1RS arm of Secale cereanum 'Kriszta' confers resistance to stripe rust, improved yield components and high arabinoxylan content in wheat

Abstract

Wheat-rye T1BL.1RS translocation is widespread worldwide as the genes on 1RS arm have positive effect on stress resistance, grain yield and adaptation ability of wheat. Nowadays, the T1BL.1RS wheat cultivars have become susceptible to rust diseases because of the monophyletic ('Petkus') origin of 1RS. Here we report and discuss the production and detailed investigation of a new T1BL.1RS translocation line carrying 1RS with widened genetic base originating from Secale cereanum. Line '179' exhibited improved spike morphology traits, resistance against stripe rust and leaf rust, as well as higher tillering capacity, fertility and dietary fiber (arabynoxylan) content than the parental wheat genotype. Comparative analyses based on molecular cytogenetic methods and molecular (SSR and DArTseq) makers indicate that the 1RS arm of line '179' is a recombinant of S. cereale and S. strictum homologues, and approximately 16% of its loci were different from that of 'Petkus' origin. 162 (69.5%) 1RS-specific markers were associated with genes, including 10 markers with putative disease resistance functions and LRR domains found on the subtelomeric or pericentromeric regions of 1RS. Line '179' will facilitate the map-based cloning of the resistance genes, and it can contribute to healthy eating and a more cost-efficient wheat production.

Figure 1

Stripe rust infection in the high-input PB nursery (Martonvásár, 2014). (a) severely infected leaf of the parental wheat line Mv9kr1; (b) infected leaf of the T1BL.1RS cultivar Mv Magdaléna; (c,d) leaves without any symptome of the parental perennial rye S. cereanum cultivar Kriszta and the Mv9kr1-‘Kriszta’ (wheat-S. cereanum) line ‘179’, respectively.

Figure 2

Cytomolecular identificaion of the line ‘179’. (a) Simultaneous FISH with DNA sequences (pSc119.2 - green, Afa-family - red, pTa71 - orange) and GISH on mitotic chromosome spread of the Mv9kr1-‘Kriszta’ (wheat-S. cereanum) line ‘179’. T1BL.1RS chromosomes (arrowed) together with a pair of ‘Mv9kr1 1B chromosomes are enlarged at the bottom-left corner. Double pSc119.2 pattern specific for 1RS of line ‘179’ is indicated by green arrowheads. Red GISH signal is visibile on the 1RS chromosome arm. Scale bar: 10 µm. (b) Spike morphology of the wheat lines ‘179’ and Mv9kr1.

Figure 3

Artificial leaf rust (Puccinia triticina) (a–d) and powdery mildew (Blumeria graminis f.sp. tritici; isolate LH07–14) (e–h) resistance tests. (a and e) Infected leaves of the parental wheat genotype Mv9kr1. (b and f) Resistant leaves of the parental perennial rye ‘Kriszta’. (c) Seedling of line ‘179’ showing hypersensitive response to the infection. One of the yellow necrotic spots is indicated with arrowhead. (g) Infected leaf of the T1BL.1RS traslocation line ‘179’ susceptible to powdery mildew. (d and h) Leaves of the susceptible ‘Mv Magdaléna’ (carrying 1RS from ‘Petkus’ rye). Experiments were carried out on 10-day-old seedlings under greenhouse conditions.

Figure 4

Morphology and FISH hybridization pattern of 1RS chromosome arms of different origin. Upper row (from left to right): DAPI-stained T1BL.1RS translocation chromosome of the wheat cultivar Mv Magdaléna, that of the Mv9kr1-‘Kriszta’ progeny line ‘179’ (as well as ‘C5’ and ‘D5’), 1R chromosomes of rye genotypes ‘Kriszta’, ‘Várda’ and S. strictum ssp. anatolicum. Differences in the visibility of the secondary constriction (NOR) are indicated with white and red arrows. Lower row: FISH polymorphism with the DNA probe pSc119.2 (indicated with green arrows). Curly brackets indicate chromosome pairs from different plant individuals.

Figure 5

Genetic linkage maps for the rye chromosome arm 1RS of line ‘179’. (a) Distribution of the Silico- and SNP-DArT markers specific for the stripe rust resistant ‘179’. Markers linked to LRR domain are enclosed by black rectangles. (b) Distribution of 1RS-specific markers exhibiting allelic variation between ‘Kriszta’ and ‘Petkus’ (present in ‘Mv Magdaléna’) 1RS. 1RS and 1RL (lacking from the T1BL.1RS translocation) chromosome arms are indicated in blue and gray, respectively. The marker distance is expressed in centimorgans (cM) from the telomere of 1RS (0 cM) to the putative centromere (60.72 cM) of chromosome 1R. *SNP-DArT markers.

Figure 6

Functional annotation of 1RS-specific and gene-associated DArTseq markers. (a) Pfam high-level grouping- and (b) Gene Ontology-based functional annotation of 203 Silico- and 30 SNP-DArT markers. Figures present groups with at least 3 members. The complete datasets are available in the Supplementary Data S2.