Institute for Molecular Biology and Biotechnology, Laboratorium voor Plantengenetica, Vrije Universiteit Brussel, B-1640, Sint-Genesius Rode, Belgium.
* Address for correspondence: Department of Plant Pathology, S.V. Agricultural College, Tirupathi 517 502, India.
The present study was carried to assess the genetic variability among lysine-rich cultivars (IS 21702, CVS 365, G 1058, G 205 and CVS 549) and compared with the low lysine cultivar White Martin and a chemically induced mutant P7210. The total kafirins from these cultivars were investigated by Sodium Dodecyl Sulphate-Poly Acrylamide Gel Electrophoresis (SDS-PAGE), isoelectric focusing (IEF) and reversed-phase high-performance liquid chromatography (RP-HPLC). The variation was also studied by leaf and seed esterase pattern. 50S-PAGE analysis of kafirins showed the absence of both 25.3 kD and 25.9 kD α-kafirin proteins in lysine-rich cultivars IS 21702, G 1058 and CVS 365 while only the 25.9 kD protein is not represented in G 205 when compared to white Martin and P7210. Isoelectric focusing profiles of kafirins indicated that the kafirin fraction is heterogeneous mixture consists of at least 10–15 polypeptides with a slight difference in their isoelectric point among the cultivars. RP-HPLC yielded significantly different elution profiles indicating qualitative and quantitative differences at the polypeptide composition, showing the genetic variability among these cultivars. Isozyme evaluations indicated more variability for the leaf and seed esterases, which could be used as a biochemical markers in breeding programs.
Sorghum bicolor, kafirins, esterase isozyme, SDS-PAGE, IEF, RP-HPLC
