Poster Session: Biology and Disease Management - Mycology
29-P
Interspecific competition for colonization of maize host between Fusarium proliferatum and Fusarium verticillioides.
A. REYES GAIGE (1), J. P. Stack (1)
(1) Department of Plant Pathology, Kansas State University, Manhattan, KS, U.S.A.
Fusarium proliferatum (Fp) and Fusarium verticillioides (Fv) are seed-borne pathogens of maize. They are often asymptomatic in seed eluding symptom-based detection. Although co-colonization of individual seed occurs, some seed lots are predominantly colonized by a single species. Experiments were conducted in non-sterile soil to determine if interspecific competition influenced establishment of an introduced isolate of Fp or Fv. Green fluorescent (GFP), hygromycin resistant Fp (Fp-G) and monomeric red fluorescent (mRFP) hygromycin resistant Fv (Fv-R) were developed to provide markers to track establishment in new environments. Heat-killed (75°C water bath for 20 minutes) maize seeds were colonized with Fp-G or Fv-R by immersion in a spore suspension for 16 hours. The ability of Fp-G and Fv-R to colonize viable seed already colonized by the other species was determined. Controls included competition with non-colonized cured seeds, and naturally colonized viable seeds. Plants were retrieved from soil after 14 days and observed for fluorescence. PCR amplification of partial GFP and mRFP gene sequences confirmed that Fp-G and Fv-R effectively competed against each other to colonize roots and stems of the maize plant. Fv-R colonized roots of 50% of the plants, and stems of 30% of the plants originally colonized with Fp-G; Fp-G colonized roots of 30% of the plants, and stems of 10% of the plants originally colonized with Fv-R.