Genetic diversity of fusarium isolates from corn: differentiation by vegetative compatibility and aggressiveness
2007
Cumagun, C.J.R., Philippine Univ. Los Baños, College, Laguna (Philippines). Crop Protection Cluster
Fussarium verticilliodes is a common mycotoxigenic pathogen of corn. Eighty isolates were collected from healthy and infected corn cobs from Laguna [Philippines]. Fifty isolates cross with one mating type A testers. The ratio of MATA1:MATA2 27:23 which followed a mendelian ratio of 1:1. The effective population number Ne sub (mt) of these population was determined by mating type and male/hermaphrodite polymorphisms. The effective population number for mating type, Ne sub (mt) is 81% of the count (total population). Sexual reproduction in Philippine isolates of F. verticilliodes does not occur frequently compared to F. verticillioides in other regions of the world. Twenty isolates of G. fujikuroi each from Laguna and Isabela [Philippines] were characterized at the molecular level by mating population (MP) and Mating Type (MAT) and vegetative compatibility group (VCG)(only for Laguna isolates) in the laboratory and tested for their stalk rot aggressiveness under field conditions across two environments using the toothpick inoculation method. In two greenhouse trials, inhibition of seedling emergence, seedling height, fresh and dry weight was also determined. Fumonism production was analyzed by High Performance Liquid Chromatography (HPLC). Significant (P=0.05) differences in aggressiveness toward super sweet corn variety of some isolates were observed for both experimental locations while VCG by pairing nit mutants identified 19 VCGs for the Laguna population with a genotype diversity of 0.95. All isolates were pathogenic to corn seedlings and mature plants compared to non-inoculated control. There was a low correlation between the aggressiveness of Laguna and Isabela isolates and their fumonism production (r=0.32-0.38).
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