Wd. Chen et al., Specific detection of Phialophora gregata and Plectosporium tabacinum in infected soybean plants using polymerase chain reaction, MOL ECOL, 8(5), 1999, pp. 871-877
The fungal deuteromycetes Phialophora gregata and Plectosporium tabacinum a
re associated with soybean plants. I? gregata causes brown stem rot (BSR) o
f soybean, whereas P. tabacinum is a frequent cohabitant of soybean stems.
The role of P. tabacinum in soybean growth and in the development of BSR is
not known. Traditional methods of isolating and differentiating these two
fungi require up to 3 weeks to complete. In order to effectively study the
interactions among P. gregata, P. tabacinum, and the soybean plant, we deve
loped specific primers for P. tabacinum based on its rDNA internal transcri
bed spacer sequences. In combination with specific primers developed previo
usly for P. gregata, the specific primer pairs were used successfully in po
lymerase chain reactions to detect the targeted fungi in both artificially
inoculated and naturally infected soybean plants. Using this technique, we
examined 130 soybean plants collected from natural field environments for t
he presence or absence of P. gregata and P. tabacinum. Statistical analyses
of the results showed that the frequency of co-occurrence of P. gregata an
d P. tabacinum in soybean plants was significantly less than expected if th
e two fungi would occur independently, suggesting that one of the fungi may
be inhibitory to the other fungus.