Effect of synthetic auxins on callus induction from tea stem tissue

A study was initiated to establish an in vitro culture protocol for tea (Camellia sinensis). Explant sources, disinfestation methods and culture media were examined. Segments (divots) were dissected from greenwood stem (current year growth) internodes of field grown plants. Disinfestation was achieved by separate treatments of 3.75% sodium hypochlorite and 7.5% CaCl₂. MS medium with sucrose (30 g/L), inositol (100 mg/L) and thiamine-HCl (1.3 mg/L) and kinetin was used with combinations of the auxins: (2,4-dichlorophenoxy) acetic acid (2,4-D), (2,4,5-trichlorophenoxy) acetic acid (2,4,5-T), (naphthalene) acetic acid (NAA) and 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (Picloram). Picloram (10^-7M) induced the most callus proliferation without kinetin. At a constant level of kinetin (10^-5M), the concentrations inducing the most callus growth were 10^-7M for 2,4-D, 10^-6M for 2,4,5-T, 10^-7M for Picloram and 10^-8M for NAA. A factorial test of 2,4,5-T and kinetin concentrations showed the optimum for callus growth was 10^-7M and 10^-5M, respectively.Technical Contribution No. 2532 of the South Carolina Agricultural Experiment Station, Clemson University.Graduate Research Assistant and Professor, respectively.