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Optimization of selected plant growth regulators on callus induction of Oryza
sativa L. var MR 219

MR 219, an indica rice from a cross between MR 137 and MR 151 is a long-grain rice
variety of high-yielding, good quality of shape and taste, short maturation as well as
resistance to blast and bacterial leaf blight. However, it is regarded as a recalcitrant variety
due to its low ratio of callogenesis and regeneration in in vitro culturing. This would be a
hindrance to crop improvements such as genetic transformation and other crop
improvement methods. The objective of this study was to optimize the concentrations and
combinations of plant growth regulators (PGRs) which were 2,4-Dichlorophenoxyacetic
acid (2,4-D), Kinetin (KIN) and Naphthalene acetic acid (NAA) on its callus induction
that ranging from 0.5 to 15.0 mg/L. The callus was induced from the mature seeds of MR
219 on the Murashige and Skoog (MS) media supplemented with 4.4 g/L of MS powder
with vitamins, 30.0 g/L of sucrose and 3.5 g/L of gelrite with the addition of 2,4-D, KIN
and NAA in different concentrations and combinations. All media supplemented with 2,4-
D had successfully induced the callus and 2.0 mg/L of 2,4-D was the best concentration
for the callus induction with a 100% success rate. The addition of 15.0 mg/L of NAA,
provided less time taken for callus induction with better callus morphology which resulted
in fewer browning problems.