Improvement of Micropropagation through Combination of Plant Growth Regulators in Indonesian Sorghum Hybrid Cultivar

Abstract

Sorghum is a tropical grass used for various purposes including food, animal feed, and biofuels source, but its in vitro propagation still found an obstacle due to tissue browning. This study aims to propagate and regenerate callus in the Indonesian sorghum hybrid, named Numbu cultivar from seed and meristematic leaf whorl explants. The combined effect of plant growth regulators (PGRs), namely 2,4-D and proline as well as NAA (naphthalene acetic acid) and BAP (6-benzyl amino purine) was investigated on embryogenic callus induction and regeneration, respectively. The results showed that callus induction was significantly faster in the seed explants compared to leaf whorl. The optimal medium used to obtain a large induction in the seed explants was MS salt containing 3 mg L-1 2,4-D and 5000 mg L-1 proline, which gave a 68% yield. Furthermore, the best medium used to obtain a high plant regeneration frequency was the MS medium containing 0.1 mg L-1 NAA and 3 mg L-1 BAP, which regenerated 78% of the callus into plantlet. The addition of 560 mg L-1 proline to the combination medium increased doubled the regeneration into the planlet. Based on the results, PGRs combinations are required to improve embryogenic callus induction and regeneration into planlet in sorghum.