Mj. Huss et al., ISOZYME VARIATION AMONG BIOLOGICAL SPECIES IN THE GIBBERELLA-FUJIKUROI SPECIES COMPLEX (FUSARIUM SECTION LISEOLA), Applied and environmental microbiology, 62(10), 1996, pp. 3750-3756
lsozyme phenotypes were determined for 101 strains of Gibberella fujik
uroi and 2 strains of Gibberella nygnmai that represent seven biologic
al species (mating populations) isolated from a variety of plant hosts
in dispersed geographic locations, Fourteen enzymes were resolved in
one ol more of three buffer systems, Two of the enzymes, arylesterase
and acid phosphatase, were polymorphic within two or more biological s
pecies and are suitable for intraspecific studies of population variat
ion, Six enzymes, alcohol dehydrogenase, aspartate aminotransferase, g
lucose-6-phosphate dehydrogenase, mannitol dehydrogenase, phosphogluco
mutase, and phosphogluconate dehydrogenase, were monomorphic in all of
the isolates examined, The remaining six enzymes, fumarase, glucose p
hosphate isomerase, glutamate dehydrogenase (NADP), isocitrate dehydro
genase (NADP), malate dehydrogenase, and triose-phosphate isomerase, c
ould potentially be used to distinguish the different biological speci
es, Mating populations C and D are the most similar, since the mating
population C isolates examined had the same isozyme phenotype as did a
subset of the isolates in mating population D, Mating population E is
the least similar to the other taxa examined, Unique isozyme phenotyp
es are present but are composed of banding patterns shared among the b
iological species, This finding supports the hypothesis that these bio
logical species, with the possible exception of mating populations C a
nd D, are reproductively isolated from one another and that no signifi
cant gene how is occurring between them, Isozyme analysis is a useful
method to distinguish these closely related biological species, Examin
ation of isozyme phenotypes is more rapid than the present technique,
which is based on sexual crosses; can be applied to strains that are n
ot sexually fertile; and is more sensitive than traditional morphologi
cal characters, which cannot distinguish more than three or four morph
ological groups among the seven biological species, While emphasizing
the discreteness of the mating populations as biological entities, our
isozyme data also reaffirm the close genetic relationship among these
groups.