Control of Bacteria and Alteration of Plant Growth in Tissue Cultures of Tansy (Tanacetum vulgare L.) Treated with Antibiotics

Abstract

Ten bacteria were isolated from the in vitro shoot cultures of different tansy (Tanacetum vulgare) genotypes. All isolates were Gram-negative. Five isolates belonged to Enterobacteriaceae, three isolates were strains of fluorescent Pseudomonas, and two isolates were strains of other aerobic bacteria. The combined treatment with gentamicin (50 mg·L–1) and rifampicin (25 mg·L–1) prevented the growth of all bacteria, whereas none of the antibiotics (ampicillin, cefotaxime, rifampicin, gentamicin, or streptomycin) controlled all bacteria when used alone. The antibiotics ranged based on their increasing adverse effects on shoot cultures as follows: rifampicin, cefotaxime, and gentamicin. Increased antibiotic concentration reduced the initiation and growth rates of shoots, roots and calli with some exceptions. Low concentrations of gentamicin and cefotaxime both increased the growth rate and shoot number per plant. Rifampicin stimulated the root growth of some of the biotypes tested. The growth rate of calli increased significantly in the presence of both gentamicin (25 mg·L–1) and rifampicin (25 mg·L–1) in the growth media, whereas the use of either antibiotic alone reduced the calli growth relative to the control. Viability of tansy protoplasts was enhanced by rifampicin and to a lesser extend by gentamicin and cefotaxime. The growth of bacteria isolated from tansy tissue culture can be prevented with a combined gentamicin and rifampicin treatment. The growth rate of plants decreased slightly when grown in the media supplemented with the same antibiotic combination. However, the growth retardation was not permanent, and the plants recovered and grew vigorously when transferred to antibiotic free medium.