Cultivar identification and pedigree assessment of common wheat based on RAPD analysis
Wenguang Cao1*, P. Hucl2 , G. Scoles2, R. N. Chibbar3, P. N. Fox4 and B. Skovmand4
1Eastern Cereal and Oilseed Research Center, Agriculture
and Agri-Food Canada, Building 50,930 Carling Ave. Ottawa, ON K1A 0C6, Canada
2Dept. of Plant Sciences, University of Saskatchewan, 51 Campus Drive,
Saskatoon, Sask., S7N 5A8, Canada
3Plant Biotechnology Institute, National Research Council, Saskatoon,
Sask., S7N 0W9, Canada
4CIMMYT, Apartado Postal 6-641, CP. 06000, Mexico, D.F., Mexico
Summary
Knowledge of cultivar genetic relationships helps breeders make decision on the cross-combination in breeding programs, and cultivar identification is important for protection of breeders' right. Twenty-nine common wheat cultivars (Triticum aestivum L. em Thell) were used to evaluate randomly amplified polymorphic DNA (RAPD) analysis in identifying common wheat cultivars and assessing their pedigree relationships. Thirty-one primers produced polymorphisms were used in this study, generating a total of 214 reproducible amplified DNA fragments. The number of the DNA fragments for each primer varied from 3 to 12 with an average of 6.9 bands per primer. The sizes of DNA fragments ranged from 280 bp to 2800 bp. Out of 214 amplified products, 54.7% were monomorphic, and 45.3% were polymorphic, averaging 3.1 polymorphisms per primer. The marker RC37700, specific to AC Domain, was found after evaluating 74 wheat cultivars. The RAPD data were analyzed using the unweighted pair-group method with arithmetical averages (UPGMA). A dendrogram based on Jaccard coefficients generally grouped cultivars with similar pedigrees closer together than those known to be unrelated. The results from this study suggest that RAPD analysis can be used for pedigree assessment in common wheat and identification of some wheat cultivars.Key words: RAPD markers, cultivar identification, pedigree assessment, Triticum aestivum
Introduction
The identification of crop cultivars or breeding lines is important to protect breeder's right. Phenological and morphological characteristics may not be able to distinguish cultivars unequivocally (Mailer et al. 1994). Protein and isozyme electrophoresis has facilitated the identification of cultivars. However, the level of polymorphism often is insufficient to distinguish cultivars, and isozyme markers can be dependent on growth conditions and developmental stage (Kuhns and Fretz 1978; Falkenhagen 1985). DNA-based markers have largely overcome these disadvantages and have been applied successfully to discriminate among genotypes in a wide range of agricultural crops (Weising et al. 1991; He et al. 1992; Nybon 1994; Jain et al. 1994). Restriction fragment length polymorphism (RFLP) is a powerful technique and has been used to generate genetic maps in crop species such as tomato (Lycopersicon esculentum L.), potato (Solanum tuberosum L.), maize (Zea mays L.) (Helentjaris et al. 1986; Tanksley et al. 1989); barley (Hordeum vulgare L.) (Tragoonrung et al. 1992; Patrick et al. 1996); and wheat (Triticum aestivum L. em Thell) (Chao et al. 1989; Gill et al. 1991). The random amplified polymorphic DNA (RAPD) technique, however, is preferred to the RFLP technique because it is relatively easy, requires very little DNA and does not require radioactive probes (Marshall et al. 1994). The use of RAPD in distinguishing cultivars has been demonstrated in broccoli and cauliflower (Brassica oleracea L.) (Hu and Quiros 1991; Kresovich et al. 1992); celery (Apium graveolens L.) (Yang and Quiros 1993 ). The RAPD technique has also been used for taxonomic studies of the genus Pellia (Pacak et al. 1998), for parentage determination in hybrid rice (Oryza sativa L.) (Wang et al. 1994), for cultivar pedigree relationships in barley (Hordeum vulgare) (Tinker et al. 1993) and for cultivar identification in rye (Secale cereale L.) (Iqbal and Rayburn 1995).