Development and Identification of a Novel Wheat–Thinopyrum scirpeum 4E (4D) Chromosomal Substitution Line with Stripe Rust and Powdery Mildew Resistance

Abstract

Stripe rust caused by Puccinia striiformis f. sp. tritici and powdery mildew caused by Blumeria graminis f. sp. tritici are devastating diseases of wheat worldwide. Exploration of new disease-resistant genes from cultivated wheat and wild relatives are the most effective means of reducing the amounts of fungicides applied to combat these diseases. Thinopyrum scirpeum (2n = 4x = 28, EEEE) is an important promising reservoir of useful genes, including stripe rust and powdery mildew resistance, and may be useful for enhancing wheat disease resistance. Here, we characterize a novel wheat–Th. scirpeum disomic substitution line, K16-730-3, and chromosome-specific markers were developed that can be used to trace the Th. scirpeum chromosome or chromosome segments transferred into wheat. Genomic in situ hybridization and fluorescence in situ hybridization analyses indicated that K16-730-3 is a new 4E (4D) chromosomal substitution line. Evaluation of seedling and adult disease responses revealed that K16-730-3 is resistant to stripe rust and powdery mildew. In addition, no obvious difference in grain yield was observed between K16-730-3 and its wheat parents. Genotyping-by-sequencing analyses indicated that 74 polymerase chain reaction -based markers can accurately trace chromosome 4E which were linked to the disease resistance genes in the wheat background. Further marker validation analyses revealed that 13 specific markers can distinguish between the E-genome chromosomes of Th. scirpeum and the chromosomes of other wheat-related species. The new substitution line K16-730-3 carrying the stripe rust and powdery mildew resistance genes will be useful as novel germplasm in breeding for disease resistance. The markers developed in this study can be used in marker-assisted selection for improvement of disease resistance in wheat.

Cytogenetic and Molecular Marker Analyses of a Novel Wheat–Psathyrostachys huashanica 7Ns Disomic Addition Line with Powdery Mildew Resistance

“…Molecular markers have been extensively applied to quickly and accurately trace alien chromosomes or chromosomal segments in a wheat background, in turn greatly improving the selection efficiency of marker-assisted breeding and shortening the breeding cycle [ 52 ]. An increasing number of potentially beneficial genes have been gradually identified in P. huashanica , but the lack of specific, stable, efficient, and reliable molecular markers imposes significant restrictions on their further utilization in breeding [ 53 ]. The development of molecular markers specific for P. huashanica is thus important and urgently needed to facilitate future research efforts.…”

“…As another example, we previously used SLAF-seq technology to develop 45 markers specific for one arm of P. huashanica chromosome 7Ns to efficiently identify 7Ns chromosome segments carrying earliness per se genes in a wheat background [ 25 ]. Compared with the above-mentioned technologies, GBS is a simpler, more robust, and more cost-effective approach [ 60 ]; it is also more suitable for the development of large-scale molecular markers in Triticeae species without reference genome sequences, such as for tetraploid Thinopyrum elongatum chromosomes 1E and 4E [ 53 , 61 ]. The use of GBS for the development of P. huashanica -specific molecular markers has not been reported until now, and the number of existing markers has also been totally insufficient to satisfy research demands.…”

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

“…The samples were denatured at 85 • C for 5 min and then incubated overnight at 50 • C. They were subsequently washed with 2× SSC at 50 • C for 20 min and then with 75%, 95%, and 100% ethanol for 1 min each. The chromosome counterstaining and the slide microscopy were performed as described by Gong et al [35].…”

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

“…The speci c SSR primers for chromosome 6EL were selected and synthesized at Sangon Biotech (Chengdu, China). The validity of the primers was veri ed by PCR as described by Gong et al (2022). Primers that ampli ed the target sequence in 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.…”