Publications by authors named "Mary K Musyoki"

3 Publications

  • Page 1 of 1

Proliferation of the biocontrol agent f. sp. and its impact on indigenous rhizosphere fungal communities in maize under different agro-ecologies.

Rhizosphere 2016 Jun;1:17-25

Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany.

Our objectives were to (1) monitor the proliferation of the biocontrol agent (BCA) f. sp. strain "Foxy-2", an effective soil-borne BCA against the parasitic weed , in the rhizosphere of maize under different agro-ecologies, and (2) investigate its impact on indigenous rhizosphere fungal community abundance and composition. Field experiments were conducted in Busia and Homa Bay districts in western Kenya during two cropping seasons to account for effects of soil type, climate, growth stage and seasonality. Maize seeds were coated with or without "Foxy-2" and soils were artificially infested with seeds. One treatment with nitrogen rich organic residues () was established to compensate hypothesized resource competition between "Foxy-2" and the indigenous fungal community. Rhizosphere soil samples collected at three growth stages (i.e., EC30, EC60, EC90) of maize were subjected to abundance measurement of "Foxy-2" and total indigenous fungi using quantitative polymerase chain reaction (qPCR) analysis. Terminal restriction fragment length polymorphism (TRFLP) analysis was used to assess potential alterations in the fungal community composition in response to "Foxy-2" presence. "Foxy-2" proliferated stronger in the soils with a sandy clay texture (Busia) than in those with a loamy sand texture (Homa Bay) and revealed slightly higher abundance in the second season. "Foxy-2" had, however, only a transient suppressive effect on total indigenous fungal abundance which ceased in the second season and was further markedly compensated after addition of residues. Likewise, community structure of the indigenous fungal community was mainly altered by maize growth stages, but not by "Foxy-2". In conclusion, no adverse effects of "Foxy-2" inoculation on indigenous fungal rhizosphere communities were observed corroborating the safety of this BCA under the given agro-ecologies.
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http://dx.doi.org/10.1016/j.rhisph.2016.06.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5125437PMC
June 2016

Biocontrol agent f.sp. has no adverse effect on indigenous total fungal communities and specific AMF taxa in contrasting maize rhizospheres.

Fungal Ecol 2016 Oct;23:1-10

Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany.

We studied the effects of f.sp. (Fos), a soil-borne biocontrol agent (BCA) against , on total fungal and arbuscular mycorrhizal fungal (AMF) taxa in rhizospheres of maize in both clayey and sandy soil. Effects of Fos-BCA 'Foxy-2' were evaluated against (1) presence, and (2) organic fertilization with residues at 14, 28 and 42 d after 'Foxy-2' inoculation, via DNA-based quantitative PCR and TRFLP fingerprinting. In both soils, 'Foxy-2' occasionally promoted total fungal abundance, while the community composition was mainly altered by and . Notably, 'Foxy-2' stimulated AMF abundance, while was suppressed by . Total fungal and AMF abundance were promoted by residues. In conclusion, 'Foxy-2' resulted in no adverse effects on indigenous rhizosphere fungal communities substantiating its environmental safety as BCA against .
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http://dx.doi.org/10.1016/j.funeco.2016.05.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5045157PMC
October 2016

Soil properties, seasonality and crop growth stage exert a stronger effect on rhizosphere prokaryotes than the fungal biocontrol agent f.sp. .

Appl Soil Ecol 2016 Sep;105:126-136

Institute of Agricultural Sciences in the Tropics (Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart, Germany.

f.sp. (Fos) is an effective biocontrol agent (BCA) against the parasitic weed . It acts in the rhizosphere of several tropical cereals, where it may interfere with indigenous microbial populations. To test this impact, we assessed in a 2-season field experiment at two contrasting tropical agro-ecological sites the response of nitrifying and total indigenous prokaryotic communities in the rhizosphere of maize to the exposure of the Fos-BCA "Foxy-2". At early leaf development (EC30), flowering (EC60) and senescence (EC90) stage of maize, rhizosphere samples were obtained and subjected to community analysis of bacterial and archaeal (ammonia monooxigenase) (AOB, AOA) and 16S rRNA genes. Abundance and community composition of all studied genes were predominantly influenced by soil type, crop growth stage and seasonality. No major effect of "Foxy-2" was found. Notably, total archaeal community relative to bacteria dominated in the clayey soil which was linked to its strong soil organic carbon (SOC) background. Compared to bacterial nitrifiers, domination of nitrifying archaea increased towards senescence stage which was explained by biochemical differences in organic resource availability between the crop growth stages. During the short rain season, the higher archaeal abundance was mainly driven by increased availability of organic substrates, i.e., extractable organic carbon. Our findings suggested that archaea had greater rhizosphere competence than "Foxy-2" in soils with higher clay and SOC contents. We verified that "Foxy-2" in maize rhizospheres is compatible with nitrifying prokaryotes under the given environments, in particular in clayey soils dominated by archaea.
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http://dx.doi.org/10.1016/j.apsoil.2016.03.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6472298PMC
September 2016
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