草莓组织培养细胞发育过程的电镜观察

草莓的茎尖和茎节在添加适当浓度植物激素的MS培养基上诱导愈伤组织并分化出试管苗. 分别取不分化的愈伤组织、分化的愈伤组织及小苗的幼嫩叶片常规电镜观察.结果表明,不分化的愈伤组织细胞, 液泡较大,细胞质较稀薄,细胞内的各种细胞器不容易看到; 分化的愈伤组织的细胞,液泡较小,细胞核明显较大,核仁清晰可见,亦可以清楚地看到各种细胞器如叶绿体,线粒体,内质网,核糖体等以及淀粉粒; 已发育的幼嫩叶片细胞观察到有大量的叶绿体分布,其内部结构复杂,不仅基粒数多,基粒内囊体个数增加,而且基粒中片层密集,并可观察到大量的淀粉体.因此,草莓外植体的不同发育阶段的培养物在细胞超微结构水平上有显著的差异.这可以作为鉴别早期愈伤组织细胞分化能力的指标,并还可以作为选择适宜培养条件的依据

The Electron Microscopic Observation of the Tissue Culture Cell of Fragana ananassa Duchesne

Shoottips and stem nodes ofFragaria ananassa w ere excised and cultured on MSm edium w ith propergrow th regulators; callus wereinduced and plantletsw ere regener- ated. Sam ples from undifferentiated tissue and differentiated tissue as well as from young leaves ofthe plantlets w ere prepared for electron m icroscopic exam ination. There is a signifi- cantdifference am ong the three kindsoftissue observed underelectron m icroscope. In cells of differentiated tissue, the vacuoles w ere sm alland the nucleus occupied large partofthe cells, w ith a clear nucleus. The organelles such as chloroplasts, m itochondria, endoplasm ic reticu- lum and starch grain w ere clearly identified. In cells ofyoung leaves, large num ber ofchloro- plasts appeared. The chloroplastshow ed a com plex inner structure underelectron m icroscope: containing lot of granum s and thylakoids as w ellas clotty frets. A large quantity of starch grains w ere also observed. These results revealed thatduring the in vitro developm entofFra- garia ananass explant, the cultured cells displayed significant change in vltrastructure-struc- ture, w hich m ay be used in early identification ofdifferentiation potentialofthe callus orused to assistthe screening ofproperculture condition.