samples were collected at two weeks interval and dilution plate method was used in fungi isolation after which they were identified. The frequency of occurrence and the colony forming unit per gram of the sample (cfu/g) were evaluated. Results: The Physicochemical properties of the soil samples fluctuated as plant aged at two weeks intervals. The pH was slightly acidic to neutral which is ideal for most plant to grow. The water retention capacity, moisture content and organic matter content increased from 11.47-27.90 ml/g, 5.03-21.07% and 2.35-3.68% respectively at two weeks interval but fluctuates at subsequent weeks. A total of eleven (11) fungi were isolated from the rhizosphere and were identified as, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, Aspergillus bertholletius, Fusarium oxysporum, Galactomyces candidum, Helminthosporium solani, Rhizopus stolonifer, Mucor racemosus, Penicillium citrinum and Trichoderma viride. All fungi were present in the rhizoplane except Aspergillus bertholletius and Penicillium citrinum. Rhizosphere had a greater number of fungi than the rhizoplane. Aspergillus species were predominant in both the rhizosphere and rhizoplane. A. niger had the highest frequency of occurrence of 58.67% on the 6th week and 65.79% on the 4th week in rhizosphere and rhizoplane respectively. The colony forming unit (cfu/g) of Aspergillus niger was significantly different from all other isolates at P≤0.001 followed by Mucor racemosus and Fusarium oxysporum with significant differences at P≤0.05 and P≤0.01 respectively. Conclusion: The rhizosphere and rhizoplane of okra plants has been shown to be rich in fungal diversity and a greater number were obtained from the rhizosphere. The data obtained from this work could be exploited by microbial ecologist to ascertain ecological associations and biomass increase by the fungal communities which also forms part of ecosystem. The fungi had no pathological effect on the plant which suggest positive effect on the growth and development of okra plant as the plant aged.

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Section: Resultssupporting

confidence: 90%

Fungal Diversity in the Rhizosphere and Rhizoplane of Okra (Abelmoschus esculentus L.) Moench. in Nsukka, Enugu State, Nigeria

Onaebi

Okoro

Anyaogu

2020

ARRB

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“…(El-Borai et al, 2005). Some studies have shown that root exudates and some phytohormones, like indole-acetic acid, can alter the SC of PPN (Akhkha et al, 2002;Curtis, 2008) and affect the subsequent attachment of microorganisms to the nematode surface (Singh et al, 2014;Liu et al, 2017). Similarly, López de Mendoza et al (2000) recorded an increased uptake of the fluorescent lipid analog 5-N-(octadecanoyl) aminofluorescein (AF18) by the SC of J2 of M. incognita and the animal parasitic nematode Haemonchus contortus after exposure to tomato root exudates for 30 min.…”

Section: The Role Of the Nematode Surface Coat And Root Exudates In Pmentioning

confidence: 99%

“…Similarly, López de Mendoza et al (2000) recorded an increased uptake of the fluorescent lipid analog 5-N-(octadecanoyl) aminofluorescein (AF18) by the SC of J2 of M. incognita and the animal parasitic nematode Haemonchus contortus after exposure to tomato root exudates for 30 min. Root exudates from different plant species have a variable effect on attachment of endospores of P. penetrans to J2 of root-knot nematodes (Singh et al, 2014;Liu et al, 2017). This suggests that a correlation exists between the host type of root exudates and nematode-microbe interactions in soil.…”

Section: The Role Of the Nematode Surface Coat And Root Exudates In Pmentioning

confidence: 99%

Plants and Associated Soil Microbiota Cooperatively Suppress Plant-Parasitic Nematodes

