High Rate of Plant Regeneration from Cultured Protoplasts of two Medicinal Plants: Solanum laciniatum Ait. and Solanum khasianum C. B. Clarke

Abstract

Summary Solanum laciniatum and S. khasianum plants were propagated by subculturing leafy single node cuttings. The sources of protoplasts were lamina and stems for S. laciniatum, and only lamina for S. khasianum. They were taken from 4-week old plants. Lamina gave the best yield of protoplasts. The first division of protoplasts occurred after 3–5 days of culture in KM8p + 0.2 mg · l −1 2,4-D + 0.5 mg · l −1 zeatin + 1 mg · l −1 NAA. At day 7, the division frequency was estimated at 39.0 % and 26.7 % for lamina and stem protoplasts of S. laciniatum, respectively, and 23.0 % for S. khasianum. After 20–30 days, a dilution of the cultures to 5 times with zeatin or kinetin-containing medium resulted in the formation of meristematic nodules in S. laciniatum with a frequency of 95 %, but only in an increase of callus growth in S. khasianum without any formation of organized structures, especially at a low level of cytokinin (0.1 mg · l −1). The nodules were composed of very small meristematic cells. They were partly covered with an epidermis and still connected with the callus. No bipolar structures were observed. The nodules produced only shoots on MS + 0.5 mg · l −1 BAP with a frequency of nearly 90 % and irrespective of protoplast sources. On MS + 2 mg · l −1 zeatin + 0.1 mg · l −1 IAA, more than 80 % of S khasianum calli regenerated buds which further developed into plantlets when transferred onto MS + 0.1 mg · l −1 BAR