Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 2012
Publication Date: April 11, 2012
Citation: Dou, Q.W., Lei, Y., Li, X., Mott, I.W., Wang, R. 2012. Characterization of alien chromosomes in backcross derivatives of Triticum aestivum x Elymus rectisetus hybrids using molecular markers and sequential multi-color FISH/GISH. Genome. 55:337-347. Interpretive Summary: It would be extremely difficult, if not completely impossible, to map any traits to chromosomes of the Australian apomictic Elymus rectisetus, a perennial Triticeae grass. We have obtained many stable fertile derivatives from hybrids between bread wheat and this grass. In this study, we determined the identities of alien grass chromosomes in five cytogenetic stocks of the bread wheat. It is concluded that the 1Y chromosome of E. rectisetus carries genes for resistance to tan spot and nodorum blotch. One line carries the 1St chromosome in addition to 21 pairs of wheat chromosomes. Two lines had 2A, 4B and 6D chromosomes of wheat substituted by three pairs of grass chromosomes, of which one was of the W genome and two of St. Another line differed from these two triple-substitution lines only by the additional pair of Y-genome chromosome. These lines are valuable plant materials for searching useful traits, locating molecular markers, and studying evolution of the transferred grass chromosomes from apomictic E. rectisetus.
Technical Abstract: Wild Triticeae grasses serve as important gene pools for forage and cereal crops. Based on DNA sequences of genome-specific RAPD markers, sequence tagged site (STS) markers specific for W and Y genomes have been obtained. Coupling with the use of genomic in situ hybridization (GISH), these STS markers enabled the identification of the W- and Y-genome chromosomes in backcross derivatives from hybrids of bread wheat Triticum aestivum L. (2n=42; AABBDD) and Elymus rectisetus (Nees in Lehm.) A. Love & Conner (2n = 42; StStWWYY). The detection of 6 different alien chromosomes in 5 of these derivatives was ascertained by reactions to wheat pathogens, qPCR of STS markers, simple sequence repeat (SSR) markers, and/or multi-color florescence in situ hybridization (FISH). Disomic addition line 4687 (2n=44) has the full complement of 42 wheat chromosomes and a pair of 1Y chromosome that carries genes for resistance to tan spot [caused by Pyrenophora tritici-repentis (Died.) Drechs.] and Stagonospora nodorum blotch (SNB) [caused by Stagonospora nodorum (Berk.) Castellani and Germano]. The disomic addition line 4162 has a pair of 1St chromosome and 21 pairs of wheat chromosomes. Lines 4319 and 5899 are two triple substitution lines (2n=42) having the same chromosome composition, with 2A, 4B and 6D substituted by one pair of W- and two pairs of St-genome chromosomes. Line 4434 is a substitution-addition line (2n=44) that differs from lines 4319 and 5899 only by having a pair of Y-genome chromosome, which is different from the one in line 4687. The production and identification of these alien cytogenetic stocks may help locate and isolate genes for useful agronomic traits.