2020

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Disease suppressive soils with specific suppression of soil-borne pathogens and parasites have been long studied and are most often of microbiological origin. As for the plant-parasitic nematodes (PPN), which represent a huge threat to agricultural crops and which successfully defy many conventional control methods, soil progression from conducive to suppressive state is accompanied by the enrichment of specific antagonistic microbial consortia. However, a few microbial groups have come to the fore in diminishing PPN in disease suppressive soils using culture-dependent methods. Studies with cultured strains resulted in understanding the mechanisms by which nematodes are antagonized by microorganisms. Recent culture-independent studies on the microbiome associated with soil, plant roots, and PPN contributed to a better understanding of the functional potential of disease suppressive microbial cohort. Plant root exudation is an important pathway determining host-microbe communication and plays a key role in selection and enrichment of a specific set of microbial antagonists in the rhizosphere as first line of defense against crop pathogens or parasites. Root exudates comprising primary metabolites such as amino acids, sugars, organic acids, and secondary metabolites can also cause modifications in the nematode surface and subsequently affect microbial attachment. A positive interaction between hosts and their beneficial root microbiota is correlated with a low nematode performance on the host. In this review, we first summarized the historical records of nematodesuppressive soils and then focused on more recent studies in this aspect, emphasizing the advances in studying nematode-microbe interactions over time. We highlighted nematode biocontrol mechanisms, especially parasitism, induced systemic resistance, and volatile organic compounds using microbial consortia, or bacterial strains of the genera Pasteuria, Bacillus, Pseudomonas, Rhizobium, Streptomyces, Arthrobacter, and Variovorax, or fungal isolates of Pochonia, Dactylella, Nematophthora, Purpureocillium, Trichoderma, Hirsutella, Arthrobotrys, and Mortierella. We discussed the importance of root exudates in plant communication with PPN and soil microorganisms, emphasizing their role in microbial attachment to the nematode surface and subsequent events of

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“…For example, endospore attachment varies with temperature, pH (Chen & Dickson, 1998), and plant root exudates (Liu, Timper, Ji, Mekete, & Joseph, 2017). In addition, replication rate of P. penetrans increases with temperature (Chen & Dickson, 1998;Lopes, Orr, & Blok, 2018).…”

Section: Natural Historymentioning

confidence: 99%

Rapid change in host specificity in a field population of the biological control organism Pasteuria penetrans

Liu

Gibson

Timper³

et al. 2018

Evolutionary Applications

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In biological control, populations of both the biological control agent and the pest have the potential to evolve and even to coevolve. This feature marks the most powerful and unpredictable aspect of biological control strategies. In particular, evolutionary change in host specificity of the biological control agent could increase or decrease its efficacy. Here, we tested for change in host specificity in a field population of the biological control organism Pasteuria penetrans . Pasteuria penetrans is an obligate parasite of the plant parasitic nematodes Meloidogyne spp., which are major agricultural pests. From 2013 through 2016, we collected yearly samples of P. penetrans from eight plots in a field infested with M. arenaria . Plots were planted either with peanut ( Arachis hypogaea ) or with a rotation of peanut and soybean ( Glycine max ). To detect temporal change in host specificity, we tested P. penetrans samples annually for their ability to attach to (and thereby infect) four clonal lines of M. arenaria . After controlling for temporal variation in parasite abundance, we found that P. penetrans from each of the eight plots showed temporal variation in their attachment specificity to the clonal host lines. The trajectories of change in host specificity were largely unique to each plot. This result suggests that local forces, at the level of individual plots, drive change in specificity. We hypothesize that coevolution with local M. arenaria hosts may be one such force. Lastly, we observed an overall reduction in attachment rate with samples from rotation plots relative to samples from peanut plots. This result may reflect lower abundance of P. penetrans under crop rotation, potentially due to suppressed density of host nematodes. As a whole, the results show local change in specificity on a yearly basis, consistent with evolution of a biological control organism in its ability to infect and suppress its target pest.

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Influence of Root Exudates and Soil on Attachment of Pasteuria penetrans to Meloidogyne arenaria

Cited by 18 publications

References 35 publications

Fungal Diversity in the Rhizosphere and Rhizoplane of Okra (Abelmoschus esculentus L.) Moench. in Nsukka, Enugu State, Nigeria

Fungal Diversity in the Rhizosphere and Rhizoplane of Okra (Abelmoschus esculentus L.) Moench. in Nsukka, Enugu State, Nigeria

Plants and Associated Soil Microbiota Cooperatively Suppress Plant-Parasitic Nematodes

Rapid change in host specificity in a field population of the biological control organism Pasteuria penetrans

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