Biocontrol Efficacy Among Strains of Pochonia chlamydosporia Obtained from a Root-Knot Nematode Suppressive Soil

Three Pochonia chlamydosporia var. chlamydosporia strains were isolated from a Meloidogyne incognita-suppressive soil, and then genetically characterized with multiple Pochonia-selective typing methods based on analysis of beta-tubulin, rRNA internal transcribed spacer (ITS), rRNA small subunit (SSU), and enterobacterial repetitive intergenic consensus (ERIC) PCR. All strains exhibited different patterns with the ERIC analysis. Strains 1 and 4 were similar with PCR analysis of beta-tubulin and ITS. The strains' potential as biological control agents against root-knot nematodes were examined in greenhouse trials. All three P. chlamydosporia strains significantly reduced the numbers of nematode egg masses. When chlamydospores were used as inoculum, strain 4 reduced egg numbers on tomato roots by almost 50%, and showed effects on the numbers of J2 and on nematode-caused root-galling. A newly developed SSU-based PCR analysis differentiated strain 4 from the others, and could therefore potentially be used as a screening tool for identifying other effective biocontrol strains of P. chlamydosporia var. chlamydosporia.