Bd. Mccallum et al., GENERATION AND UTILIZATION OF CHEMICAL-RESISTANT MUTANTS IN PYRENOPHORA-TRITICI-REPENTIS, THE CAUSAL AGENT OF TAN SPOT OF WHEAT, Canadian journal of botany, 72(1), 1994, pp. 100-105
Tan spot, caused by the fungal pathogen Pyrenophora tritici-repentis,
is a major leaf spot disease of wheat worldwide. To facilitate genetic
analysis of this homothallic fungus, mutants resistant to the fungici
de iprodione or hygromycin B were created through ultraviolet light mu
tagenesis and used in sexual crosses. Conidia from two isolates of P.
tritici-repentis, sensitive to both chemicals (iprodione-S hygromycin-
S), were exposed to ultraviolet light to obtain four mutants resistant
to iprodione but sensitive to hygromycin B (iprodione-R hygromycin-S)
and three mutants resistant to hygromycin B but sensitive to iprodion
e (iprodione-S hygromycin-R). The mutants were paired in all combinati
ons, and the markers allowed crossed progeny to be distinguished from
selfed progeny. Crossed ascospore progeny from pairings between iprodi
one-R hygromycin-S isolates and iprodione-S hygromycin-R isolates and
between iprodione-R hygromycin-a isolates and iprodione-S hygromycin-S
segregated 1:1 for resistance-sensitivity to both iprodione and hygro
mycin B. These results indicate that one locus controls iprodione resi
stance and a second independent locus controls hygromycin B resistance
. This study should facilitate further genetic research on the tan spo
t fungus by providing a simple marker system.