Abstract
Agropyron cristatum (L.) Gaertn. (2n = 4x = 28, PPPP) not only is cultivated as pasture fodder but also could provide many desirable genes for wheat improvement. It is critical to obtain common wheat–A. cristatum alien disomic addition lines to locate the desired genes on the P genome chromosomes. Comparative analysis of the homoeologous relationships between the P genome chromosome and wheat genome chromosomes is a key step in transferring different desirable genes into common wheat and producing the desired alien translocation line while compensating for the loss of wheat chromatin. In this study, six common wheat–A. cristatum disomic addition lines were produced and analyzed by phenotypic examination, genomic in situ hybridization (GISH), SSR markers from the ABD genomes and STS markers from the P genome. Comparative maps, six in total, were generated and demonstrated that all six addition lines belonged to homoeologous group 6. However, chromosome 6P had undergone obvious rearrangements in different addition lines compared with the wheat chromosome, indicating that to obtain a genetic compensating alien translocation line, one should recombine alien chromosomal regions with homoeologous wheat chromosomes. Indeed, these addition lines were classified into four types based on the comparative mapping: 6PI, 6PII, 6PIII, and 6PIV. The different types of chromosome 6P possessed different desirable genes. For example, the 6PI type, containing three addition lines, carried genes conferring high numbers of kernels per spike and resistance to powdery mildew, important traits for wheat improvement. These results may prove valuable for promoting the development of conventional chromosome engineering techniques toward molecular chromosome engineering.
Highlights
Transferring desirable genes from wild relatives into common wheat is an important strategy for wheat breeding
In contrast to conventional disomic addition lines, this study identified 4 types of wheat–A. cristatum 6P disomic addition lines based on the alien chromosome (6P) rearrangements
The number of a complete set of wheat–A. cristatum disomic addition lines should be seven, with one pair of alien chromosomes corresponding to one disomic addition line, and there should be PLOS ONE | www.plosone.org
Summary
Transferring desirable genes from wild relatives into common wheat is an important strategy for wheat breeding. Since the 1950s, many wheat–alien chromosome disomic addition lines have been produced, such as rye [7], barley [8], Dasypyrum villosum [9], and several species of the genera Agropyron [25,26], Aegilops [10], and Thinopyrum [11]. These addition lines are often used as bridge materials to transfer desirable genes to wheat. Molecular markers have been widely used to determine the homoeologous relationships between alien and wheat chromosomes [27,62,63,64,65]
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