Production of virus free plants of African marigold (Tagetes erecta L.) through shoot meristem culture

Viral diseases are responsible for poor quality of flowers of marigold, one of the most remunerative flower crops, in terms of size, shape and discolouration and foliage injury including necrosis, mottling, mosaic etc. Biotechnological approaches like shoot meristem culture have been accepted to be an efficient therapeutic technique capable of eradicating viruses from infected plants. During present investigations, African marigold (Tagetes erecta L.) cv. Pusa Narangi Gainda was selected as an experimental material due to the presence of prominent symptoms and wide susceptibility. The infected piants were- indexed both serologically and biologically and were found to be infected with potato Y polyvirus (PVY). Virus cultures were maintained under in vitro conditions by culturing nodal segments from infected plants of African marigold. The most suitable medium for establishment and shoot multiplication was found to be MS medium supplemented with 2.5 mg/l IBA and 0.5 mg/l NAA. Different sizes of meristems ranging From 0.2 to 1.0 min were cultured on standardized MS medium supplemented with 0.1 mg/l NAA and 4.0 mg/l kinetin. Better size of meristem increases the survival rate also. PVY was not detectable in plants raised from meristems ranging between 0.2-0.4 mm. For root regeneration, half strength MS medium supplemented with 2.5 mg/l IBA and 0.2 per cent charcoal was found to be the best.