The Aegilops ventricosa 2NvS segment in bread wheat: cytology, genomics and breeding

Abstract

Key message The first cytological characterization of the 2NvS segment in hexaploid wheat; complete de novo assembly and annotation of 2NvS segment; 2NvS frequency is increasing 2NvS and is associated with higher yield. Abstract The Aegilops ventricosa 2NvS translocation segment has been utilized in breeding disease-resistant wheat crops since the early 1990s. This segment is known to possess several important resistance genes against multiple wheat diseases including root knot nematode, stripe rust, leaf rust and stem rust. More recently, this segment has been associated with resistance to wheat blast, an emerging and devastating wheat disease in South America and Asia. To date, full characterization of the segment including its size, gene content and its association with grain yield is lacking. Here, we present a complete cytological and physical characterization of this agronomically important translocation in bread wheat. We de novo assembled the 2NvS segment in two wheat varieties, ‘Jagger’ and ‘CDC Stanley,’ and delineated the segment to be approximately 33 Mb. A total of 535 high-confidence genes were annotated within the 2NvS region, with > 10% belonging to the nucleotide-binding leucine-rich repeat (NLR) gene families. Identification of groups of NLR genes that are potentially N genome-specific and expressed in specific tissues can fast-track testing of candidate genes playing roles in various disease resistances. We also show the increasing frequency of 2NvS among spring and winter wheat breeding programs over two and a half decades, and the positive impact of 2NvS on wheat grain yield based on historical datasets. The significance of the 2NvS segment in wheat breeding due to resistance to multiple diseases and a positive impact on yield highlights the importance of understanding and characterizing the wheat pan-genome for better insights into molecular breeding for wheat improvement.

Genome‐wide association reveals limited benefits of pyramiding the 1B and 1D loci with the 2NvS translocation for wheat blast control

“…Pooled GBS libraries were sequenced using Illumina HiSeq2500 equipment. Single nucleotide polymorphisms (SNPs) were called using Tassel 5.0 (Glaubitz et al., 2014). The physical positions of SNP markers were corrected based on the reference genome 161010_Chinese_Spring_v1.0 (IWGSC et al., 2018).…”

Detecting Major Introgressions in Wheat and their Putative Origins Using Coverage Analysis

“…SY Mattis, with Aegilops comosa (2n=2x=14, M) and Aegilops uniaristata (2n=2x=14, N) identified as the putative diploid donors (Figure 3). It is known from their pedigree that these four cultivars harbour an introgression from tetraploid Aegilops ventricosa (2n=4x=28, DN) [35][36][37] , which shares the N subgenome with Ae. uniaristata 38 .…”

Genetic Characterization and Curation of Diploid A-Genome Wheat Species

“…Several accessions were donated by Robert Metzger, USDA, Oregon State University, Corvallis (26), seven were collected by the WGRC, and the remainder (10) from other sources. We also tested 225 CIMMYT wheat lines (Supplementary Table S1) genotyped earlier with GBS SNPs (Gao et al, 2021) thereby inferring the genetic relationships between A-genome diploids and the wheat.…”

“…We sequenced on the Illumina platform with 150 bp pair-end reads (PE150). We had total The information about GBS of 226 CIMMYT lines can be obtained (Gao et al, 2021).…”