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

Thinopyrum ponticum(2n= 10x= 70), a member of the tertiary gene pool of wheat (Triticum aestivumL.), harbors many biotic and abiotic stress resistance genes. CH10A5, a novel disomic substitution line from a cross ofT. aestivumcv. 7182 andTh. ponticum, was characterized by cytogenetic identification,in situhybridization, 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. Genomein situhybridization (GISH) analysis indicated that two of its chromosomes came from the J(s)genome ofTh. ponticum, and wheat 15K array mapping and fluorescencein situhybridization (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. ponticum1J(s)(1D) disomic substitution line. Field disease resistance trials demonstrated that the introducedTh. ponticumchromosome 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 ofTh. 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.