Abstract
Fusarium head blight (FHB), leaf rust, and stem rust are the most destructive fungal diseases in current world wheat production. The diploid wheatgrass, Thinopyrum elongatum (Host) Dewey (2n = 2x = 14, EE) is an excellent source of disease resistance genes. Two new Triticum–Secale–Thinopyrum trigeneric hybrids were derived from a cross between a hexaploid triticale (X Triticosecale Wittmack, 2n = 6x = 42, AABBRR) and a hexaploid Triticum trititrigia (2n = 6x = 42, AABBEE), were produced and analyzed using genomic in situ hybridization and molecular markers. The results indicated that line RE21 contained 14 A-chromosomes, 14 B-chromosomes, three pairs of R-chromosomes (4R, 6R, and 7R), and four pairs of E-chromosomes (1E, 2E, 3E, and 5E) for a total chromosome number of 2n = 42. Line RE62 contained 14 A-chromosomes, 14 B-chromosomes, six pairs of R-chromosomes, and one pair of translocation chromosomes between chromosome 5R and 5E, for a total chromosome number of 2n = 42. At the seedling and adult growth stages under greenhouse conditions, line RE21 showed high levels of resistance to FHB, leaf rust, and stem rust race Ug99, and line RE62 was highly resistant to leaf rust and stem rust race Ug99. These two lines (RE21 and RE62) display superior disease resistance characteristics and have the potential to be utilized as valuable germplasm sources for future wheat improvement.
Highlights
Fusarium head blight (FHB), caused by Fusarium graminearum, F. culmorum, and other Fusarium species, is one of the most destructive fungal world diseases in wheat production
Stem rust is caused by P. graminis f. sp. tritici (Pgt) and is an economically impactful disease of wheat that can be controlled by using effective stem rust resistance (Sr) genes
Singh et al (2011) heeded Dr Norman Borlaug’s warning in 2005 that stem rust race Ug99 could spread throughout the world wheat production areas, leading to worldwide food shortages, because approximately 85–95% of globally distributed common wheat cultivars are susceptible to stem rust race Ug99
Summary
Fusarium head blight (FHB), caused by Fusarium graminearum, F. culmorum, and other Fusarium species, is one of the most destructive fungal world diseases in wheat production. Recent investigations of several other wild relatives of wheat, such as diploid wheatgrass Leymus racemosus, Th. intermedium, Th. elongatum, and tetraploid wheatgrass Th. junceiforme, have been shown to be highly resistant to FHB (Chen et al, 2005; Becher et al, 2013; Kalih et al, 2014). Various strategies have been developed to control leaf rust, the most economical and effective of which has been to use new resistance resources of cultivated germplasm (Chu et al, 2009). Tritici (Pgt) and is an economically impactful disease of wheat that can be controlled by using effective stem rust resistance (Sr) genes. For economic and environmentally sustainable disease control, Ug99-resistant wheat varieties should be developed from cultivated germplasm or wild related species. For economic and environmentally sustainable disease control, Ug99-resistant wheat varieties should be developed from cultivated germplasm or wild related species. Zeng et al (2013) obtained translocation lines from the Ee and St genomes of Th. intermedium, and these lines have shown good resistance to leaf rust and stem rust race Ug99
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