Homoeoallelic gene Ncc-tmp of Triticum timopheevii conferring compatibility with the cytoplasm of Aegilops squarrosa in the tetraploid wheat nuclear background.
A nuclear gene, Ncc-tmp1A, of Triticum timopheevii is required for the nucleus-cytoplasm (NC) compatibility in tetraploid NC hybrids with the cytoplasm of Aegilops squarrosa. A euploid NC hybrid of T. durum was previously produced by introgressing the gene from chromosome 1A of T. timopheevii. To examine the possible presence of a functional homoeoallele in the G genome of T. timopheevii, segregation of seed viability was studied as a marker phenotype in BC1s involving the two types of NC hybrids, (Ae. squarrosa)-T. timopheevii and (Ae. squarrosa)-T. turgidum. The result of these test crosses suggested that the G genome possesses a functional homoeoallele Ncc-tmp1G. Segregation of two RAPD (random amplified polymorphic DNA) markers that were closely linked to Ncc-tmp1A was further studied among the viable BC1s obtained from a test cross of (Ae. squarrosa)-T. timopheevii x T. turgidum. Some viable BC1 segregants without the markers were obtained, suggesting a limited degree of transmission of chromosome 1G carrying Ncc-tmp1G. However, a similar RAPD analysis of BC1s obtained after backcrosses of reciprocal F1s of T. timopheevii/T. turgidum with T. turgidum showed random marker segregation. Thus, it was concluded that Ncc-tmp1A is not required for compatibility with its own cytoplasm. Southern blot analysis of the euploid NC hybrid using RFLP (restriction fragment length polymorphism) markers on the homologous group 1 chromosomes showed that Ncc-tmp1A locates in the centromeric region.
Asakura
N
N
Laboratory of Biology, Faculty of Engineering, Kanagawa University, Yokohama, Japan. asakura@cc.kanagawa-u.ac.jp
Nakamura
C
C
Ohtsuka
I
I
D000483:Alleles; D002467:Cell Nucleus / Q000235:genetics*; D003433:Crosses, Genetic; D003593:Cytoplasm / Q000235:genetics*; D017343:Genes, Plant; D005838:Genotype; D008540:Meiosis; D011003:Ploidies; D006109:Poaceae / Q000235:genetics*; D019105:Random Amplified Polymorphic DNA Technique; D014908:Triticum / Q000235:genetics*