Studies on some mutation induced through in-vitro propagation of banana plants in relation to resistance of some viruses diseases.

This work explores the possibility of using in-vitro technique to induce mutation of banana explants (Musa acuminate cv. Grand-Nain Cavendish subgroup, AAA) by physical, chemical mutation and increasing number of subcultures. By these mutations, we are trying to produce virus resistance in various susceptible banana crop and improving its yield and quality. The banana explants obtained by in vitro culture were subjected to gamma irradiation from 60CO sources at dose of20, 40 and 60 Gy; chemical mutation through culture the explants of the meristem on MS-medium supplemented with different concentrations of 2, 4-D (2, 4 and 6 mg/l) 6 Benzylaminopurine (6,7 and 8 mg/l), and Sodium azide (1, 2 and 3 mg/l). Also number of subcultures have been increased to 7th ,9th and 11 th for induction of mutation. Resulted explants obtained from different mutation methods were multiplied, elongated, rooted, hardened and acclimatized in the glasshouse and were shifted to the field. Changes in DNA caused by mutagens were detected by ISSR-PCR analysis using five random primers. Three primers (UBC-814, UBC-817 and UBC-835) produced polymorphism between the controls and banana plants treated with the physical mutagens, chemical mutagens and increased number of subculture. Regarding physical mutagen, the three primers (UBC-814, UBC-817 and UBC-835) showed 68.18 % mean W'lymorphism. Among the 15 polymorphic bands, four bands were specific markers with a total average of 18.18 %. However, the chemical mutagen primers (TJBC-814, UBC-817 and UBC-835) showed 82.86% mean polymorphism. Among the 29 polymorphic bands, 13 bands were specific markers with a total average of 37.14 %. Whereas, the increasing number of subcultures with the same primers (UBC-814, UBC-817 and UBC-835\} showed 63.16 % mean polymorphism. On the other hand, we did not find any markers in increasing number of subcultures. Field screening was carried out to two different isolates of BBTV and BMV by using syringe method of inoculation. There were only two treatments produced resistance to BMV (60 Gy irradiation dose and 6 mg/l of 2, 4-D). Among the treated plants, only three plants treated with 60 Gy irradiation dose and two plants treated with 6 mgil of 2, 4-D survived and inoculated and found to be resistant to BMV. At the same time, there was no BBTV -resistant banana plants. . Three mg/l Sodium azid gave the best results in open field regarding plant height (best height was 197 cm), bunch weight (best weight was 19.67 kg) and period in days from planting to harvest (least period was 385.30 days).