Morphogenic Response of Leaf and Petiole Explants of Broccoli Using Thidiazuron

Abstract

Broccoli (Brassica oleracea var. italica) is an important nutritionally rich vegetable cole crop grown in the world. 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 present study was to evaluate the potency of thidiazuron (TDZ) as a plant growth regulator in evoking morphogenic responses in leaf and petiole explants of broccoli. An efficient, reproducible, and high frequency plant regeneration protocol has been standardized in broccoli cv. Solan green head. Leaf and petiole explants were cultured on Murashige-Skoog (MS) medium, supplemented with a wide range of TDZ concentrations. The following treatments were designed for efficient in vitro shoot regeneration: 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 highest percentage of leaf explants producing shoot (89.25%) was recorded on MS medium containing 1.0 μM TDZ and 0.107 μM NAA. The multiple shoot regeneration response of petiole explant producing shoots (91.55%) was obtained on MS medium containing 2.0 μM TDZ and 0.107 μM NAA. Shoot multiplication and elongation were obtained on the same medium. For root regeneration in in vitro regenerated shoots, different concentrations of NAA were applied. High frequency (100%) root regeneration response with healthy and vigorous roots was observed on MS medium supplemented with 0.54 μM NAA. The regenerated plantlets with well-developed shoots and root system were transferred to pots containing cocopeat and successfully acclimatized. We recommend 1.0 μM TDZ with 0.107 μM NAA and 2.0 μM TDZ and 0.107 μM NAA combinations for adventitious shoot regeneration from leaf and petiole explants in broccoli cv. Solan green head respectively. This is the first report on high frequency organogenesis from leaf and petiole explants of broccoli cv. Solan green head using thidiazuron.