【作者】 韩蕾；

【导师】 彭镇华； 孙振元；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2005， 博士

【摘要】 太空环境通过高真空、微重力、强辐射、高能粒子辐射、交变磁场及其它因素的单独或复合作用,影响植物的生长发育,诱发植物体不同水平的突变。这是扩大遗传变异,创造新种质和培育新品种的重要方法之一。本研究以草地早熟禾品种‘纳苏’（Poa pratensis L. ‘Nassau’）为试材,通过“神舟”三号飞船（SZ-3）（飞行时间为162hr,近地点为200km,远地点为343km,舱内温度为15～25℃,气压为10⁵Pa）进行搭载处理。未搭载种子为对照,经地面种植后研究了太空环境在个体水平、细胞水平、代谢水平以及分子水平等不同层次上的诱变效应,取得如下结果: 太空环境处理后,草地早熟禾种子发芽率为74.57%,仅高于CK2.89%,说明太空环境对草地早熟禾种子发芽率影响不大。但太空环境处理后,叶片数、分蘖数和株高的变异幅度分别为2～81 片、0～26 个和3～155mm,变化范围明显扩大。平均叶片宽度和最大叶片宽度分别达到2.43mm 和5.5mm,宽于对照0.47mm 和2.3mm。在1293 株处理植株中,根据形态学指标进行筛选,初步确定3 株突变植株,快速生长突变植株（PM₁）、皱叶矮化突变植株（PM₂）和嵌合体突变植株（PM₃）。分株繁殖成为株系,进行下列研究: 对太空环境处理后草地早熟禾变异株系叶片的外观形态、表面结构、解剖结构和叶肉细胞的超微结构进行了观察和测量。结果表明,3 个突变株系叶片均明显增宽、厚度减小;叶肉细胞的平均直径明显减少。PM₁ 株系表皮细胞的平均直径与CK差异不显著,PM₂和PM₃株系表皮细胞的平均直径则比CK明显减小。进一步分析表明,PM₁、PM₂和PM₃株系叶片宽度增加主要是由于细胞数目的增加;而叶片厚度减小的原因是叶肉细胞变小。太空环境也使草地早熟禾叶片表面结构发生了改变。三个突变株系的叶片气孔密度增大,气孔面积减小,单位视野中气孔所占面积比则变化不大。因此其气孔分布更密,气孔更小,有利于水分的蒸腾扩散。超微结构观察的结果表明,各突变株系叶肉细胞及叶绿体的超微结构均发生了较大的改变。三个突变株系叶肉细胞中的叶绿体均呈近球形,并向细胞中央聚更多还原

