Tissue culture and somatic embryogenesis of Mikania micrantha H. B. K.
薇甘菊组织培养及体细胞胚胎发生的研究

Using MS as the basal culture medium,the effects of 4 kinds of explants and 10 different combinations of various phytohormone concentrations on callus formation and plantlet regeneration of Mikania micrantha H.B.K.were studied.A high frequency plantlet regeneration system was obtained and all the developmental stages of the somatic embryogenesis were examined by means of histocytological method.The results showed that all the explants and media used successfully induced both callus formation and plantlet regeneration,and the medium containing MS+6BA1 mg/L was testified to be much better than others for inducing callus,but the timing of the callus formation differed with different explants.MS medium containing MS + NAA 2 mg/L + KT 0.1 mg/L + 6BA 2 mg/L was found to be more preferable for inducing somatic embryoid from embryogenic callus for bud sprouting.However,callus redifferentiation occurred only in calli induced from young leaves and flower buds,while no callus redifferentiation were observed in shoot-tips as well as shoot segments with axillary buds.The somatic embryoid was found to originate from some single embryonic cell inside the callus tissue.The first division of the embryonic initial cell resulted in a two-cell proembryo(composed of an embryo cell and a suspensor cell),which ultimately developed into a mature embryoid with cotyledons through the intermediate stages of four-cell proembryo,eight-cell proembryo,sixteen-cell proembryo,multicelluar proembryo,globular embryo,heart-shaped embryo,torpedo-shaped embryo and,finally,cotyledonous embryo,which subsequently grew to form a plantlet.