A comparison of T_m selectivity studies of DNA/DNA duplex formation of C-5 thiopropyne-substituted thymidine containing oligodeoxynucleotides with unmodified oligodeoxynucleotides and C-5 propyne-substituted thymidine containing oligodeoxynucleotides is presented. Melting temperature (T_m) data reveal that duplex C containing thiopropyne oligodeoxynucleotide is stabilized at 2.6 °C more than the duplex A which contains unmodified oligodeoxynucleotide and T_m of the duplex F is 6 °C lower than that of duplex D which contains unmodified oligodeoxynucleotide. However, in both the duplexes C and F, increase in selectivity was observed.

In order to improve the crop productivity, ensure quality of germplasm and minimize infection in various crops, particularly in the ornamental plants such as cultivars of Gladiolus, proper diagnosis and quality control is essential (Bertaccini et al., 1992; and Katoch et al., 2003). To maintain the quality in exporting planting material, countries have imposed strict quarantine conditions. Although many diagnostic tools have been developed for the detection of viral diseases, the incidence of viral infection is increasing. The diagnosis of viral infection in different parts of the plants, particularly in propagating material, indirectly helps in controlling the infection. DNA/RNA probes, polymer chain reaction and other molecular biology techniques have been applied to detect infection (virus) in planting material. These techniques offer great specificity and selectivity. While importing or purchasing the GMO and/or GURT technology for crop production, the quality of the planting material is ensured by molecular biology techniques.

The DNA probe techniques are an important instrument for the development of rural society. The selectivity studies of oligodeoxynucleotides for preparing probes and primers are important for correct and reliable diagnostic. For diagnosis of viral diseases, the oligodeoxynucleotides should be optimally designed so that they can form stable hybrids with the target sequence and they should have the least possible nonspecific binding. To achieve the high specificity, few modifications have been reported in the hybridization protocols (Matthews and Kricka, 1988; Harel-Bellan et al., 1989; Bielinska et al., 1990; Wetmur, 1991; Tuerk and Gold, 1999; and Bock et al., 1992; ). However, for this purpose, modified oligodeoxynucleotides have not been studied in detail (Kool, 1991; Wagner et al., 1993; and Chaudhuri and Kool, 1995). Binding studies of the modified oligodeoxynucleotide with the respective target oligodeoxynucleotide would be helpful in the design of oligodeoxynucleotides with high selectivity.

Chemistry Journal, C-5 Thiopropyne-Substituted Thymidine, Oligodeoxynucleotide, DNA Duplex Formation, Molecular Biology Techniques, Hybridization Protocols, Thiopropyne Oligodeoxynucleotides, Viral Infection, Thermal Denaturation Studies, SpeedVac Concentrator.