DNA HOMOLOGY BETWEEN PYRENOPHORA-JAPONICA AND P-TERES

Pyrenophora isolates associated with net- and spot type net blotch of barley were compared with verified isolates of P. teres f. teres, P. t eres f. maculata and P. japonica using total DNA banding patterns, mor phology, symptomatology and mating studies. DNA of South African and o verseas spot- and net-type isolates digested with Hae III and Msp I sh owed 74-100% similarity. Furthermore, spot- and net-type isolates coul d be mated to produce viable progeny, indicating P. teres to have two- allele heterothallism. Single-ascospores inoculated on differential ba rley cultivars produced spot net or mixed symptoms, suggesting that re combination has occurred. Based on the high degree of homology in DNA banding patterns between P. japonica and P. teres f. maculata, as well as similarities in symptom expression on differential cultivars and g eneral morphology, P. japonica is proposed as synonym of P. teres.