High-resolution mapping of genes involved in plant stage-specific partial resistance of barley to leaf rust

Abstract

Partial resistance quantitative trait loci (QTLs) Rphq11 and rphq16 against Puccinia hordei isolate 1.2.1 were previously mapped in seedlings of the mapping populations Steptoe/Morex and Oregon Wolfe Barleys, respectively. In this study, QTL mapping was performed at adult plant stage for the two mapping populations challenged with the same rust isolate. The results suggest that Rphq11 and rphq16 are effective only at seedling stage, and not at adult plant stage. The cloning of several genes responsible for partial resistance of barley to P. hordei will allow elucidation of the molecular basis of this type of plant defence. A map-based cloning approach requires to fine-map the QTL in a narrow genetic window. In this study, Rphq11 and rphq16 were fine-mapped using an approach aiming at speeding up the development of plant material and simplifying its evaluation. The plant materials for fine-mapping were identified from early plant materials developed to produce QTL-NILs. The material was first selected to carry the targeted QTL in heterozygous condition and susceptibility alleles at other resistance QTLs in homozygous condition. This strategy took four to five generations to obtain fixed QTL recombinants (i.e., homozygous resistant at the Rphq11 or rphq16 QTL alleles, homozygous susceptible at the non-targeted QTL alleles). In less than 2 years, Rphq11 was fine-mapped into a 0.2-cM genetic interval and a 1.4-cM genetic interval for rphq16. The strongest candidate gene for Rphq11 is a phospholipid hydroperoxide glutathione peroxidase. Thus far, no candidate gene was identified for rphq16.Electronic supplementary materialThe online version of this article (doi:10.1007/s11032-017-0624-x) contains supplementary material, which is available to authorized users.

A Cluster of MYB Transcription Factors Regulates Anthocyanin Biosynthesis in Carrot (Daucus carota L.) Root and Petiole

“…In addition, fine mapping of QTL in population 70349 confirmed previous results of Cavagnaro et al (2014) reporting co-localization of RTPE-Q1 and four major QTL for individual anthocyanin pigments, and further narrowed this map region from 12 to 6.3 cM, with four of the QTL (including RTPE-Q1 ) being within a 3 cM region. This increase in map resolution in the RTPE-Q1 region, as consequence of using a larger population size and more markers, has also proven successful for other QTL and species (Chen et al, 2016; Yeo et al, 2017), and facilitated the search of candidate genes for anthocyanin pigmentation to a more-confined genomic region.…”

Expression polymorphism at the ARPC4 locus links the actin cytoskeleton with quantitative disease resistance to Sclerotinia sclerotiorum in Arabidopsis thaliana

“…In nonlimiting conditions, plant morphology and development also may contribute to pathogen resistance (Kliebenstein, ). Mapping of QDR genes points towards specific resistance genes associated with plant developmental stages in plant–fungus interactions (Wang et al ., ; Yeo et al ., ). Genes involved in plant development may be directly associated with disease resistance, such as a maize caffeoyl‐CoA O ‐methyltransferase playing important structural role in plant cell walls through lignin synthesis, and conferring broad spectrum resistance to fungal pathogens (Yang et al ., ).…”

Inheritance of nonhost resistance of barley to the powdery mildew fungi of cereals and grasses

“…In chapter 3 we report on the fine-mapping and important steps towards the map-based cloning of Rbgnq1. A commonly used approach for fine-mapping requires the introgression of the QTL into near-isogenic lines (NILs), which is a very effective strategy because no additional QTL will be segregating in the background and thus influence the phenotype of the trait of interest (Yeo et al 2017). The development of NILs is, however, very time-consuming.…”