An explicit AFLP-based marker for monitoring Fusarium oxysporum f.sp strigae in tropical soils

作者：Zimmermann Judith; de Klerk Madelein; Musyoki Mary K; Viljoen Altus; Watson Alan K; Beed Fen; Gorfer Markus; Cadisch Georg; Rasche Frank^*

来源：Biological Control, 2015, 89: 42-52.

DOI：10.1016/j.biocontrol.2015.02.008

• Fusarium oxysporum f.sp strigae
• Striga hermonthica
• Biological control agent
• AFLP
• Molecular marker
• Quantitative PCR
• Monitoring

Our objective was to develop an explicit AFLP-marker to quantify the abundance of Fusarium oxysporum f.sp. strigae (Fos), an effective soil-borne biocontrol agent (BCA) against the parasitic weed Striga hermonthica, in tropical soils. The specificity of the AFLP-marker to Fos was confirmed on basis of comparison of Fusarium isolates of differing relatedness to Fos. These consisted of 40 Fos, 17 Fusarium spp. and 68 F. oxysporum isolates retrieved from tropical and temperate ecosystems. The robustness of the AFLP-marker for monitoring Fos was validated in a controlled incubation experiment. In this experiment, we inoculated the known Fos-BCA "Foxy-2'' as model organism via seed coating (1.15 * 105 colony forming units per seed) of a tropical maize (Zea mays L.) variety to a tropical clayey (Humic Nitisol) and a sandy (Ferric Alisol) soil, both with no indigenous Fos infestation. The proliferation of "Foxy-2'' was followed at 14, 28 and 42 days after start of experiment by Fos-specific quantitative PCR using the AFLP-marker. Moreover, the experimental set-up considered two additional factors: (1) presence of S. hermonthica, and (2) application of Tithonia diversifolia residues as nitrogen-rich resource for supporting "Foxy-2'' proliferation. The explicit AFLP-marker was appropriate to reveal that soil type and organic resource availability exhibited distinct effects on abundance of inoculated "Foxy-2''. Negative PCR signals, which confirmed the Fos-specificity of the developed AFLP-marker, were retrieved from control soils not inoculated with "Foxy-2''. Hence, we verified the applicability of the explicit AFLP-marker for Fos in two soils, but recommend additional broad scale field studies to approve its suitability as Fos monitoring tool for differently managed soils in contrasting tropical agro-ecological zones.

• 出版日期2015-10
• 单位McGill