Biological Species and Effective Population Number in Gibberella fujikuroi Species Complex Recovered from Sorghum in Egypt

Sorghum growing fields surveyed for the infection by Fusarium stalk and head rots throughout five locations in Egypt were screened depending on section Liseola characteristics. A number of 137 isolates from total recovered in average 87.8% isolates belonged to this section. These isolates selected from the whole number recovered from this group of fungi were subjected to the identified biologically and screened for fumonisin FB1 production. A number of 111 isolates produced fumonisin FB1 in average 81% from total isolates belonged to section Liseola. Four mating populations were identified, a number of 70 isolates mating population (MATP-A) F. verticillioides, 29 (MATP-D) F. proliferatum, 21 (MATP-F) F. thapsinum and 17 (MATP-G) F. nygamai. Mating population, A F. verticillioides consisted of 46 mating type 1 (MAT-1) and 24 mating type 2 (MAT-2), (MATP-D) F. proliferatum consisted of only 18 strains of (MAT-1) and 11 of (MAT-2). Whereas (MATP-F) F. thapsinum consisted of 14 strains of (MAT-1) and 7 of (MAT-2) and (MATP-G) F. nygamai consisted of only 12 strains of (MAT-1) and 5 of (MAT-2). Isolates belong to MATP-A produced considerable amounts of fumonisin compared to those belong to MATP-D,F and G. Female fertile strains could produce higher amounts of the toxin than female sterile. Measuring the parameters of the effective population number in four biological species recovered from sorghum, it was found that the female sterility was lesser than 50% in mating population A (21.4%) and were high in MATP- D, F and G (58.6%, 61.9% and 64.7%, respectively). This caused decrease in effective population number based on female fertility (Ne_f) overall locations in MATP- D, F and G, but it was high in MATP-A. Ration between Mating types (Mat-1, Mat-2) were differed from location to other also differed in population, it was high in all Mating populations than (Ne_f). These results in MATP-A led to an advantage during sexual reproduction occurs. Whereas MAT-D, F and G population vegetative propagation were significant component of the fungus especially in Assiut MATP-D, based on (Ne_mt) and population of Minia MATP-G, Sohag MATP-F based on (Ne_f).