Cytogenetic Analysis and Molecular Marker Development for a New Wheat–Thinopyrum ponticum 1Js (1D) Disomic Substitution Line With Resistance to Stripe Rust and Powdery Mildew

Abstract

Thinopyrum ponticum (2n = 10x = 70), a member of the tertiary gene pool of wheat (Triticum aestivum L.), harbors many biotic and abiotic stress resistance genes. CH10A5, a novel disomic substitution line from a cross of T. aestivum cv. 7182 and Th. ponticum, was characterized by cytogenetic identification, in situ hybridization, molecular marker analysis, and morphological investigation of agronomic traits and disease resistance. Cytological observations showed that CH10A5 contained 42 chromosomes and formed 21 bivalents at meiotic metaphase I. Genome in situ hybridization (GISH) analysis indicated that two of its chromosomes came from the J s genome of Th. ponticum, and wheat 15K array mapping and fluorescence in situ hybridization (FISH) revealed that chromosome 1D was absent from CH10A5. Polymorphic analysis of molecular markers indicated that the pair of alien chromosomes belonged to homoeologous group one, designated as 1J s. Thus, CH10A5 was a wheat-Th. ponticum 1J s (1D) disomic substitution line. Field disease resistance trials demonstrated that the introduced Th. ponticum chromosome 1J s was probably responsible for resistance to both stripe rust and powdery mildew at the adult stage. Based on specific-locus amplified fragment sequencing (SLAF-seq), 507 STS molecular markers were developed to distinguish chromosome 1J s genetic material from that of wheat. Of these, 49 STS markers could be used to specifically identify the genetic material of Th. ponticum. CH10A5 will increase the resistance gene diversity of wheat breeding materials, and the markers developed here will permit further tracing of heterosomal chromosome fragments in the future.

Molecular Cytogenetics and SLAF-seq-based Specific Molecular Markers for a Wheat–Aegilops geniculata 3M g Alien Addition Line with Resistance to Stripe Rust and Powdery Mildew

“…Markers speci c to Aegilops biuncialis were developed with a success rate of up to 40.33% [51]; The success rate of 1JS-speci c marker development from an alien chromosome of Th. ponticum was 52.98% [52]. The development of SLAF-seq technology has certain practical importance [32].…”

“…[56] used the Cbanding technique to show that chromosomal rearrangement had occurred in 208 tetraploid wheat, 252 hexaploid wheat, and 39 triticale accessions. The introduction of alien chromosomes may lead to changes in the structure of chromosomes of common wheat and affect the expression of a suite of genes [52,59]. Przewieslik-Allen et al [60] analyzed 471 materials and found that chromosome rearrangement plays an important role in the genetic diversity of varieties.…”

Stripe rust resistance gene Yr34 (synonym Yr48) is located within a distal translocation of Triticum monococcum chromosome 5AmL into common wheat

“…WAWHT2046, RIL143, Avocet-S and F 2 plants from the mapping population were grown in controlled walk-in growth chambers at 24 °C during the day and 22 °C during the night. At the jointing stage, plants were inoculated with fresh urediniospores of race CYR34 mixed with talcum powder at a 1:20 ratio using the shaking off method (Ma et al 2016 ; Wang et al 2020b ). Wheat leaves were uniformly dusted with this mixture of urediniospores and talc.…”

Molecular Cytogenetic Identification of a Novel Wheat–Thinopyrum ponticum 1JS (1B) Substitution Line Resistant to Powdery Mildew and Leaf Rust

“…A total of 914 markers (Table 1), including simple sequence repeat (SSR)/expressed sequence tag (EST), which belonged to the first homologous group (https://wheat.pw.usda.gov/ GG3/), intron targeting (IT) markers (Zhang et al, 2017), and PCR-based landmark unique gene (PLUG) markers (Wang et al, 2020), were synthesized by Sangon Biotech Co., Ltd. and used to identify the homeologous group of the alien chromosomes in SN19647 and compare their identity with those in CH10A5. PCR amplification system was a 10-µL reaction mixture, containing 40 ng genomic DNA, 2 µM each of forward and reverse primers, 2.5 mM each of the dNTPs, 2.5 mM MgCl 2 , 1× PCR buffer (10 mM Tris-HCl, pH 8.5, 50 mM KCl), and 0.5 U Taq DNA polymerase.…”

“…Recently, the 1J S chromosome of Th. ponticum in the 1J S (1D) disomic substitution line CH10A5 was reported to be probably responsible for resistance to both powdery mildew and stripe rust (Wang et al, 2020).…”