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Candidate effector gene of spot form net blotch identification using genetic mapping and whole genome sequencing

Shaun Clare: North Dokata State University

<div>Net blotch is a destructive necrotrophic foliar pathogen of barley and occurs as net and spot forms caused by <em>Pyrenophora teres </em>f. <em>teres</em> and <em>P. teres </em>f. <em>maculata </em>(<em>Ptm</em>), respectively<em>. </em>Recently, <em>Ptm </em>has become prevalent in the Northern Great Plains, USA. A 118-progeny bi-parental mapping population was developed from the virulent Montana isolate ‘PA14’ and the avirulent California isolate ‘CAWB’ (collected from wild barley) to investigate the <em>Ptm­-</em>barley interaction. Progeny isolates were phenotyped on a differential set of barley lines and genotyped using RAD-GBS. Genetic maps were developed for QTL analysis identifying a total of four QTL across three of the 12 linkage groups. One locus mapped to an 11.9cM genetic interval and accounted for 21-39% (LOD 7.0-18.9) of the phenotypic variation. A reference quality sequence was assembled for North Dakota isolate ‘FGO’ using PacBio sequencing. Analysis of the 11.9cM interval in the reference isolate revealed a 113.5 kb region containing 34 genes. Five of the 34 genes were predicted to contain a secretion signal, of which only two were under 250 amino acids. Only one of the genes was expressed and is therefore the top candidate effector gene. This locus has been identified in two additional mapping populations, with parents contributing virulence all harboring an identical candidate gene sequence to ‘PA14’. Validation of this gene utilizing gain- and loss-of-function gene transformation is in progress.</div>