Characterization of Spot Form Net Blotch Susceptibility/Resistance in Barley

The disease spot form net blotch (SFNB) caused by the necrotrophic fungal pathogen Pyrenophora teres f. maculata (Ptm), is a major threat to barley (Hordeum vulgare L.) production worldwide. Four Ptm isolates from different regions of the world (USA, Australia, New Zealand, and Denmark) were utilized to screen 1,947 lines from the National Small Grains World Barley Collection. Fifteen lines with high levels of resistance to all isolates tested were identified with the accession (PI67381) from Turkistan exhibiting the highest levels of resistance. A cross was made between PI67381 and the popular Upper Midwest 6-rowed malting variety ‘Tradition’ and F₁ seed was sent to Oregon State University for the development of a doubled haploid population. Utilizing the 9K SNP genotype data mined from the Triticeae Coordinated Agriculture Project (T-CAP) T3 database a 384 SNP marker platform was designed that is specific to the PI67381 × Tradition population. The polymorphic SNP markers were selected to be evenly distributed, at ~5 cM intervals, across all seven barley chromosomes. We are utilizing a PCR based genotype-by-sequencing method optimized for Ion Torrent next generation sequencing to genotype the DH population. The development of robust genetic maps will allow for the genetic characterization of SFNB resistance and/or susceptibility utilizing phenotypic data generated with virulent Pyrenophora teres f. maculata isolates collected from North Dakota and Montana. The individual DH lines containing all resistance and/or lack of susceptibility QTL from PI67381 will then be utilized in backcrossing strategies to develop elite pre-breeding lines with broad SFNB resistance.