University of Southern Queensland Toowoomba, Queensland, Australia
Pyrenophora teres f. teres (Ptt) causes the economically significant barley disease, net form net blotch. A bi-parental mapping population (Pop1) of 305 isolates was created by crossing two Ptt isolates: one virulent on Skiff and avirulent on Prior, and the other avirulent on Skiff and virulent on Prior. Pop1 was used to identify QTL associated with virulence on Skiff and Prior barley varieties. QTL analyses found QTL on chromosomes (Chr) 3 and 10 for Skiff virulence, and on Chr 1, 4, and 5 for Prior virulence. Major QTL on Chr 3 and 5 had LOD scores of 22 and 48, explaining 24% and 40% of phenotypic variation, respectively. A subsequent population (Pop2) was developed by crossing two Pop1 progenies: one with Chr 3 and 5 QTL, and the other avirulent with no virulence QTL. Single-QTL isolates from Pop2 were phenotyped across a Skiff/Prior recombinant inbred line (RIL) barley population to identify corresponding host genes for virulence QTL on Chr 3 and 5. Susceptibility QTL for Skiff virulence QTL on Chr 3 were located on Chr 3H and 6H, while those for Prior virulence on Chr 5 were on Chr 6H. Candidate genes for Chr 5 virulence QTL were identified through PacBio HiFi sequencing and RNA expression analyses, confirmed by qPCR. Some candidate genes are effectors, indicating both gene-for-gene and inverse gene-for-gene mechanisms in the Prior-Ptt interaction. These findings advance our understanding of the barley-P. teres interaction.
