Strains of Trichoderma harzianum possess biocontrol capabilities.
As background for identification of strain-specific markers for
monitoring strains of interest, the relationship of strains designated
as T. harzianum, including representatives of three biological
forms Th1, Th2 and Th3, were analysed by Universally Primed PCR, UP-PCR,
using UP and random primers. Cross dot blot
hybridization of UP-PCR products generated with either of two different
UP primers or a random primer showed unequivocal
differences among strains. Using this approach, T. harzianum strains
were distributed into two different genotypic groups. One of the
T. harzianum groups included forms Th1 and Th2 while the other
group accounted for the Th3 form. The relatedness of strains of
each group was estimated by UPGMA analysis based on markers revealed with
three primers. It was found that both genotypic
groups are heterogeneous, and Th2 form strains definitely cluster together
with those of Th1. Division of the three biological forms
of T. harzianum into two groups was also supported by rDNA-ITS1
analysis, where Sau3A digestion of the amplified ITS1 region
gave a restriction fragment profile specific for each genotypic group.
Two strains with known biocontrol capabilities were found to
relate to the genotypic group containing Th1 and Th2 forms and, based on
variation within this group, to belong to a
homogeneous group of form Th1 strains. The robustness and reliability of
UP-PCR fingerprinting were demonstrated by obtaining
identical banding profiles using different conditions for PCR in different
laboratories.