Effectiveness of Myrothecium roridum for controlling water hyacinth and species identification based on molecular data

Myrothecium roridum isolates were evaluated for their effectiveness in controlling the aggressive water hyacinth and molecular identification was conducted using internal transcribed spacer (ITS) rDNA region and amplified fragment length polymorphism (AFLP) markers. M. roridum isolates were collected from nine provinces of Thailand. Seventy isolates were included in the primary screening, using colonial growth rate and spore number measurement. The results indicate that five isolates were the most aggressive and so were selected to evaluate their effectiveness in controlling the water hyacinth. The result showed that M. roridum isolate KKFC 408 had significantly highest disease severity (P<0.05) and the highest reduction for the fresh weight of water hyacinth. These five isolates DNA were amplified and sequenced using ITS1 and ITS4 universal primer for species identification. The data analyzed showed that five sequences of M. roridum were in the same group agreeing with other sequences of M. roridum recorded in the GenBank database, which correlated to morphological observation results. The AFLP result indicated that fifteen isolates of M. roridum were divided into four subgroups which were not correlated to the geographical area.   Key words: Amplified fragment length polymorphism (AFLP), internal transcribed spacer (ITS) of rDNA region, mycoherbicide.