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 Js 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 1Js. Thus, CH10A5 was a wheat–Th. ponticum 1Js (1D) disomic substitution line. Field disease resistance trials demonstrated that the introduced Th. ponticum chromosome 1Js 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 1Js 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.
Highlights
Epidemics of stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), occur frequently in areas with cool conditions during the wheat growing season
A total of 177 pollen mother cells (PMCs) were assessed over a 3-year period, of these 169 PMCs were observed 21 pairs of bivalents in meiotic metaphase I in (Figure 1B), up to 95.48%, and univalents were observed in 8 PMCs (4.52%), and on trivalents and quadrivalents were observed
CH10A5 is a novel 1Js (1D) disomic substitution line derived from a cross between common wheat 7182 and Th. ponticum
Summary
Epidemics of stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), occur frequently in areas with cool conditions during the wheat growing season. Epidemics of stripe rust, caused by Puccinia striiformis f. Tritici (Pst), occur frequently in areas with cool conditions during the wheat growing season. Tritici (Bgt) (An et al, 2019). Powdery mildew is caused by Blumeria graminis (DC.) E.O.f. sp. These two major diseases can dramatically reduce crop yield during prevalent years (Bokore et al, 2017). Numerous powdery mildew and stripe rust resistance genes have been identified in wheat and its relatives, and these genes have played a fundamental role in wheat breeding (Liu et al, 2019). It is extremely important to identify new resistance genes, especially broad-spectrum resistance genes, from wheat-related species
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