Dissection and physical mapping of wheat chromosome 7B by inducing meiotic recombination with its homoeologues in Aegilops speltoides and Thinopyrum elongatum

Authors: ZHANG, MINGYI - North Dakota State University; ZHANG, WEI - North Dakota State University; ZHU, XIANWEN - North Dakota State University; SUN, QING - North Dakota State University; YAN, CHANGHUI - North Dakota State University; Xu, Steven; Fiedler, Jason; CAI, XIWEN - North Dakota State University

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2020
Publication Date: 9/15/2020
Citation: Zhang, M., Zhang, W., Zhu, X., Sun, Q., Yan, C., Xu, S.S., Fiedler, J.D., Cai, X. 2020. Dissection and physical mapping of wheat chromosome 7B by inducing meiotic recombination with its homoeologues in Aegilops speltoides and Thinopyrum elongatum. Theoretical and Applied Genetics. https://doi.org/10.1007/s00122-020-03680-3.
DOI: https://doi.org/10.1007/s00122-020-03680-3

Interpretive Summary: Modern wheat improvement through breeding relies highly on the availability of elite lines carrying desirable genes for various agriculturally important traits such as pest and disease resistance, high yield, and improved quality. However, extensive breeding practices have resulted in the depletion of many useful genes from modern wheat lines. Wild relative species of wheat can serve as a good source of genes for agronomically-important traits that can be introduced into elite wheat lines by conventional means. In this study, we developed numerous wheat lines carrying segments of genetic material from wheat relatives known as goatgrass and tall wheatgrass. These wheat lines will serve as useful bridges for transferring the wild relative genes into modern lines. DNA markers specific for the wheatgrass and goatgrass segments were developed to allow further study of the genes and to serve as tools to facilitate efficient introduction of the genes into new wheat cultivars.

Technical Abstract: Homoeologous recombination leads to the dissection of the wheat genome and expansion of wheat genetic variability. Advances in genome sequencing and genotyping have dramatically improved the efficacy and throughput of homoeologous recombination-based genome study and alien introgression in wheat and its relatives. In this study, we aimed to physically dissect and map wheat chromosome 7B by inducing meiotic recombination of chromosome 7B with its homoeoloues 7E in Thinopyrum elongatum and 7S in Aegilops speltoides. The special genotypes, which were double monosomic for chromosomes 7B’+7E’ or 7B’+7S’ and homozygous for the ph1b mutant, were produced to enhance 7B-7E and 7B-7S recombination. Chromosome-specific DNA markers were developed and used to pre-screen large recombination populations for 7B-7E and 7B-7S recombinants. The marker-mediated pre-selections were verified by fluorescent genomic in situ hybridization (FGISH). Totally, 29 7B-7E and 61 7B-7S recombinants and multiple chromosome aberrations were recovered and delineated by FGISH and wheat 90K SNP assay. Integrated FGISH and SNP analysis of the recombinants physically mapped the recombination breakpoints and partitioned wheat chromosome 7B into 44 bins with 523 SNPs assigned in. A composite bin map was constructed for chromosome 7B, showing the bin size and physical distribution of SNPs. It provides a unique physical framework for further study of chromosome 7B and its homoeologues. In addition, the 7B-7E and 7B-7S recombinants extend the genetic variability of wheat chromosome 7B and represent useful germplasm for wheat breeding. Thereby, this genomics-enabled chromosome engineering approach facilitates wheat genome study and enriches the gene pool of wheat improvement.