Homoeology of Thinopyrum distichum single chromosome additions in triticale and wheat

Authors: MARAIS, FRANCOIS - North Dakota State University; Fiedler, Jason; TAO, HONGBIN - North Dakota State University; PIRSEYEDI, SEVED - Arizona Plant Breeders Inc; HEGSTAD, JUSTIN - North Dakota State University; GANAPARTHI, VENKATA - North Dakota State University; LIU, YUAN - North Dakota State University; BISEK, BRADLEY - North Dakota State University; LI, XUEHUI - North Dakota State University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2020
Publication Date: 12/28/2020
Citation: Marais, F., Fiedler, J.D., Tao, H., Pirseyedi, S., Hegstad, J., Ganaparthi, V., Liu, Y., Bisek, B., Li, X. 2020. Homoeology of Thinopyrum distichum single chromosome additions in triticale and wheat. Crop Science. https://doi.org/10.1002/csc2.20357.
DOI: https://doi.org/10.1002/csc2.20357

Interpretive Summary: Sea wheatgrass (Thinopyrum distichum) is a perennial grass that inhabits harsh and dry saline coastal dunes. This grass is related to wheat, and specific genes in sea wheatgrass could potentially be used to improve drought, salt, and disease resistance in wheat. Previously, several cross hybridizations between wheatgrass and wheat or triticale were made, and progeny lines that contain a single added wheatgrass chromosome along with the full complement of wheat or triticale chromosomes were identified. In this study, we used genetic analysis to determine which wheatgrass chromosome was present in each line and to consolidate the 27 individual chromosome addition lines into 11 groups that each represent a single wheatgrass chromosome. Genetic comparisons among wheat and the related grasses revealed ancestral relationships among certain chromosomes which allowed the assignment of appropriate names to each wheatgrass chromosome in the unique addition lines. These results are useful for breeders and researchers looking to utilize these lines to identify new genes for resistance to drought, salt, or disease in grasses that may be deployed to breed new cultivars with improved traits.

Technical Abstract: Thinopyrum distichum (Thunb.) Löve inhabits harsh and dry saline coastal dunes. Its adaptive genes can be of value to cultivated cereals; therefore, single chromosome additions were developed in hexaploid triticale (×Triticosecale Wittm. ex A. Camus) and common wheat (Triticum aestivum L.), yet their homoeology to triticale and wheat chromosomes remained largely unknown. Genotyping by sequencing (GBS) was used to supplement conventional markers and facilitate synteny comparisons. Twenty-seven triticale additions, five of which have previously been determined to carry different Thinopyrum chromosomes, were analyzed first. GBS yielded 2.75 million unique sequences that included 134,506 Thinopyrum-specific tags, absent in wheat, durum, triticale and rye controls. The five distinct additions were used to initiate separation of the Thinopyrum-specific tags into 125,262 informative, single-pair tags (belonging to one homoeologous group) and 9,244 uninformative, multi-group tags associated with more than one homoeologous group. Presence-absence patterns produced by the single-pair tags revealed homologies, reducing the group from 27 to 11. Sequence tags associated with the 11 individual addition chromosomes were then aligned to the Th. elongatum and Chinese Spring genomic databases to reveal their homoeology. Five prominent translocations were present and three Thinopyrum chromosomes (1J1d, 2J2d and 4J1d) are extensively restructured. The ten common wheat additions include five different Thinopyrum addition chromosomes that are also in the triticale set. The 11 Th. distichum addition chromosomes consist of homoeologous pairs 2Jd, 4Jd, 6Jd and 7Jd plus individual chromosomes 1J1d, 3J1d and 5J1d. This constitutes a very useful genetic resource for continued dissection of the Th. distichum genomes.