Molecular cytogenetic characterization of a new wheat-rye 1BL•1RS translocation line expressing superior stripe rust resistance and enhanced grain yield

Abstract

A new wheat-rye 1BL•1RS translocation line, with the characteristics of superior stripe rust resistance and high thousand-kernel weight and grain number per spike, was developed and identified from progenies of wheat-rye- Psathyrostachys huashanica trigeneric hybrids. The wheat-rye 1BL•1RS translocation line from Petkus rye has contributed substantially to the world wheat production. However, due to extensive growing of cultivars with disease resistance genes from short arm of rye chromosome 1R and coevolution of pathogen virulence and host resistance, these cultivars successively lost resistance to pathogens. In this study, a new wheat-rye line K13-868, derived from the progenies of wheat-rye-Psathyrostachys huashanica trigeneric hybrids, was identified and analyzed using fluorescence in situ hybridization (FISH), genomic in situ hybridization (GISH), acid polyacrylamide gel electrophoresis (A-PAGE), and molecular markers. Cytological studies indicated that the mean chromosome configuration of K13-868 at meiosis was 2n = 42 = 0.14 I + 18.78 II (ring) + 2.15 II (rod). Sequential FISH and GISH results demonstrated that K13-868 was a compensating wheat-rye 1BL•1RS Robertsonian translocation line. Acid PAGE analysis revealed that clear specific bands of rye 1RS were expressed in K13-868. Simple sequence repeat (SSR) and rye 1RS-specific markers ω-sec-p1/ω-sec-p2 and O-SEC5'-A/O-SEC3'-R suggested that the 1BS arm of wheat had been substituted by the 1RS arm of rye. At the seedling and adult growth stage, compared with its recurrent wheat parent SM51 and six other wheat cultivars containing the 1RS arm in southwestern China, K13-868 showed high levels of resistance to stripe rust (Puccinia striiformis f. sp. tritici, Pst) pathogens prevalent in China, which are virulent to Yr10 and Yr24/Yr26. In addition, K13-868 expresses higher thousand-kernel weight and more grain number per spike than these controls in two growing seasons, suggesting that this line may carry yield-related genes of rye. This translocation line, with significant characteristics of resistance to stripe rust and high thousand-kernel weight and grain number per spike, could be utilized as a valuable germplasm for wheat improvement.

Molecular Cytogenetic Characterization of Novel Wheat-rye T1RS.1BL Translocation Lines with High Resistance to Diseases and Great Agronomic Traits

“…These new T1RS.1BL translocation lines showed diversity-resistant patterns to rust stripe and powdery mildew. However, few new translocation lines showed both high resistance to these two diseases and could be used in the wheat breeding program (Ko et al, 2002; Yang et al, 2014; Li et al, 2016b; Qi et al, 2016). …”

“…Since the 1990s, due to its single origin, the 1RS chromosome arm derived from Petkus rye has not provided protection against the prevalence of virulent pathogens (Shi et al, 2001; Ren et al, 2009). So far, only a few other sources of 1RS were transferred into wheat (Ko et al, 2002; Mater et al, 2004; Ren et al, 2009, 2012; Molnár-Láng et al, 2010; Yang et al, 2014; Li et al, 2016a,b; Qi et al, 2016), and not every new translocation line could be used in wheat breeding programs (Ren et al, 2012). For more efficient use of the T1RS.1BL translocation in wheat breeding, Ren et al (2012) suggested introduce a large amount of new genetic variation from many different rye sources into wheat.…”

Molecular Cytogenetic Characterization of two Triticum–Secale–Thinopyrum Trigeneric Hybrids Exhibiting Superior Resistance to Fusarium Head Blight, Leaf Rust, and Stem Rust Race Ug99

“…Trigeneric hybrids seem to be less promising as potential crop, but they could be a useful bridge for the transference of chromatin into cultivated wheat. For example, Qi et al (2016) produced a new wheat-rye- Psathyrostachys trigeneric hybrid carrying the wheat-rye 1BL•1RS translocation and a cryptic translocation involving a small chromosome segment with the stripe rust resistance gene from P. huashanica . In this study, we developed two Triticum–Secale–Thinopyrum hexaploid lines that carried resistance genes against FHB, leaf rust, and stem rust race Ug99.…”

“…Wild relatives of common wheat, which have superior agronomic traits and resistance to biotic and abiotic stresses, are often used as desirable gene donors in wheat breeding programs (Dong et al, 1992; Mujeeb-Kazi et al, 2013). To date, many genes from wild species conferring superior traits have been transferred into cultivated wheat by developing newly synthesized allopolyploids (Qi et al, 2016). For example, breeders developed a man-made crop, triticale (X Triticosecale Wittmack), by crossing wheat ( T. turgidum or T. aestivum ) and rye.…”

Cytogenetics and stripe rust resistance of wheat–Thinopyrum elongatum hybrid derivatives

“…Wild relatives of common wheat display numerous desirable agronomic traits, including strong adaptability, resistance to biotic and abiotic stress, and high-quality of wheat, and might thus potentially enrich the genetic repertoire of domesticated wheat species [4, 5]. Distant hybridization is a commonly used approach to modify the genetic background of common wheat in order to introduce the beneficial traits of wild species into the genome of domestic wheat [6, 7]. To date, numerous related species from the tribe Triticeae , including those from genera Aegilops , Agropyron , Dasypyrum , Hordeum , Leymus , Lophopyrum , Psathyrostachys , Secale , and Thinopyrum , have been successfully crossed with wheat, and the resulting cultivars have contributed significantly to wheat production worldwide [8–13].…”