Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2002
Publication Date: October 1, 2002
Citation: Glenn, A.E., Williams, L.D., Riley, R.T. 2002. EVIDENCE FOR A FUSARIUM VERTICILLIOIDES SEEDLING PATHOGENICITY FACTOR: ALL ROADS TRAVELED LEAD TO FUMONISIN.. Aflatoxin Elimination Workshop Proceedings. October 23 - 25, 2002. San Antonio, TX. Interpretive Summary: Abstract only.
Technical Abstract: We have previously reported that Fusarium verticillioides produces an apparent seedling pathogenicity factor that results in necrotic leaf lesions and abnormal development. Genetic analysis of field isolates indicated a single locus segregated for ability to cause disease. Strains carrying the non-pathogenic allele did not cause any disease symptoms, yet still infected and endophytically colonized the corn seedlings. We have also utilized mutant strains that were greatly attenuated in their ability to infect corn seedlings yet nonetheless caused severe disease symptoms, suggesting the pathogenicity factor may be a translocated phytotoxin. Fumonisin B1 (FB1) production was assessed among the parental and progeny strains and also was found to segregate as a single locus. Linkage between pathogenicity and fumonisin production was supported since only the pathogenic strains produced FB1; non-pathogenic strains did not produce any detectable FB1. PCR targeting FUM1 and FUM9 indicated a possible deletion within the fumonisin biosynthetic gene cluster in non-producing strains, providing further support for the inability of these strains to produce FB1. Watering seedlings with solutions of FB1 showed a stimulatory effect on seedling growth at the 1 ppm concentration, yet showed small leaf lesions and obvious stunting effects on seedling development at the 10 ppm concentration. Thus far, data suggest that fumonisin is the phytotoxin causing the seedling disease symptoms, and that production of FB1 is a F. verticillioides pathogenicity factor. Further experiments will examine the dynamics of FB1 production in soils as well as the plant and fungal genes differentially expressed under the various symptomatic and asymptomatic associations between F. verticillioides and corn.