Dissection of quantitative and durable leaf rust resistance in Swiss winter wheat reveals a major resistance QTL in the Lr34 chromosomal region

Abstract

The Swiss winter bread wheat cv. 'Forno' has a highly effective, durable and quantitative leaf rust ( Puccinia triticina Eriks.) resistance which is associated with leaf tip necrosis (LTN). We studied 240 single seed descent lines of an 'ArinaxForno' F(5:7 )population to identify and map quantitative trait loci (QTLs) for leaf rust resistance and LTN. Percentage of infected leaf area (%) and the response to infection (RI) were evaluated in seven field trials and were transformed to the area under the disease progress curves (AUDPC). Using composite interval mapping and LOD >4.4, we identified eight chromosomal regions specifically associated with resistance. The largest and most consistent leaf rust resistance locus was identified on the short arm of chromosome 7D (32.6% of variance explained for AUDPC_% and 42.6% for AUDPC_RI) together with the major QTL for LTN ( R(2)=55.6%) in the same chromosomal region as Lr34 ( Xgwm295). A second major leaf rust resistance QTL ( R(2)=28% and 31.5%, respectively) was located on chromosome arm 1BS close to Xgwm604 and was not associated with LTN. Additional minor QTLs for LTN (2DL, 3DL, 4BS and 5AL) and leaf rust resistance were identified. These latter QTLs might correspond to the leaf rust resistance genes Lr2 or Lr22 (2DS) and Lr14a (7BL).

Analysis of leaf and stripe rust severities reveals pathotype changes and multiple minor QTLs associated with resistance in an Avocet × Pastor wheat population

“…The first QTL gave a LOD of 4.4 against leaf rust severity, and the second was for stripe rust severity and gave a LOD of 6.6. These loci correspond to a region that had previously been identified as containing a QTL for leaf rust severity in the winter wheat ''Forno'' Schnurbusch et al 2004). Lin and Chen (2009) also identified a 1B QTL that contributed a small degree of resistance to stripe rust but they could not conclude whether this locus was Lr46/Yr29.…”

“…To further clarify the relative locations of all published 1B QTLs Lillemo et al 2008;Schnurbusch et al 2004;Messmer et al 2000;Melichar et al 2008;Lin and Chen 2009;Rosewarne et al 2006;William et al 2006; and this study), map positions of QTL-flanking markers were investigated on consensus maps (Fig. 1) sourced from the CMAP website (http://ccg.murdoch.edu.…”

“…The 2A and 2D QTLs had LOD scores of 3.8 and 4.8, respectively. Leaf rust resistance QTLs on 2AL have previously been identified by Schnurbusch et al (2004) and on 2D by Xu et al (2005). It is currently unknown if these are in the same region as the Pastor QTL.…”

“…Slow-rusting QTLs have previously been identified on 7BL for stripe rust severity Lin and Chen 2007), leaf rust severity (Xu et al 2005;Schnurbusch et al 2004;Nelson et al 1997) and both diseases (Rosewarne et al 2008). The map positions of flanking markers in these studies are summarised in Fig.…”

Phenotypic and Molecular Characterization of Wheat Leaf Rust Resistance Gene <i>Lr34</i> in Iranian Wheat Cultivars and Advanced Lines

“…Application of previously developed markers, such as gwm295 and gwm1220 [19,20], has shown their limited use in breeding application due to their low diagnostic capability in precise detection of Lr 34 in different genetic backgrounds. During the last few years significant progress has been made in the development of more closely linked markers for Lr 34 /Yr 18 complex trait such as SWM10 and csLV34 [21].…”