Micropropagation in banana using high levels of cytokinins does not involve any genetic changes as revealed by RAPD and ISSR markers
2007
Venkatachalam, Lakshmanan | Sreedhar, R. V | Bhagyalakshmi, Neelwarne
Use of high levels of growth regulators during micropropagation results in undesirable clonal variability in important commercial crops such as banana. The present study investigated the effects of high levels of cytokinins on micropropagation in banana (genotype AAB), and the genetic stability of plantlets was assessed using RAPD and ISSR markers. Cytokinins, such as BA and kinetin were added to the routine shoot multiplication medium at concentrations up to 10 mg l-¹. After 12 weeks of culture involving three subcultures, the maximum number of shoot buds were produced in cultures receiving either 5 mg l-¹ BA (80 shoot buds) or 4 mg l-¹ kinetin (62 shoot buds). Certain morphological abnormalities observed during proliferation of shoot buds in vitro were not observed during acclimatization ex vitro. To check the genetic stability, RAPD and ISSR profiles of micropropagated plantlets obtained from different cytokinin-treatments were compared with control microplants maintained on MS medium as well as the field-grown mother plant. A total of 50 RAPD and 12 ISSR primers resulted in 625 distinct and reproducible bands. Thus a total of 17,400 bands were generated showing homogeneous RAPD and ISSR patterns. Band intensity histogram of each gel confirmed their monomorphic nature with no genetic variation in all the plantlets analysed. Based on these results a protocol for high rate shoot multiplication was worked out leading to uniform shoot production.
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