Effect of Plant Growth Regulators and explants on efficient in vitro Regeneration of Broccoli (Brassica oleracea L. var. italica)

Abstract

An efficient in vitro regeneration protocol is a crucial tool in rapid production of desirable and essentially genetically identical plants and genetic engineering of the crop for improved characteristics. To establish a highly efficient, reliable and stable regeneration protocol for Broccoli (Brassica oleracea L. var. italica) several vital factors, like optimum concentration of appropriate growth regulators and explants, are very essential to be standardized. For this, hypocotyl and apical meristems were used as explants and cultured in MS medium incorporated with different hormonal combinations for callus induction (0.5, 1.0, 1.5, 2.0 mg/L NAA with 1.0 mg/L 2,4-D), shoot regeneration (1.5, 2.5, 3.5, 4.5 mg/L BAP with 0.5 mg/L NAA) and root initiation (0.20, 0.30, 0.5, 1.0 mg/L IBA). Among these concentrations, MS medium with 1.0 mg/L 2,4-D and 1.0 mg/L NAA was found best for callus initiation (72.5%) with average callus size of 7.32 cm2 and average callus weight of 3.52 g within 15 days from apical meristem. The MS medium with 3.5 mg/L BAP and 0.5 mg/L NAA showed the best shoot regeneration (62.5%), average no. of shoots (6.03) with mean shoot length (4.90 cm) within 45 days. The regenerated shoots were rooted well in MS medium containing IBA (0.20 mg/L) with highest root initiation (90%), average no. of roots (6.28) and mean root length (4.63 cm) within 15 days. The survival rate of well rooted plantlets in the soil was 90%. Thus, it can be concluded that apical meristem was the best explant for efficient in vitro regeneration of Broccoli in the above mentioned hormonal combinations and concentrations.