Search

Tomato buds of cv. Idkawy were cultured in vitro on solid MS medium with 0.2 mg-l BAP. The plantlets that were produced were exposed to different doses of gamma radiation, ranging from 100 to 200 Gy. Afterward, single pieces of nodes were cut and moved to a fresh MS medium with 0.2 mg-l of BAP. The gamma radiation caused a mortality rate of 18.75% to 52.5% among the explants. The surviving plantlets were then cut into single node pieces and transferred to an MS medium containing 0.2 mg-l of BAP, with added NaCl concentrations of either 50 or 100 mM. There was increased mortality of the vegetative buds on the explants with increased salt concentrations. It was shown that the all gamma radiation doses caused reduced the percentage of survival at saline levels. The genetic diversity was assessment by using ten primers for each SCoT and ISSR markers to six irradiated treatments grew under salt stress (100 Gy x 50 mM, 150 Gy x 50 mM, 200 Gy x 50 mM, 100 Gy x 100 mM, 150 Gy x 100 mM, 200 Gy x 100 mM). It was showed that the polymorphism percentage mean of SCoT marker (29.56%) is higher than the ISSR marker (26.78%). The average of PIC values for both markers SCoT and ISSR were 0.197 and 0.288 (PIC ˂0.5), as well as, MI values were 0.077 and 0.081, respectively. In contrast, when considering the number of alleles (Ne), Nei's genetic diversity (H), and Shannon's information index (I) parameters, it was observed that the greatest genetic variation was caused by the combined treatment of 200 Gy x 50 mM NaCl using the SCoT marker. On the other hand, with the ISSR marker, the highest induced genetic variation was seen with the combined treatment of 150 Gy x 50 mM NaCl. The obtained results demonstrate that SCoT marker was more accurate and efficient than ISSR marker for distinguishing and genetic variation analysis of irradiated tomato plantlets grew under salt stress. The relationships within treatments were estimated through cluster analysis (UPGMA) based on SCoT and ISSR analysis.

Haploid plants of Nicotiana alata were cultured in vitro on MS medium with IAA + KIN. The resulting plantlets were irradiated using gamma radiation doses of 10, 15, 20 and 25 Gy. Single node pieces were cut and transferred onto fresh MS medium. Gamma radiation doses caused the death of 9% and up to 28% of explants. NaCl concentrations caused the death of 8% up to 36% of explants, while the combined effect between gamma radiation doses and salinity had an impact suffused on the percentage of survival. The combined effect of gamma radiation doses 20 Gy and 25 Gy on NaCl concentrations of 100, 150 and 200 mM were deadly. Even more, the combined effect of gamma radiation doses and salinity had a severe negative impact on both the proline content and total soluble protein. Random amplified polymorphic DNA (RAPD) analysis was used to determine the degree of genetic variation in treated haploid Nicotiana alata plants. Total genomic DNAs from different haploid plantlets treated were amplified using five arbitrary primers. Two hundred and seventy bands were detected from plantlets irradiated with doses of 15, 20 and 25 Gy, with polymorphic band number 226 (83.7%). The total number of bands resulted from plant grew on 150 mM and 200 mM NaCl were 260 bands with polymorphic bands 185 (85.6%). However, the total number of bands produced from combined effects between gamma rays and salinity (20 Gy X 50 mM NaCl, 20 Gy X 100 mM NaCl and 25 Gy X 50 mM NaCl) were 270, with polymorphic band number 231 (85.5%). High similarity between treatments was revealed. Treatments relationships were estimated through cluster analysis (UPGMA) based on RAPD data.

Nicotiana alata anthers cultured on different modified media based on MS, MT and N were used to obtain haploid plants through direct and indirect ways. The haploid plants resulting on MS medium ranged from 52% - 80%, on MT medium ranged from 32% - 52% and on N medium ranged from 28% - 44%. Accordingly, the best medium used for haploid induction was MS supplemented with 0.2 mgl-l NAA + 0.5 mgl-l KIN. On the other hand, MS medium supplemented with 0.4 mgl-l NAA + 0.5 mgl-l KIN or 1.0 mgl-l BAP + 0.5 mgl-l NAA were the best mediums for callus induction and plant regeneration, respectively. Morphologically, the leaf size, stem highest and diameter, flower size and diameter, anther length and number were about 67% of the diploid plants growth. Irradiated anthers with doses of 0, 2.5, 5, 7.5, 10, 15, 20 and 25 Gy caused reducing the number of haploid plants with increasing gamma radiation dose. For the haploid plants irradiated with same doses, the mortality percentage of bud survival was increasing with increasing gamma radiation dose. The irradiated callus with doses of 0, 5, 10, 15 and 20 Gy was affected negatively on growth rate and morphology. Proline content in irradiated plantlets increased with increasing gamma radiation dose. As well, total soluble protein content was increased with gamma irradiation up to 10 Gy. However, the higher doses caused a severe decrease of total soluble proteins. The production of proline and total soluble proteins in haploid plants were 48.6% and 69.5%, respectively comparing with diploid plants.