Multiple shoot induction and plant regeneration in litchi (Litchi chinensis Sonn.)

Multiple shoot induction in Litchi chinensis Sonn. (litchi) has been achieved by two methods: (1) direct germination of litchi seeds in 6-benzylaminopurine (20 mg l-1)-supplemented MS liquid medium and supported on a filter-paper bridge and (2) in planta treatment with 6-benzylaminopurine (100 microgram on alternate days) of the axillary bud regions of plants germinated and maintained under sterile conditions. While the former method resulted in as many as 27.5 +/- 8.6 shoot buds from the cotyledonary node within 4 weeks, the latter yielded on average approximately 8 shoot buds from each treated node in 8 weeks. The cytokinin treatment in planta consisted of placing sterile filter paper moistened with sterile distilled water over the node and adding different concentrations of 6-benzylaminopurine. Both methods of multiple shoot induction were found to be effective for the five genotypes of litchi that were tested. The shoots elongated and rooted directly in vermiculite after a pulse treatment with IBA (25 mg/ml) for 15 min. Fungus growth which is a serious problem in litchi tissue culture, was controlled using a fungicide, Bavistin, and by eliminating organic nutrients from the growth medium.