Development and Characterization of a Novel Wheat–Tetraploid Thinopyrum elongatum 6E (6D) Disomic Substitution Line with Stripe Rust Resistance at the Adult Stage

Abstract

Stripe rust, which is caused by Puccinia striiformis f. sp. tritici, is one of the most devastating foliar diseases of common wheat worldwide. Breeding new wheat varieties with durable resistance is the most effective way of controlling the disease. Tetraploid Thinopyrum elongatum (2n = 4x = 28, EEEE) carries a variety of genes conferring resistance to multiple diseases, including stripe rust, Fusarium head blight, and powdery mildew, which makes it a valuable tertiary genetic resource for enhancing wheat cultivar improvement. Here, a novel wheat–tetraploid Th. elongatum 6E (6D) disomic substitution line (K17-1065-4) was characterized using genomic in situ hybridization and fluorescence in situ hybridization chromosome painting analyses. The evaluation of disease responses revealed that K17-1065-4 is highly resistant to stripe rust at the adult stage. By analyzing the whole-genome sequence of diploid Th. elongatum, we detected 3382 specific SSR sequences on chromosome 6E. Sixty SSR markers were developed, and thirty-three of them can accurately trace chromosome 6E of tetraploid Th. elongatum, which were linked to the disease resistance gene(s) in the wheat genetic background. The molecular marker analysis indicated that 10 markers may be used to distinguish Th. elongatum from other wheat-related species. Thus, K17-1065-4 carrying the stripe rust resistance gene(s) is a novel germplasm useful for breeding disease-resistant wheat cultivars. The molecular markers developed in this study may facilitate the mapping of the stripe rust resistance gene on chromosome 6E of tetraploid Th. elongatum.

Development, identification, and utilization of wheat–tetraploid Thinopyrum elongatum 4EL translocation lines resistant to stripe rust

“…The sample was cooled on ice for 5 min, after which 3 µL CS DNA was added. The solution was mixed and added to the slides, which were covered with coverslips, heated at 85 °C for 5 min, and incubated overnight at 50 °C (Gong et al 2023). The slides were immersed in 2× SSC and incubated at 50 °C water bath for 10 min.…”

“…After the GISH analysis, the slides were recycled as previously described (Gong et al 2023) before adding the Oligo-pSc119.2 and Oligo-pTa535 FISH probes to determine the chromosomal composition of the translocation lines. The FISH analysis was conducted as described by Li et al (2019).…”

Introgression of tetraploid Thinopyrum elongatum 6EL segments enhances the stripe rust resistance of adult wheat plants

“…The wheat-tetraploid Th. elongatum 6E (6D) substitution line K17-1065-4, which is highly resistant to stripe rust at the adult stage, was derived from the 8801/SM482//SM921 F 5 progeny (Gong et al 2023).…”

“…We previously developed 33 pairs of SSR markers for 6E on the basis of the whole-genome sequence of diploid Th. elongatum (Gong et al 2023). In the present study, we used the whole-genome sequence of diploid Th.…”

“…We previously developed a wheat-tetraploid Th. elongatum 1E (1D) substitution line resistant to stripe rust, a 3E (3D) substitution line tolerant to salt stress, a 4E (4D) substitution line resistant to stripe rust and powdery mildew, and 6E (6D) substitution lines resistant to stripe rust at the adult stage (Li et al 2019;Gong et al 2022;Gong et al 2023;Zeng et al 2023). However, the decreased fertility and genetic unpredictability of amphiploid, addition, and substitution lines make them inappropriate for commercial cultivation.…”