ASSIGNMENT OF A PCR-AMPLIFIED CHITINASE SEQUENCE CLONED FROM TRICHODERMA-HAMATUM TO RESOLVED CHROMOSOMES OF POTENTIAL BIOCONTROL SPECIES OFTRICHODERMA

A 1424 bp DNA sequence containing the genetic determinants of the chit inase enzyme was identified in Trichoderma hamatum by PCR amplificatio n. High levels of similarity were observed between this sequence, name d Th-ch (T. hamatum chitinase), and the 42 kDa chitinase genes known f rom T. harzianum. Chromosome-sized DNAs of five potential biocontrol s pecies of Trichoderma were separated by pulsed-field gel electrophores is. The total number of chromosomes was six in all the species, with s izes ranging from 3.7 to 7.7 Mb; estimated genome sizes were between 3 0.5 and 35.8 Mb. When fractionated chromosomes of the five species wer e probed with radiolabelled Th-ch, strong hybridization signals develo ped in all cases, but the physical position of these signals varied am ong species indicating a polymorphic chromosomal location of the highl y conserved 42 kDa chitinase gene within the genus Trichoderma.