组织培养中硝酸镧对大花蕙兰原球茎超微结构的影响

THE EFFECT OF LANTHANUM NITRATE ON THE PROTOCORM ULTRASTRUCTURE OF CYMBIDIUM HYBRIDUM TISSUE CULTURE

大花蕙兰（Ｃｙｍｂｉｄｉｕｍｈｙｂｒｉｄｕｍ）原球茎分别培养在３种不同成分的培养基上：Ⅰ组含有稀土硝酸镧和微量元素；Ⅱ组含有微量元素而无稀土元素；Ⅲ组含有稀土硝酸镧而无微量元素。１０ｄ后，取其幼原球茎制作超薄切片进行电镜观察，得知：含硝酸镧１５ｍｇ／Ｌ的条件下可促进幼原球茎组织中细胞的胞间连丝通道、内质网和细胞器等的发育，从而表明硝酸镧对外植体的增殖和分化有一定的促进作用。

The effect of lanthanum nitrate on preliferation and differentiation of outward plantbody were inquired into further on the basis of studying the effect of lanthanum nitrate on cell structure of protocorms.Protocorms of Cymbidium hybridum were cultured in the following three media.Group Ⅰ,MS supplemented with 0.5mg/L 2,4-D and 1 mg/L 6-BA and 15mg/L lanthanum nitrate.Group Ⅱ,MS supplemented with 0.5mg/L 2,4-D and 1 mg/L 6-BA Group Ⅲ,MS(excluding the trace element) supplemented with 0.5mg/L 2,4-D and 1 mg/L 6-BA and 15 mg/L lanthanum nitrate.After 10 days cultivation, little squares(1 mm×1 mm×0.5 mm)along the tops of the young protocorms were cut vertically,then fixed by glutaraldehyde and osmium tetroxide,embeded by Spurr resin, cut into sections with the thickness of 60nm,stained by uranium acetate and lead citrate.At last,observed under TEM and take photographs.Three groups of ultra thin sections enlarged 5000 to 60 000 times were observed under HITACHT-600 TEM,for primary wall,intercellular layer, plasmodesmata canal, plasmodesmata,plasma membrane,endoplasmic reticulum, mitochondrion, plastid,amyloplast,microbody,microtubule etc.Could all be seen in any mature cell of the sections,the nuclear envelope between the nucleus and cytoplasm was apparent and the nucleolus and chromatin existed in the nucleus.After comparing the three groups of the sections,we discovered that the plasmedesma canals,Plasmodesmata of the cells of the young protocorms in media including lanthanum nitrate were quite thick and colours were also dark, densities of the endoplasmic reticulum,mitochondrion,plastid,ribosome and the other materials concentrated electron in the group Ⅰ were higher than those of the group Ⅲ which were higher than or equal to those of the group Ⅱ.The conditions(Ⅰ≥Ⅱ> Ⅲ and Ⅰ>Ⅱ≥Ⅲ) were also observed, but rarely the effect of lanthanum nitrate on the structures of the young cells and mature cells were the same,sometimes,obviously more proplastids standing in cell division state in the sections of the group Ⅰ than those of the other groups could also be observed.