Choi YE et al., Plant Cell Reports 18: 493-499 (1999)
Summary
Abstract Coty1edon exp1ants of immature ginseng zyｭ
gotic embryos cu1tured on Murashige and Skoog medium
lacking growth regu1ators formed somatic embryos di ・
rect1y, most in a mu1tip1e state, fused together and to the
parent coty1edon exp1ants. When the coty1edon explants of
ginseng were pretreated with 1.0 M sucrose for 24-72 h,
al the somatic embryos developed individually from all
surfaces of the cotyledons and the number of somatic emｭ
bryos per explant was enhanced fourfold.Hi sto10gical obｭ
servation revealed that all the single somatic embryos from
preplasmolysed cotyledons originated from epidermal sirト
gle cells, whereas all the multip1e embryos from coty1eｭ
dons without pretreatment originated from epiderma1 and
subepidermal cell masses.W hen the somatic embryos ma・
tured to the cotyledonary stage, further growth ceased and
they remained white, probab1y indicating dormancy. Gibｭ
berellic acid (GA3) (over 1.0 mg/1) or chi11ing treatment
(-20C for over 8 weeks) were prerequisites for the germiｭ
nation of somatic embryos.U1 trastructural observation reｭ
vealed that the cotyledon cells of somatic embryos withｭ
out chilling or GA3 treatment contained numerous 1ipid reｭ
serves, dense cytop1asm, proplastids and non-activated miｭ
tochondria, whereas the cotyledon cells of somatic emｭ
bryos after chi11ing or GA3 treatment were highly vacuoｭ
lated and contained well-developed chloroplasts and acｭ
tive-state mitochondria enc10sing numerous cristae, indiｭ
cating that in-vitro-deve10ped somatic embryos of P.gi n- l 叩a句y be刊 dd…
tωo zygo飢ti比c embryos.