Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/1998
Publication Date: N/A
Interpretive Summary: Cytoplasmic male sterility could be used to produce hybrid durum wheat. But, it was discovered that some cytoplasms, such as that from Aegilops longissima, are not as compatible with the genome of durum wheat as they are with the genome of common hexaploid wheat. Compatibility of this cytoplasm with durum wheat can be improved by transfer of "species cytoplasmic specific" genes from common wheat to durum wheat. One of these genes is on chromosome 1D and the other is on chromosome 1A. We attempted to locate the gene on chromosome 1A by crossing with the aneuploid double ditelosomic 1A of durum wheat. No crossovers were recovered. Therefore, the gene is very close to the centromere on chromosome 1A. However, a translocation of the gene on 1D to a 1A chromosome was obtained.
Technical Abstract: A species cytoplasm specific (scs) gene derived from Triticum timopheevii on chromosome 1A(1A**scs) and the one on chromosome 1D from common wheat improve compatibility between durum wheat (T. turgidum L. var. durum) and Aegilops longissima S.&M. (lo) cytoplasm. The (lo) scs durum lines thus produced are male sterile and when crossed with durum produce viable plump seeds carrying scs and inviable shriveled seeds without scs. Objectives o the present study were to determine centromere-scs linkage distances, and viability and transmission of female gametes carrying one or both scs genes. The (lo) scs durum heterozygous for 1A/1A**scs was crossed with Langdon durum disomic substitution line 1D**scs(1A) where 1A chromosome pair is substituted by a 1D**scs pair. Two types of 1A+1D double monosomic F1s were recovered, (lo) durum 13"+1A**scs+1D**scs and (lo) durum 13"+1A+1D**scs, which were confirmed in progeny tests with normal durum. For centromere mapping, these lines were crossed with Langdon double ditelosomic 1A(2n=30; 13"+2t" (t"1AL+t"1AS)) and progeny examined for meiotic chromosome constitution. No telocentric 1AL**scs arising from recombination with 1A**scs was detected indicating that scs is tightly linked to the centromere on chromosome 1A. To determine the transmission of female gametes carrying one or both scs genes, (lo) durum 13"+1A**scs+1D**scs was crossed with LDN dbl-ditelo 1A and control durum. The functional female gametes carried one or both scs genes. Crosses of (lo) durum 13"+1A+1D**scs to LDN dbl-ditelo 1A produced several plants with a 1AL.1DL translocation chromosome. The formation of this chromosome was coupled with a strong selection for the scs gene on 1DL.