Adult-plant resistance to Septoria tritici blotch in hexaploid spring wheat

Abstract

New QTL for Septoria tritici blotch detected in hexapoid spring wheat under field conditions across diverse environments. Septoria tritici blotch caused by the ascomycete fungus Zymoseptoria tritici presents a serious and consistent challenge to global wheat production. In particular the augmented use of soil management practices that leave large amounts of wheat stubble on the soil surface and global warming increases the chance of Septoria tritici blotch epidemics to emerge more frequently including in developing countries. Two recombinant inbred line populations developed from a cross between the susceptible Moroccan spring bread wheat variety 'NASMA' and the CIMMYT resistant lines, 'IAS20*5/H567.71' and 'RPB709.71/COC' were used to study the genetics and map adult-plant resistance to Septoria tritici blotch under field conditions in different environments. Resistance to Septoria tritici blotch in both populations was quantitative and overall, five across environment consistent resistance loci on chromosomes 1BS, 3AL, 5AL and 7AS were detected in the two populations. The QTL on chromosome 1BS and 7AS are likely to be allelic with the known Septoria tritici blotch genes Stb3 and Stb11. All identified QTL were additive and explained between 4 and 27 % of the phenotypic variation. Epistatic interaction was not observed. Low cost KASP assays were developed as flanking markers for all five QTL that will facilitate molecular breeding. Our study represents the first mapping effort under field conditions utilizing two spring bread wheat resistant sources evaluated over multiple environments.

Genomewide association study reveals novel quantitative trait loci associated with resistance towards Septoria tritici blotch in North European winter wheat

“…Generally, qualitative resistance genes explain a large part of the variance, and this will also be reflected as high LOD scores (Raman & Singh, 2015). This also suggests that the chromosomal regions found in this study are quantitative resistance genes.…”

“…As the GWAS resulted in relatively low LOD scores and R 2 values, the four QTL are most likely to be quantitative resistance genes. Additionally, earlier studies have identified STB resistance as a quantitative trait, rather than a qualitative (Dreisigacker, Wang, Cisneros, Jing, & Singh, ). This also suggests that the chromosomal regions found in this study are quantitative resistance genes.…”

Anther Extrusion and Its Association with Fusarium Head Blight in CIMMYT Wheat Germplasm

“…Additionally, alleles for the plant height and vernalization genes Rht-B1, Rht-D1, and Vrn-A1 were also determined, using Kompetitive allele specific PCR (KASP) assays (LGC Genomics applications note, http://www.kbioscience.co.uk/reagents/KASP_Taqmancomparison.pdf) described in Dreisigacker et al [25]. Additionally, some simple sequence repeat (SSR) markers were previously mapped in these two populations for studying Septoria tritici blotch resistance [26]. Markers with missing data points greater than 20% and segregation ratio beyond the range 0.5-2.0 were discarded from further analysis.…”

Sources of resistance and susceptibility to Septoria tritici blotch of wheat

“…More significant in wheat breeding is partial or quantitative resistance (QR), which is incomplete but generally effective against all genotypes of a pathogen, and is usually durable (Brown, ; Niks et al ., ). Numerous quantitative trait loci (QTLs) for QR to Septoria have been reported (reviewed by Brown et al ., ; see also Adhikari et al ., ; Dreisigacker et al ., ).…”