In vitro culture methods in sorghum with shoot tip as the explant material.

Twenty-four diverse genotypes of sorghum were evaluated for response to callus induction and plant regeneration with two media viz., MS and NBKNB using shoot tips as the start material to identify a model genotype. None of the genotypes tested showed promising results. Therefore, alternative methods of in vitro pathways using shoot meristem isolated from shoot tips were explored. Shoot apical meristems were isolated and were induced to multiple shoots or multiple shoot buds pathway by manipulation of thidiazuron (TDZ), 6-benzyl adenine (BAP) and 2, 4-dichlorophenoxy acetic acid (2, 4-D). Choice of the pathway whether large-scale multiplication of shoots or production of target tissues for transformation can be exercised based on the needs and applications. A simple procedure, for large scale handling of shoot tips is described in detail. Electron microscopic studies revealed that meristems isolated from 7-day-old seedlings are superior because of possessing greater number of transformation competent cells.