Quantitative trait loci and epistatic interactions in barley conferring resistance to net type net blotch (Pyrenophora teres f. teres) isolates

Abstract

Net type net blotch (NTNB) is an important barley disease in Australia and elsewhere, with significant yield reduction. This trait is important in selection along with other traits of quality and agronomic value. Two-hundred doubled-haploid lines were generated through anther culture from a cross between ÔPompadourÕ and ÔStirlingÕ. Quantitative trait loci (QTL) were identified against five isolates of Pyrenophora teres f. teres, which represent virulences across Australia. QTL were mapped on chromosomes 3H and 6H using simple sequence repeat (SSR) markers. The resistance locus on 6H was detected with all isolates while the 3H locus was detected with two isolates. The 6H QTL from ÔPompadourÕ contributed resistance to isolates 97NB1, 95NB100 and NB81, whereas 6H QTL from ÔStirlingÕ contributed resistance to isolates NB50 and NB52B. The 3H QTL from ÔPompa-dourÕ contributed resistance to NB50 and NB52B. Significant epistatic interactions were detected between QTL on 3H and 6H. These resistance QTL are a useful resource and identifying closely linked SSR markers with allelic combinations will facilitate in marker-assisted selection to develop NTNB resistant breeding lines.

Identifying genetic complexity of 6H locus in barley conferring resistance to Pyrenophora teres f. teres

“…Our earlier work on mapping resistance genes from ‘Pompadour’ and ‘Stirling’ (Gupta et al. 2010) detected contributions of 6H and 3H loci for NTNB resistance.…”

“…Several studies have identified NTNB resistance genes on all seven barley chromosomes using different molecular techniques (Graner et al 1996, Steffenson et al 1996, Richter et al 1998, Spaner et al 1998, Manninen et al 2000, Ma et al 2004, Friesen et al 2006, Grewal et al 2008, St Pierre et al 2010). Similarly, NTNB resistance genes on 2H, 3H, 4H and 6H were also identified in Australian cultivars at seedling and adult stages (Cakir et al 2003a, Raman et al 2003, Emebiri et al 2005, Lehmensiek et al 2007, Gupta et al 2010.…”

“…(2008) identified two resistance alleles against two isolates from California from the 6H region using EST‐based markers in a ‘Rika’ × ‘Kombar’ population. Gupta et al. (2010) identified this region in ‘Pompadour’ and ‘Stirling’ using SSR markers.…”

Necrotrophic effector‐triggered susceptibility (NETS) underlies the barley–Pyrenophora teres f. teres interaction specific to chromosome 6H

“…The 6H QTL region has been reported in several previous studies using a variety of host populations and pathogen isolates (see review by Liu et al ., ). It is likely that multiple resistance/susceptibility genes are present at the 6H locus, not only because of the number of reports of the 6H region, but also because of the report of this region harbouring both dominant and recessive forms of resistance (Abu Qamar et al ., ; Friesen et al ., ; Gupta et al ., ; St. Pierre et al ., ). In the current study, we found that the 6H association with susceptibility was identified for six of the 10 isolates tested, with these six being geographically diverse.…”

“…Several studies using various RIL and doubled haploid (DH) mapping populations have identified a region on chromosome 3H which, on the basis of common markers, appears to be in the same region as the major 3H QTLs reported here (Graner et al ., ; Gupta et al ., , ; Raman et al ., ; Yun et al ., ). At least three of these studies also used the Australian isolate NB50 (Gupta et al ., , ; Raman et al ., ). Using this same NB50 isolate on the HN population, we also detected a major QTL on 3H ( R 2 = 0.66) in addition to two minor effect QTLs on 3HL and 5HS.…”