Rapid and efficient production of the Pyrenophora tritici-repentis teleomorph

Abstract

Laboratory conditions were identified for efficient production of the teleomorph of Pyrenophora tritici-repentis, causal agent of tan spot of wheat. Ascopcarp density (pseudothecia/cm2) and timing of ascospore maturity and discharge were determined for the fungus incubated on green or senescent maize leaves under various light regimes at 15 °C. The most rapid ascospore maturity (20 days) and discharge (26 days) occurred in a 12-h photoperiod on green leaves. However, incubation in continuous darkness increased ascocarp density. Rapid and efficient ascospore production was obtained by incubating the fungus on senescent leaves in continuous darkness for 12 days followed by a 12-h photoperiod. This resulted in ascospore discharge in 29 days from a high density of pseudothecia. Further, 95% of pseudothecia sampled contained mature ascospores at the time of first discharge. The maximum ascospore discharge height observed was 8.8 cm. Pseudothecial neck development was positively phototropic.Key words: Drechslera, ascomycete, loculascomycete, tan spot, ascospore, pseudothecium