Evidence of homoeologous introgression of the first and fourth groups of chromosomes of Aegilops umbellulata Zhuk. into wheat (Triticum aestivum L.)
Ts. Stoilova
Institute of Genetics 'D. Kostoff, Bulgarian Academy
of Sciences, Sofia-1113, Bulgaria
Summary
Homoeology between the chromosomes of the first and fourth groups in ten wheat lines derived from the population of F4 BC1 obtained after crossing between T. aestivum cv. Aurora and the wild species Aegilops umbellulata was investigated by analyzing the electrophoretic patterns of the gliadins, glutenins and albumins. Five lines expressed qualitative differences in two gliadin subunits GliB1 and GliA1 belonging to the omega- and gamma- gliadins respectively and quantitative differences in the albumin subunits compared to cv. Aurora. The other five lines were indistinguishable from cv. Aurora based on the gliadins. The possession of Ae. umbellulata- type subunit composition of the gliadins and glutenins controlled by the chromosomes 1BS (locus GliB1), 1AS+1DS (locus GliA1) and 1AS (locus GluB3) and the quantitative differences in the albumin subunits controlled by the chromosomes 4DL and 4BL provide evidence of homoeologous introgression from the U genome of Ae. umbellulata into cv. Aurora.
Key words: wheat, Aegilops umbellulata, seed storage
proteins, homoeologous relationships
introduction
Besides cytological parameters (Maestra and Naranjo 1997), biochemical markers provide an effective means for determining the homoeologous relationships of alien chromosomes from the related species and chromosomes of hexaploid wheat. Protein and isoenzyme markers have been established for all homoeologous groups of chromosomes in tribe Triticeae (McIntosh 1988) and successfully used for determining the homoeology of the added or substituted alien chromosomes. William and Mujeeb-Kazi (1995, 1996) identified a high molecular weight (HMW) glutenin and beta-amylase markers for the presence of Thinopyrum bessarabicum and Aegilops variabilis chromosomes in amphiploids and disomic addition wheat lines. As the genes for MW glutenins and beta-amylase isoenzymes are respectively located on the long arms of homoeologous group 1 chromosomes (Lawrence and Shepherd 1981) and 4A, 5A and 4D chromosomes (Ainsworth et al. 1983) in wheat, the observed markers could serve as evidence for determining chromosome homoeology between the two alien species with wheat. Similarly, by analyzing beta-amylase isoenzymes identification of alien chromosome and determination of chromosome homoeology of wheat were made in T.aestivum-Aegilops markgrafii amphiploid and addition lines of wheat (Schmidt et al. 1993). The study of the homoeology of the chromosomes by analyzing the protein patterns of interspecific hybrids thus provides effective approach as it enable to reveal the relationships between most of the wheat and alien chromosomes.
Aegilops umbellulata Zhuk. (syn. Triticum umbellulatum, 2n=14, UU) is a potential donor of a complex of genes for disease resistance (Sears 1954, 1956), early maturity and high grain protein content (Bochev 1988). With the objective of transferring genes of Ae. umbellulata chromosomes and establishing homoeology with the wheat chromosomes, a set of F4 BC1 lines have been selected from crosses between bread wheat cultivar Aurora and Ae. umbellulata (Ganeva et al. 2000). They were used to study the homoeologous relationships between the first and fourth chromosome groups of wheat and Ae. umbellulata by comparing endosperm protein markers.