Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2010
Publication Date: November 28, 2010
Citation: Wang, R., Larson, S.R., Jensen, K.B. 2010. Analyses of Thinopyrum bessarabicum, Th. elongation and Th. junceum chromosomes using EST-SSR markers. Genome. 53:1083-1089. Interpretive Summary: The genus Thinopyrum contains important forage grasses, such as intermediate and tall wheatgrasses, that also serve as valuable gene pool for wheat improvement. The wheat disomic addition lines carrying individual Thinopyrum chromosomes are excellent research tools to study the structural arrangements and changes among chromosomes of different Thinopyrum species or genomes. The availability of two complete sets of wheat disomic addition lines for the diploid species Th. bessarabicum and Th. elongatum enables us to investigate individual chromosomes of hexaploid Th. junceum using the molecular markers for another genus, Leymus, in the tribe Triticeae that we developed. The Leymus EST-SSR marker system is proven useful in the comparative genomic study. The identity of Th. junceum chromosomes in 13 disomic wheat addition lines has been established. The information will facilitate future gene mapping and introgression works.
Technical Abstract: Wild Thinopyrum grasses serve as important gene pools for forage and cereal crops. Knowledge of their chromosome organizations is pivotal for efficient utilization of this important gene pool in germplasm enhancement programs. EST-SSR markers for Th. bessarabicum, Th. elongatum and Th. junceum chromosomes were identified among amplicons produced from 3 series of wheat-Thinopyrum addition lines using 193 primer pairs designed from the Leymus EST unigenes. The homology of Th. junceum chromosomes in respective wheat addition lines was established to reveal that homologous groups 3, 4, 5, 6 and 7 were represented by HD3515, HD3505, AJDAj11, AJDAj1, and HD3508, while groups 1 and 2 were represented by AJADj7 to AJDAj9 and AJDAj2 to AJDAj4, respectively. AJDAj5 and AJDAj6 had complexly reconstituted Th. junceum chromosomes that might have resulted from fusion or translocations of large chromosomal segments from 2 or more chromosomes, i.e. (1+5) and (2+5+1), respectively. The identified EST-SSR markers will be useful in comparative gene mapping, chromosome tracing, taxonomic studies, gene introgression, and cultivar identification.