【作者】 肖梅；

【导师】 李庄； 韦文楼；

【作者基本信息】 广西大学 ， 理论物理， 2004， 硕士

【摘要】 无核沙田柚是国际市场上优质果品，采用激光诱变手段已经得到了无核、少核的沙田柚新品种。 本文收集和总结了多年来大田生产的实验样本与相关记录数据，从生物学效应和物理理论应用两个方面，对沙田柚的无核化做了实验观察、分析以及理论计算方面的探讨，详细论述了激光诱变的作用机理。 在生物学方面，从植物的形态学、细胞学、遗传学等角度，做了形态变异观察，讨论了花粉育性与激光诱变产生无核之间的联系，分析了沙田柚雌雄配子体的生长状况，做了酶谱分析，染色体结构和数目的研究，以及基因分析。 在理论分析方面，建立了激光作用DNA突变的理论模式分析，该分析主要的量子计算采用Rein等人对DNA氢键系统的计算结果，用曲线拟合最小二乘法处理Rein等人的数据，求出双势阱中间势垒的近似方程，再用量子力学势垒贯穿系数公式计算DNA氢键系统的质子贯穿系数，将结果用以解析激光作用对DNA突变率的影响，从理论上对突变的机理进行详细且合理的解析。 现将主要结果与结论介绍如下： 广西大学硕士学位论文1.生物学实验结果为:诱变组与对照组相比，沙田袖雌雄配子体发 育基本一致，而酶活性、花粉育性及在ONA分子水平上都出现差 异。说明激光诱变可引起物种性状的改变。2.复合激光处理后的酶谱呈现重合性，检测激光诱变沙田袖的第二 代的酶谱与对照组相比仍发生变化，且第二代的无核性状基本稳 定。说明激光辐照育成的无核果的酶活性发生了变化，其无核性 状具有遗传的可能。3.沙田袖的种子是通过花粉授粉使胚珠受精，并在果实内发育而来 的，如果激光辐照后花粉出现败育性，种子就可能大大减少。可 见，沙田袖出现无核、少核与花粉败育情况有密切关系，但花粉 败育率高并不能百分之百地肯定是无核或少核，内在原因的高花 粉败育率才能出现无核、少核果。因此，雄性不育可能是产生无 核、少核的原因之一。4.经激光诱变的芽，长出无核果的枝条的嫩叶的DNA特定序列，产 生了与所用引物对应的突变，引物序列互补，出现了多态性片段， 与对照组的相比，存在遗传性差异，导致在该枝条上长出无核果。5.实验中发现，无核、少核沙田袖的坐果率低于多核沙田袖，果皮 变厚。但已获得无核、少核，·可食率增加等可贵的经济性状。6.低功率激光影响生物体及其使生物体产生遗传变异的主要机制在 于:激光的光效应和电磁场效应，并且任一波长的激光都可产生 生物学效应。7.物种在自然条件下的变异率极小，产生无核的几率更小，经激光广西大学硕士学位论文作用后，突变几率有了明显的提高，但数量级仍然很小。为使激光诱变生物研究更具有规范性、可重复性，减少盲目性，应注意诱变参数的选择。更多还原

【Abstract】 Shatian Pumelo is a kind of high quality fruit in the world market. Our group of experiment have got the seedless fruit by the means of Laser-mutagenesis.Most experimental swatches and data are included in this paper. Many experiments are done and analyzed in two aspects of biological and physical.From biological aspect, we observed the modality aberrance, discussed the connection between pollen abortion and Laser-mutagenesis of seedless Shatian Pumelo in morphologic, cytology, genetics and so on. We observed and analyzed the male and female embryology’s development, enzymology, chromosome structure and number, gene et.cl.From theory analysis aspect, we analyzed the theoral mode of aberrance DNA acted by Laser. The main quanta count was cited from Rein’s DNA results. We disposed the data by the means of Curve Least Square, made out proximate equation, and then calculated DNA H-bond system proton trans-coefficient. The result can be used to parse Laser’sact infection on DNA mutation rate. The mutation mechanism wasexplained at the part of theory.The following is our results and conclusions:1. The biological experimental result: the contrast between experiment and wildness Shatian Pumelo is that the male and female embryology’s development is normal, enzymologist work character, pollen abortion and DNA are different. The result shows that laser can lead species mutation.2. Multiplex Laser makes enzymologist chart super positional. Enzymologist chart has changed, and the second generation’s seedless character is steady on the whole. The result shows that the inherited character by Laser-mutagenesis is possible.3. Shatian Pumelo’s ovule impregnated through pollen pollination, and then developed into seed in fruit. If abortion appeard on pollen after Laser- irradiation, the number of seed can be reduced greatly. It’s evident that the seedless is connected with pollen abortion. But it is not sure that pollen abortion can bring seedless absolutely. Inter reasonal pollen abortion can bring seedless fruit. So pollen abortion is possible only one of reasons that bring seedless fruit.4. The Laser-mutagenesis seedless fruit’s burgeon leafage DNA sequence is changed. Contrast with the weedless, it has genetic difference. So it grows into seedless fruit.5. Seedless Shatian Pomelo’s fruity ratio is lower, the seed capsule is thicker. But we have got the seedless.character.6. The main mechanism that low-power Laser affected on organism and got variation is Laser phonic and electromagnetic effect. Any wavelength laser can bring biological effect.7. Species variation ratio is very little in nature condition, the ratio can be rised by Laser but still little. So we should choose laser bean parameter in order to avoid blindness work.更多还原