Micropropagation in banana using high levels of cytokinins does not involve any genetic changes as revealed by RAPD and ISSR markers

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–1BA(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.