Submitted to: Canadian Journal of Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/2/2003
Publication Date: 12/20/2003
Citation: FRIESEN, T.L., ALI, S., STACK, R.W., FRANCL, L.J., RASMUSSEN, J.B. RAPID AND EFFICIENT PRODUCTION OF THE PYRENOPHORA TRITICI-REPENTIS TELEOMORPH.. CANADIAN JOURNAL OF BOTANY. 2003. VOL. 81:890-895. Interpretive Summary: Pyrenophora tritici-repentis is the fungus that causes tan spot of wheat. Tan spot is an economically important foliar disease that causes yield loss to wheat crops throughout the world. In order to better study the genetics of disease caused by the fungus we have identified parameters required for fast, efficient production of the sexual stage of this fungus in culture. Parameters tested include light cycle, temperature and growth medium. Optimum parameters include incubating the fungus on maize leaves placed on water agar in continuous darkness for 12 days followed by a 12 h photoperiod all at 100% relative humidity. This resulted in sexual stage maturity (ascospore discharge) in 29 days. This technique will be helpful to researchers studying the biology of sexual stage development, disease epidemiology and genetics of this fungus.
Technical Abstract: Laboratory conditions were identified for efficient production of the teleomorph of Pyrenophora tritici-repentis, causal agent of tan spot of wheat. Ascocarp density (pseudothecia per 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 degrees Centigrade. 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.