TY - JOUR
T1 - Microbiological factors affecting the colonisation of soil aggregates by Fusarium oxysporum f. sp. raphani
AU - Toyota, Koki
AU - Ritz, Karl
AU - Young, Iain M.
N1 - Generated from Scopus record by KAUST IRTS on 2023-02-15
PY - 1996/1/1
Y1 - 1996/1/1
N2 - To elucidate factors that affect the colonization of soil aggregates by Fusarium oxysporum f. sp. raphani PEG-4 (hereafter PEG-4), microcosms were designed which comprised a row of three soil aggregates 4 6 mm dia. placed 2 mm apart on silicone rubber podia. The central aggregate was sterile and inoculated with PEG-4. The lateral aggregates were non-sterile or treated in various ways to affect their microbiological status. Following incubation, propagule populations of PEG-4 in the lateral aggregates were enumerated. The degree to which PEG4 colonized non-sterile aggregates was less than 1% of the control (sterile aggregates). When non-sterile aggregates were dried to 200 kPa or antibiotics were added to them to inhibit bacteria, colonization by PEG-4 did not differ greatly from the control, suggesting that the suppressing factors might be of fungal origin. That PEG-4 colonized chloroform-fumigated aggregates, where there was a relative abundance of bacteria supported this hypothesis. In addition sterile aggregates which had been colonized by a range of soil fungi generally inhibited PEG-4 to a greater extent than aggregates which had been colonized by single strains of bacteria. The fungal strains that showed the greatest resistance to the establishment of PEG-4 were closely related to it (F. oxysporum f. sp. raphani, F. nivale, F. oxysporum f. sp. cucumerinum). An antibiotic-producing bacteria, Burkholdier cepacia MRT 11, was also effective at inhibiting PEG-4. Outcomes of interactions between PEG-4 and the other microbes on agar plates were poorly correlated with the outcomes in the aggregate system. We suggest that such aggregate-based systems may be useful in screening putative biocontrol agents since they are soil-based and effects can be readily assessed.
AB - To elucidate factors that affect the colonization of soil aggregates by Fusarium oxysporum f. sp. raphani PEG-4 (hereafter PEG-4), microcosms were designed which comprised a row of three soil aggregates 4 6 mm dia. placed 2 mm apart on silicone rubber podia. The central aggregate was sterile and inoculated with PEG-4. The lateral aggregates were non-sterile or treated in various ways to affect their microbiological status. Following incubation, propagule populations of PEG-4 in the lateral aggregates were enumerated. The degree to which PEG4 colonized non-sterile aggregates was less than 1% of the control (sterile aggregates). When non-sterile aggregates were dried to 200 kPa or antibiotics were added to them to inhibit bacteria, colonization by PEG-4 did not differ greatly from the control, suggesting that the suppressing factors might be of fungal origin. That PEG-4 colonized chloroform-fumigated aggregates, where there was a relative abundance of bacteria supported this hypothesis. In addition sterile aggregates which had been colonized by a range of soil fungi generally inhibited PEG-4 to a greater extent than aggregates which had been colonized by single strains of bacteria. The fungal strains that showed the greatest resistance to the establishment of PEG-4 were closely related to it (F. oxysporum f. sp. raphani, F. nivale, F. oxysporum f. sp. cucumerinum). An antibiotic-producing bacteria, Burkholdier cepacia MRT 11, was also effective at inhibiting PEG-4. Outcomes of interactions between PEG-4 and the other microbes on agar plates were poorly correlated with the outcomes in the aggregate system. We suggest that such aggregate-based systems may be useful in screening putative biocontrol agents since they are soil-based and effects can be readily assessed.
UR - https://linkinghub.elsevier.com/retrieve/pii/S0038071796001654
UR - http://www.scopus.com/inward/record.url?scp=0030251142&partnerID=8YFLogxK
U2 - 10.1016/S0038-0717(96)00165-4
DO - 10.1016/S0038-0717(96)00165-4
M3 - Article
SN - 0038-0717
VL - 28
SP - 1513
EP - 1521
JO - Soil Biology and Biochemistry
JF - Soil Biology and Biochemistry
IS - 10-11
ER -