【Abstract】 Aerospace has different environmental conditions from the biosphere of the earth with respect to gravity, radiation, and magnetic field. Plant growth and development as well as genetic information may be affected under the aerospace conditions. Genetic changes caused under aerospace conditions may be used as an effective means of creating new germ plasm. The primary objective of this study was to look into the possibility of inducing mutations by exposing dry seeds of Kentucky bluegrass （Poa pratensis L.） to aerospace conditions. A secondary objective was to evaluate variations at different levels of a plant which was identified as a potential mutant caused by space condition. Dry seeds of certified ‘Nassau’Kentucky bluegrass were carried into low earth orbit for 162 hr by the Chinese spacecraft “SZ-3”, which had a flying perigee and apogee of 200 and 343 km, respectively. The control seeds were kept in a refrigerator on the earth. Temperatures within the craft were 15 to 25℃, and the air pressure was maintained at 10⁵ Pa. The seeds that were exposed to space conditions showed similar germination rates and seedling vigor as the controls. The range of leaf number, tiller number and plant height from the treated seeds were 2⁸1, 0²6 and 3¹55, respectively. The variations were larger than that of the controls. The average leaf width of the treated population was 2.43 mm, whereas that of the controls was 1.96 mm. Based on the statistical comparison of the treated and control populations in plant height, growth habit, and color, three plants were identified as potential mutants, fast growing mutant （PM₁）, wrinkle leaf mutant （PM₂）, and mosaic mutant （M₃）. The potential mutants were grown in a greenhouse for further morphological and biochemical study. Leaf blades were investigated under light microscope and electronic microscope for morphological and anatomy characteristics. The three PMs, which have wider and thinner leaf blades, all have more epidermal cells and smaller mesophyll cells compared to the control. PM₁ and PM₂ showed decreased epidermal cell height compared to the control, whereas that of PM₃ had larger epidermal cell height. The larger epidermal cells and the increase in the number of bulliform cells may have contributed to the wrinkle morphology of PM2. The stoma size and distribution of the potential mutants also were different from the control. Compared to CK, the stoma density in PM plants was increased, but the stoma size was decreased with the proportions of total stoma area to leaf area remained unchanged. The ultra structure of mesophyll cells and chloroplasts in the potential mutants showed both morphological changes and functional changes. The chloroplasts of PM1 and PM2 were spherical and located close to the center of mesophyll cells with increased starch grains. The spindle-shaped chloroplasts in the control were located closer to the cell wall with denser grana lamellae compaction and less starch grains. PM3 is a white-green mosaic in that the chloroplasts in green areas were similar to the control and the chloroplasts in white areas showed dissolved structure. The chloroplast size in PM1 and PM2 was smaller than that of CK plants. The chloroplast number and the proportion of size to mesophyll cells of PM3 were decreased. The content of the chlorophyll a and b and a/b ratio of PM1 and PM3 were the same as control. The approximated light saturation point, light compensation point and the apparent quantum efficiency of the potential mutants were all reduced, but the approximated CO2 saturation point was increased. The content of the chlorophyll a and b of PM2 was higher than that of the control but the ratio of a/b was lower than the control. The carboxylation efficiency were PM2< CK< PM3 <PM1, from lowest to highest. The control showed 14 peroxidase isoenzyme bands, while PM1 and PM2 had 13 and 14 bands, respectively. The peroxidase isoenzyme differences between PM1 and the controls are in Bands 12, 13, and 14 with Rf values of 45.2, 46.6, and 49.3%, respectively. The peroxidase isoenzyme differences between PM2 and control are in Bands 5, 10, 11, and 13 with Rf values of 24.7, 35.6, 42.5, and 46.6%, respectively. PM3 is a mosaic which is reflected by the differences of peroxidase isoenzyme bands within the tissues in Bands 4, 9, 10, 11, 12, 13, and 14. The control had 10 esterase isoenzyme bands, while PM1 and PM2 had 8 and 4 bands, respectively. The mosaic of PM3 showed esterase isoenzyme Bands 3, 5, 8, 9, 15, and 18. Proteins expressed in leaf of CK and PM2 were profiled with the techniques of proteomics. 181 proteins maintained their level, 15 proteins were up-regulated and 15 protein were down-regulated. 19 proteins were chosen to make polypeptide fingerprint and homology analysis. 14 out the 19 proteins expressed only in thecontrol and 3 proteins expressed only in PM2. 10 out of the 19 proteins were positive after homology analysis. PM2-058 was similar to Glutamine synthetase. PM2-175 was similar to Triosephosphate isomerase. CK-103 was similar to 26S proteasome regulatory complex ATPase. CK-330 was similar to ribulose 1, 5-biphosphate carboxylase/oxygenase. CK-376 was similar to Thioredoxin M precursor. CK-391 was similar to ribulose bisphosphate carboxylase. The rest four proteins had no matching proteins in the database and were unknown in functions. In general, the seeds that were exposed to space conditions showed similar germination rates and seedling vigor as the controls with some differences in morphology. The potential mutants showed differences in photosynthesis parameters, which may have contributed to the different efficiencies of light and CO2 capture. The results of this study provided preliminary insight to the physiology changes of the induced mutants from space environment. The plant materials achieved through this experiment are to be evaluated in the field for turf and forage uses.更多还原