A genetic map of Lophopyrum ponticum chromosome 7E, harboring resistance genes to Fusarium head blight and leaf rust

Abstract

The leaf rust resistance gene Lr19 and Fusarium head blight (FHB) resistance quantitative trait loci (QTL) derived from the wild wheatgrass Lophopyrum ponticum have been located on chromosome 7E. The main objectives of the present study were to develop a genetic map of chromosome 7E and map the two resistance loci using a population of 237 F(7:8) recombinant inbred lines (RILs) derived from a cross between two Thatcher-L. ponticum substitution lines, K11463 (7el(1)(7D)) and K2620 (7el(2)(7D)). 532 G-SSR, E-SSR and STS markers from wheat chromosome group 7 were screened in the parent lines. Of these, 118 markers were polymorphic, with a polymorphism frequency of 22.2%. A genetic map of L. ponticum chromosome 7E was constructed with 64 markers, covering 95.76 cM, with an average genetic distance of 1.47 cM between markers. The major FHB resistance locus, temporarily assigned as FhbLoP, was mapped to the very distal region of the long arm of chromosome 7E within a 3.71 cM interval flanked by Xcfa2240 and Xswes19, which accounts for 30.46% of the phenotypic variance. Lr19 was bracketed by Xwmc273 and XBE404744, with a map distance of 1.54 and 1.43 cM from either side, respectively. The closely linked markers identified in this study will be helpful for marker-assisted introgression of the L. ponticum-derived FhbLoP and Lr19 genes into elite cultivars of wheat, and the development of a genetic map will accelerate the map-based cloning of these two genes.

Harnessing Genetic Diversity of Wild Gene Pools to Enhance Wheat Crop Production and Sustainability: Challenges and Opportunities

“…Similarly, and in this case exploiting the high degree of homology relating two group 7 chromosomes (named 7el 1 and 7el 2 ) of different Th. ponticum accessions, the Lr19 gene (located on the 7el 1 L arm) was pyramided, both in bread wheat [39][40][41] and in durum wheat [41], with Fhb-7el2, a major QTL for resistance to Fusarium head blight (FHB) mapped on 7el 2 L (recently renamed Fhb7 [42]). …”

RAPD and ISSR-assisted identification and development of three new SCAR markers specific for the Thinopyrum elongatum E (Poaceae) genome

“…The major FHB resistance gene, Fhb1, was identified by Shen and Ohm (2006) from the homologous group 7, based on evaluation of a series of CS-T. elongatum chromosome substitution lines. A genetic map of chromosome 7E was developed and two resistance loci (leaf rust resistance gene Lr19 and FHB resistance QTL) were mapped to chromosome 7E by using a population of 237 F 7:8 recombinant inbred lines derived from a cross between two Thatcher-L. ponticum substitution lines (Zhang et al, 2011). The wheat stripe rust disease resistance gene YrE was located on chromosome 3E from T. elongatum, and the introduction of genes from the T. elongatum 3E has improved the resistance of common wheat to salinity stress (Ma et al, 1999).…”

Genomes, Chromosomes and Genes of the Wheatgrass Genus Thinopyrum: the Value of their Transfer into Wheat for Gains in Cytogenomic Knowledge and Sustainable Breeding

“…This can be partly due to the size difference between the wheat and alien arm 7el 1 L < 7AL, see above), and also to a possibly different structural organization leading to variations in marker/gene density. Data from genetic maps indicate the length of the entire 7el chromosome (95.76 cM in Zhang et al 2011) to be shorter than the consensus map of wheat 7A (131 cM in Somers et al 2004), with corresponding average genetic distances between markers of 1.47 cM vs. 2.1 cM, respectively ).…”