Effect of potent cytokinin thidiazuron on in vitro morphogenic potential of broccoli (Brassica oleracea L. var. italica), an important vegetable crop

Broccoli (Brassica oleracea var. italica) is an important nutritionally rich vegetable cole crop. Environmental stress, pests and diseases cause enormous yield losses because of a limited gene pool. Genetic manipulation is becoming an important method for broccoli improvement. The objective of the present study was to evaluate the potency of thidiazuron (TDZ) as a plant growth regulator in evoking morphogenic responses in hypocotyl and cotyledon explants of broccoli. Hypocotyl and cotyledon explants were used from 10 to 12 days old in vitro grown seedlings of broccoli and cultured on MS medium supplemented with wide range of TDZ concentrations for efficient in vitro shoot regeneration, viz., TDZ alone, TDZ with adenine, TDZ with naphthalene acetic acid (NAA) and TDZ with indole acetic acid (IAA). Among the 36 combinations of growth regulators used, the maximum percentage of shoot regeneration was observed in the hypocotyl explants (95.92 %) on MS medium supplemented with 2.0 µM TDZ and 0.5 µM IAA. The multiple shoot regeneration response of cotyledon explants producing shoot (88.88 %) were observed on MS medium supplemented with 2.0 µM TDZ and 0.59 mM adenine. Shoot multiplication and elongation were observed on the same medium. High frequency (93.99 %) of root regeneration was observed in in vitro regenerated shoots on MS medium supplemented with 1.08 µM NAA. The regenerated plantlets with well-developed shoots and root system were transferred to the pots containing a mixture of sand and soil and acclimatized. We recommend 2.0 µM TDZ and 0.5 µM IAA, and 2.0 µM TDZ and 0.59 mM adenine combinations for adventitious shoot regeneration from hypocotyl and cotyledon explants in broccoli cv. Solan green head respectively. This is the first report on high frequency organogenesis in broccoli cv. Solan green head using TDZ from India. © 2015, Indian Society for Plant Physiology.