Molecular cytogenetics and development of St-chromosome-specific molecular markers of novel stripe rust resistant wheat–Thinopyrum intermedium and wheat–Thinopyrum ponticum substitution lines

Abstract

Background Owing to their excellent resistance to abiotic and biotic stress, Thinopyrum intermedium (2n = 6x = 42, JJJsJsStSt) and Th. ponticum (2n = 10x = 70) are both widely utilized in wheat germplasm innovation programs. Disomic substitution lines (DSLs) carrying one pair of alien chromosomes are valuable bridge materials for transmission of novel genes, fluorescence in situ hybridization (FISH) karyotype construction and specific molecular marker development. Results Six wheat–Thinopyrum DSLs derived from crosses between Abbondanza nullisomic lines (2n = 40) and two octoploid Trititrigia lines (2n = 8x = 56), were characterized by sequential FISH–genome in situ hybridization (GISH), multicolor GISH (mc-GISH), and an analysis of the wheat 15 K SNP array combined with molecular marker selection. ES-9 (DS2St (2A)) and ES-10 (DS3St (3D)) are wheat–Th. ponticum DSLs, while ES-23 (DS2St (2A)), ES-24 (DS3St (3D)), ES-25(DS2St (2B)), and ES-26 (DS2St (2D)) are wheat–Th. intermedium DSLs. ES-9, ES-23, ES-25 and ES-26 conferred high thousand-kernel weight and stripe rust resistance at adult stages, while ES-10 and ES-24 were highly resistant to stripe rust at all stages. Furthermore, cytological analysis showed that the alien chromosomes belonging to the same homoeologous group (2 or 3) derived from different donors carried the same FISH karyotype and could form a bivalent. Based on specific-locus amplified fragment sequencing (SLAF-seq), two 2St-chromosome-specific markers (PTH-005 and PTH-013) and two 3St-chromosome-specific markers (PTH-113 and PTH-135) were developed. Conclusions The six wheat–Thinopyrum DSLs conferring stripe rust resistance can be used as bridging parents for transmission of valuable resistance genes. The utility of PTH-113 and PTH-135 in a BC1F2 population showed that the newly developed markers could be useful tools for efficient identification of St chromosomes in a common wheat background.

Introgression of Agropyron cristatum genes to counteract the negative relationship between grain number and grain weight of wheat

“…ponticum 2A/2St and wheat-Th. intermedium 2B/2St disomic substitution lines in the common wheat background increased TGW (Zhang et al 2015b;Feng et al 2021;Wang et al 2022a). However, a few high-yield alien genes are directly used for breeding high-yielding wheat today, because of the genetic burden and the negative relationship between GNS and TGW.…”

Development and cytological characterization of wheat–Thinopyrum intermedium translocation lines with novel stripe rust resistance gene

“…It was reported that several stripe rust resistance genes have been mapped on the different St chromosomes of Th. intermedium, including chromosomes 1St, 2St, 3St, and 7St (Hu et al, 2011;Song et al, 2013;Nie et al, 2019;Wang et al, 2022). Except for the St subgenome, the subgenome J or J s has also been proven to carry the resistance genes for stripe rust.…”

Molecular cytogenetic characterization of a new wheat-Thinopyrum intermedium homoeologous group-6 chromosome disomic substitution line with resistance to leaf rust and stripe rust

“…With the rapid development of sequencing technologies, SNP array analysis is becoming increasingly popular in high-throughput genotyping wheat and wild relatives because of its high-density loci and reasonable cost ( Winfield et al, 2016 ). Recently, SNP arrays also play a vital role in detecting the homoeologous relationships between wheat and alien chromosomes in wheat-alien introgression lines ( Li et al, 2019b ; Wang et al, 2020 , 2022 ). In this study, results from the wheat 55K SNP array showed that chromosome 6B had the highest percentage of polymorphic SNP loci between CH51 and wheat parent Jintai 170 ( Figure 2 and Table 1 ) and also had the highest percentage (62.82%) of missing SNP loci in CH51 ( Supplementary Table 1 ).…”