Linamarin content and genetic stability of cassava plants derived by somatic embryogenesis

A protocol was established for high frequency cyclic somatic embryogenesis for different varieties of cassava. An efficient plant regeneration system was developed for the high cyanogenic variety PRC 60a. Linamarin content an d linamarase activity were determined in various tissues of secondary somat ic embryos and regenerated plants of PRC 60a. Both linamarin and linamarase activity were not detected in embryogenic callus, roots induced from callu s and somatic embryo tissues. The stems and leaves of regenerated plants (i n vitro) and storage roots and leaves of mature plants (in vivo), however, contained variable amounts of linamarin and linamarase activity whereas in the nonstorage root tissues (in vitro) only linamarin was detected. The pre sent study suggested that the linamarin biosynthetic pathway may be absent or not switched on in the embryogenic callus and somatic embryos. The ploid y level and somatic chromosome number of the regenerated plants were found to be same as the source plants. The availability of this regeneration syst em would be useful not only for investigating cyanogenesis but also for gen etic manipulation in cassava.