Slow-growth in vitro storage of plum (Prunus salicina Lindl.) shoot cultures

摘要

Slow growth storage of tissue culture collections of different crops is a standard method of germplasm conservation (Bhojwani and Razdan, 1). Storage by slow growth is only applicable to organized shoot cultures and the term 'slow growth' also covers'growth limitation' or 'growth inhibition', which imply modification of culture media and/or growth conditions to achieve slow growth of plant material in vitro. High labour input and expenditure in establishment are required for maintenance of tissue culture collections. To slow down the growth and extend intervals between sub-cultures, culture conditions can be modified (Engelman, 2; Harding, 3) usually with inclusion of mannitol in culture medium to reduce the water potential of medium so that tissuecultures are subjected to growth inhibiting osmotic stress. However, a combination of slow growth medium with reduced temperature (6° to 10°C) has given better results than either treatment applied alone (Ng and Ng, 9). In the present investigation, an attempt has been made for slow growth in vitro storage of two plum (Prunus salicina Lindl.) varieties, viz. Hybrid plum and Santarosa by addition of mannitol in culture medium and/or storage of shoot cultures at 6°C with a view to extend the intervalsbetween sub-culture. Clonal in vitro propagation of plum is routinely carried out at our laboratory on shoot proliferation medium, i.e. half-strength nitrate containing MS medium (Murashige and Skoog, 8) supplemented with NAA (1 mg l~(-1)) + BA (1 mg I~(-1)), 3% sucrose and 0.6% phytagars (Kumar and Kumar, 5).