Genetic Dissection of Resistance to the Three Fungal Plant PathogensBlumeria graminis,Zymoseptoria tritici, andPyrenophora tritici-repentisUsing a Multiparental Winter Wheat Population

Abstract

Bread wheat ( Triticum aestivum L.) is one of the world’s most important crop species. The development of new varieties resistant to multiple pathogens is an ongoing task in wheat breeding, especially in times of increasing demand for sustainable agricultural practices. Despite this, little is known about the relations between various fungal disease resistances at the genetic level, and the possible consequences for wheat breeding strategies. As a first step to fill this gap, we analyzed the genetic relations of resistance to the three fungal diseases – powdery mildew (PM), septoria tritici blotch (STB), and tan spot (TS) – using a winter wheat multiparent advanced generation intercross population. Six, seven, and nine QTL for resistance to PM, STB, and TS, respectively, were genetically mapped. Additionally, 15 QTL were identified for the three agro-morphological traits plant height, ear emergence time, and leaf angle distribution. Our results suggest that resistance to STB and TS on chromosome 2B is conferred by the same genetic region. Furthermore, we identified two genetic regions on chromosome 1AS and 7AL, which are associated with all three diseases, but not always in a synchronal manner. Based on our results, we conclude that parallel marker-assisted breeding for resistance to the fungal diseases PM, STB, and TS appears feasible. Knowledge of the genetic co-localization of alleles with contrasting effects for different diseases, such as on chromosome 7AL, allows the trade-offs of selection of these regions to be better understood, and ultimately determined at the genic level.

QTL mapping of adult plant and seedling resistance to leaf rust (Puccinia triticina Eriks.) in a multiparent advanced generation intercross (MAGIC) wheat population

“…The BMW population emerged from crosses of eight elite parental lines originating from Germany and Denmark. Nevertheless, Stadlmeier et al (2018) were able to show the potential of the BMW population to detect new QTL for resistance to powdery mildew, septoria tritici blotch, as well as tan spot, and in general the usefulness for further gene mapping studies (Stadlmeier et al 2018(Stadlmeier et al , 2019.…”

Genetic Analysis Using a Multi-Parent Wheat Population Identifies Novel Sources of Septoria Tritici Blotch Resistance

“…The QTL identified were compared with previously reported Stb genes and QTL by projecting onto the physical map in The Triticeae Toolbox (T3) database to identify the co-located genes/QTL and determine the novelty of others. For our QTL co-location study, only QTL mapping and genome-wide association scan (GWAS) studies of STB using high-throughput marker platforms were considered [60,[74][75][76][77][78][79][80][81][82][83]…”

“…Different wheat MAGIC populations have been exploited to identify QTL controlling resistance against fungal diseases such as powdery mildew (caused by Blumeria graminis), STB, tan spot (caused by Pyrenophora tritici-repentis) [59,60], and Septoria leaf and glume blotch (caused by Parastagonospora nodorum) [61]. While genetic resistance to STB has been previously identified using BMWpop [60], the phenotypic response was observed under artificial inoculation. Given that the Z. tritici pathogen population is rapidly evolving, it is important to screen the genetic resources such as MAGIC populations under natural STB infection in field conditions.…”

Genetic mapping using a wheat multi-founder population reveals a locus on chromosome 2A controlling resistance to both leaf and glume blotch caused by the necrotrophic fungal pathogen Parastagonospora nodorum

“…Multiparent advanced generation intercross (MAGIC) population designs include higher allelic diversity and higher genetic recombination rate than equivalently sized bi-parental populations and avoid the loss of power resulting from correction for subpopulation structure in AM panels (Cavanagh et al 2008;Mackay et al 2014). As a result, MAGIC populations can be used for both coarse mapping and fine mapping at relatively high resolution (Cavanagh et al 2008;Stadlmeier et al 2019). The recently developed wheat eight-founder 'NIAB Elite MAGIC' population (Mackay et al 2014) is estimated to capture around 80% of the single nucleotide polymorphism (SNP) variation in north-western European wheat germplasm (Gardner et al 2016) and includes founders of prominence within the European wheat pedigree (Fradgley et al 2019).…”