Study and characterization of the Ph1 locus as tool to promote interspecific chromosome associations between wheat and barley species

Abstract

Interspecific hybridization is used to introduce desirable characters from related species into allopolyploids such as wheat. The development of substitution and addition lines of related species in bread wheat can be useful as a genetic tool to transfer agronomic traits in the background of bread wheat. However, there is a low level of pairing and recombination between wheat chromosomes and those from the relative species. Different approaches have been carried out to promote pairing and recombination between related chromosomes such as the ph1b mutant, ionizing radiations and gametocidal genes. However, the most important discovery has been the Ph1 locus which regulates pairing and recombination between homologous chromosomes during meiosis in wheat. Thus, in its absence, related chromosomes could associate and recombine. Chapter 2 of this work examines the dynamic of DNA replication during premeiosis and early meiosis in wheat using flow cytometry, which has allowed the quantification of the amount of DNA in wheat anther in each stage meiotic stage. Chromosome replication was detected in wheat during premeiosis and early meiosis until the stage of pachytene, when chromosomes are associated in pairs to further recombine and correctly segregate in the gametes. Also, an important role of the Ph1 locus on the length of meiotic DNA replication in wheat was shown using flow cytometry. Chapter 3 deals with chromosome manipulation to induce meiotic recombination between barley and wheat in the absence of the Ph1 locus. Genetic crosses between the ph1b mutant and both wild and cultivated barley substitution and addition lines in wheat were carried out. More than...