低压低氧条件下莴苣细胞超微结构及基因特性研究

Ultrastructure and Genetic Traits of Lettuce Cells under Hypobaric and Hypoxic Conditions

目的研究低大气压力下莴苣变种四季油麦菜植株在细胞、亚细胞和分子水平上的结构、组成和数量变化特性。方法在4种不同总压(101,10,20和30 kPa)条件下培养油麦菜植株,生长40 d后进行根尖细胞骨架免疫荧光定位观察,叶片电镜切片超微结构观察和rbcL基因序列分析。结果随着总压和氧分压降低,细胞数目减少、体积增大、核体积变小;叶绿体基粒发生断裂和堆积,体积变大,总数减少,片层模糊,以致发生解体;叶绿体体积变小并聚集,线粒体向叶绿体靠拢;微管的数量减少,长度缩短,且聚集在细胞核附近;叶片总DNA的序列比对未发现rbcL基因发生突变。结论低压低氧条件显著影响油麦菜植物细胞数量和结构,叶绿体超微结构以及微管的数量和形态,但rbcL基因并未发生突变。

Objective To investigate the changes of structures,compositions and quantity of lettuce at cellular,sub-cellular and molecular levels under the hypobaric and hypoxic conditions.Methods Lettuce（Lactuca sativa L var.＂Sijiyoumaicai＂） plants were cultivated under normal and hypobaric conditions（101,10,20 and 30 kPa） for 40 d respectively.Cytoskeleton immunofluorescence position,electron microscopic slice and rbcL gene sequence analysis were conducted after harvest.Results As in hypoxic environment the number and volume of lettuce cells decreased,the nuclear size became smaller;the chloroplast grana lamellae fractured and aggregated,causing the chloroplasts fewer and enlarged.Their lamellae became reduced and vaguer,which caused disintegration;the chloroplasts got smaller and aggregated,mitochondria got close to the chloroplasts;the number of microtubules decreased,length shortened and gathered in the vicinity of the nucleus;the analysis on total leaf DNA-sequence alignment showed no rbcL gene mutations under these extreme conditions.Conclusion Hypobaric and hypoxic conditions can affect the number and volume of lettuce cells,the chloroplast ultrastructure and the number of microtubules significantly,but rbcL gene mutation is not observed.