Homoeology of Thinopyrum distichumsingle‐chromosome additions in triticale and wheat

Thinopyrum distichum(Thunb.) Á. Löve (2n= 4x= 28; J1dJ1dJ2dJ2d) inhabits harsh, dry saline coastal dunes. Its adaptive genes can be of value to cultivated cereals; therefore, single‐chromosome additions were previously developed in hexaploid triticale (×TriticosecaleWittm. ex A. Camus) and common wheat (Triticum aestivumL.); however, their homoeology to triticale and wheat chromosomes remained largely unknown. Here we used genotyping‐by‐sequencing (GBS) to supplement conventional markers and determine the synteny of the Th. distichumaddition chromosomes. Twenty‐seven triticale lines with single Th. distichumaddition chromosomes were analyzed. Genotyping‐by‐sequencing yielded 2.75 million unique sequences that included 134,506 Th. distichum‐specific tags absent in the wheat, durum wheat [Triticum turgidumL. subsp. Durum(Desf.) van Slageren], ×Triticosecalespp., and rye (Secale cerealeL.) controls. The Th. distichum‐specific tags were then sorted into 125,262 informative, single‐pair tags (from 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 suggested the presence of 11 different Th. distichumaddition chromosomes whose associated sequence tags were then aligned to the Th. elongatum(Host) D. R. Dewey and Chinese Spring (CS) genomic databases to reveal their homoeology. Five prominent translocations were detected among the 11 Th. distichumaddition chromosomes and three chromosomes appeared to be extensively restructured. The extra chromosomes in 10 additions to common wheat represented five different Th. distichumchromosomes that were also represented in the triticale set. The 11 distinct Th. distichumaddition chromosomes constitute a useful genetic resource for continued dissection of the Th. distichumgenomes.