Abstract
The P genome of Agropyron cristatum Gaertn. contains many desirable genes that can be utilized as genetic resources to improve wheat. In this research, we used both the gametocidal chromosome 2Cc and the pairing homologous gene (Ph1b) mutant to induce structural aberrations and translocations between wheat and the 4P, 5P, and 6P genome chromosomes. By using the two approaches, a total of 19 wheat-A. cristatum translocations have been identified, in which 13 were induced by the Triticum aestivum cv. Chinese Spring (CS) ph1b mutant (CS ph1b) and six were induced by gametocidal chromosome 2Cc from Aegilops cylindrica Host. The wheat-4P, -5P and -6P A. cristatum translocations were characterized by in situ hybridization and by a set of conserved orthologous set (COS) molecular markers. The aberrations included centromeric translocations, terminal translocations, dicentric translocations, and deletions. The average induction frequency of chromosome structural aberrations was 10.9% using gametocidal 2Cc chromosome and 8.8% using ph1b mutant. The highest frequency obtained was for chromosome 4P using both approaches. All the wheat-A. cristatum translocation lines obtained were valuable for identifying A. cristatum chromosome 4P, 5P, and 6P related genes. In addition, these lines provided genetic resources and new germplasm accessions for the genetic improvement of wheat.
Highlights
A total of 86, 90, and 217 F2 plants were established from the crosses between the Chinese Spring (CS)/A. cristatum disomic addition line for chromosomes 4P, 5P, and 6P, respectively and the CS/Ae. cylindrica disomic addition line for the 2Cc gametocidal chromosome (Table 1)
The number of F2 plants containing P genome introgressions varied in the offspring of the three different crosses, namely, 21 (24.4%), 32 (35.6%), and 66 (30.4%) F2 plants were found with chromosome 4P, 5P, and 6P, respectively (Table 1)
A total of 13 (10.9%) plants contained wheat-A. cristatum translocations: four involving chromosome 4P (19.0%), four involving chromosome 5P (12.5%), and five (7.6%) involving chromosome 6P (Table 2). Most of these wheat-A. cristatum rearrangements were whole-arm translocations involving A genome chromosomes from wheat, as demonstrated by the absence of both pAs1 and GAA hybridization signals on wheat chromosome arms involved in the translocations (Figure 3b,d,e,l,m)
Summary
To enhance recombination between donor chromosomes and the wheat genome to produce wheat-alien chromosome translocations, different strategies were designed, such as ionizing irradiation, induction by Ph1 mutant, and gametocidal chromosomes. [33], Leymus racemosus (Lam.) Tzvelev [34]), and H. chilense [35,36,37] chromosomes added to common wheat Both ionizing irradiation and gametocidal chromosome 2C methods have been previously used to produce wheat-A. cristatum translocations [2,15,16,38,39,40]. In this work we present the development and characterization of structural rearrangements between wheat and chromosomes 4P, 5P, and 6P from A.cristatum using both the action of gametocidal 2Cc genes and ph1b deletion
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