Evidence for the origin of the B genome of bread wheat based on chloroplast DNA

Authors : Nadia HAIDER

Pages : 13-25

View : 23 | Download : 13

Publication Date : 2012-02-01

Article Type : Research Paper

Abstract :The hexaploid bread wheat Triticum aestivum L. insert ignore into journalissuearticles values(AABBDD); is thought to have originated through one or more rare hybridization events between Aegilops tauschii insert ignore into journalissuearticles values(DD); and the tetraploid Emmer wheat T. turgidum subsp. dicoccon insert ignore into journalissuearticles values(AABB);. The progenitor of the A genome of T. aestivum has generally been accepted to be T. urartu. The origin of the B genome, however, is controversial and still relatively unknown. Research has found the B genome in T. turgidum to be closely similar to the S genome in section Sitopsis of Aegilops L.; the Sitopsis diploid species were thus proposed as the probable maternal parent in the original cross that resulted in the tetraploid T. turgidum. Moreover, the donor of the cytoplasm of T. turgidum and T. aestivum was also the donor of most, if not all, of the B genome chromosomes. The present study attempts to investigate the polymorphism of chloroplast DNA between T. aestivum and 8 different Aegilops species using cleaved amplified polymorphic sequence insert ignore into journalissuearticles values(CAPS); and sequencing on 28 chloroplast loci in order to identify the chloroplast donor insert ignore into journalissuearticles values(B genome donor); of bread wheat. A phylogenetic tree based on the data generated demonstrates that Ae. speltoides was distinct from the other Aegilops species analyzed and the most closely related to bread wheat. It can be concluded that Ae. speltoides may be the chloroplast donor to bread wheat and the donor of its B genome. Understanding hexaploid wheat origin would further its genetic improvement and is also important for the artificial development of synthetic forms.
Keywords : Key words Aegilops, CAPS, chloroplast DNA, identification, sequencing