离子束注入对狐米草几种生理生化指标的影响（简报）

N 、Zn2 、Ar 离子束注入狐米草种子 ,其萌发率均明显降低。相同剂量 ,同种离子束抑制作用随加速电压 (能量 )的升高而加强。低能离子束对已萌发种子愈伤组织诱导率无显著影响 ,但能在不同程度上提高SOD、POD、CAT活性。多数离子束处理的狐米草愈伤组织中可溶性蛋白含量增加     

低能N＋离子束辐照甜叶菊种子的当代效应研究

用不同剂量低能N＋离子注入甜叶菊种子后,观察并记录种子发芽率、幼苗和移栽植株性状及糖苷含量的影响.结果表明低剂量的氮离子束能促进甜叶菊发芽率,高剂量则抑制其发芽率;随着辐照剂量的增高,移栽植株株高、糖苷含量等主要指标出现了先下降后升高的＂马鞍型＂曲线;经辐照后出现了植株高、叶片多、叶面积大、糖苷含量高的有益变异,为进一步品种选育和诱变机理研究奠定基础.     

低能离子束促进小麦copia-反转录转座子的转录与转座

LTR-反转录转座子是真核基因组重要的组成部分,能通过RNA中间体完成在基因组上的转座。小麦种子受低能氮离子束注入后能促进其反转录转座子的转录,经不同剂量的氮离子束注入的种子发芽24h和48h后,其中的copia-反转录转座子的转录都有不同程度的提高,最高可达到对照的40倍。用基于反转录转座子扩增多态性和反转录转座子微卫星扩增多态性2种分子标记技术扩增经低能氮离子注入后的小麦DNA,指纹图谱显示出了一定的多态性,这说明低能氮离子束激活了小麦中反转录转座子的转座活性。转座子转录活性的增强可调节其邻近基因的表达和mRNA的拼接,反转录转座子插入到基因组上新的位点后,使基因组上的基因发生了重排,这种重排可能表现为植物表型的改变。因此,推测反转录转座子的转录活性提高和转座激活是产生低能离子束注入生物效应的重要原因之一。     

N+离子注入对干旱胁迫条件下甘草幼苗的SOD酶和CAT酶活性及丙二醛含量的影响

以低能氮离子束为诱变源,对甘草种进行注入处理后,以萌发的幼苗为材料对其在干旱胁迫条件下保护酶活性及MDA含量变化进行研究.结果表明注入后甘草种的存活率呈现马鞍形曲线变化,其中在4.1×1016N+/cm2剂量处达到鞍点,在剂量4.6×1016N+/cm2处存活率高于对照.在干旱胁迫下,随着胁迫时间的延长,离子束注入后萌发的幼苗MDA含量明显低于对照.酶活结果显示,在干旱胁迫后期,剂量4.6×1016N+/cm2处理后的甘草幼苗SOD和CAT酶活性都高于对照,说明该注入剂量处理甘草种有助于提高甘草幼苗的抗旱性能,SOD同工酶结果也证明该剂量的离子注入对干旱胁迫下同工酶谱带有所影响.     

氮离子注入对仿栗种子某些生理特性的影响

采用不同剂量的氮离子注入仿栗种子内,研究氮离子束注入仿栗种子后对其丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和硝酸还原酶(NR)的影响。结果表明:氮离子注入仿栗种子后,MDA含量明显降低;SOD和CAT活性随着离子束剂量的增加,均呈现先下降再上升后又下降的趋势,且均在8.6×1015N /cm2剂量下达到峰值;低剂量N 注入能提高硝酸还原酶的活性,高剂量下NR活性受到一定的抑制。     

低能氩离子注入对甜瓜幼苗抗氧化系统的影响

就低能氩离子注入对甜瓜幼苗抗氧化系统的影响进行研究,使用不同剂量的离子注入甜瓜种子,结果表明,不同剂量离子注入后伽师瓜、皇后品种的超氧化物歧化酶(SOD)分别在5×1016Ar /cm2、4×1016Ar /cm2剂量时酶活性最大,之后下降。抗坏血酸过氧化物酶(ASP)的活性的变化趋势与超氧化物歧化酶相似,分别在6×1016Ar /cm2、4×1016Ar /cm2剂量时酶活性最大。抗坏血酸和类黄酮的含量都有不同程度的上升,说明离子注入能诱导甜瓜幼苗抗氧化系统的生物合成。     

氮离子束注入大麦种子的细胞生物学效应

本文研究了用３０ＫｅｖＮ＋离子束注入大麦干种子后其Ｍ１代的细胞生物学效应。研究结果表明,低剂量的Ｎ＋离子注入对大麦种子的萌发及Ｍ１胚根、胚芽细胞的有丝分裂有明显的促进作用。离子注入均能诱发胚根细胞和胚芽细胞的染色体畸变和核畸变,呈现微核、双核、小核、桥、断片和落后染色体等多种类型。并在２×１０１６Ｎ＋／ｃｍ２－８×１０１６Ｎ＋／ｃｍ２剂量范围内,注入剂量与畸变率之间有显著的正相关,但到１×１０１７Ｎ＋／ｃｍ２后畸变率却反而下降。研究结果还显示胚芽细胞较胚根细胞对氮离子束更为敏感。     

低能离子束生物技术的应用

自从我国科学家发现离子注入生物学效应后,低能离子束生物技术的研究就在我国率先兴起。随后,越来越多的科学家基于低能离子与生物体之间存在的能量沉积、动量传递、质量沉积及电荷中和与交换的相互作用,对生物体内的遗传物质进行加工、修饰、重组,开辟了农作物和微生物等遗传改良及转基因的新方法。本文简要介绍了低能离子束生物技术产生的背景、低能离子束与生物体之间相互作用的机理和特点以及目前低能离子束在诱变育种和转基因等生物技术领域的研究进展,并展望了离子束技术在藻类基因工程方面的发展潜力。     

低能离子注入对大豆种子吸胀冷害的影响

本文分别从浸种液中无机离子的浓度、可溶性糖的浓度以及溶液的pH值,研究了低能离子注入对大豆种子吸胀冷害的影响。结果发现一定剂量的氮离子注入大豆种子后,其无机离子、可溶性糖、酸性物质的泄漏量均有低于对照组的趋势,而且其长势好于对照组,说明离子注入能在一定程度上减轻大豆遭受的吸胀冷害。     

超低能离子注入作物育种的一种重要机制

本文通过超低能（１１０ｋｅＶ）离子注入和同步辐射碳光辐照两种手段处理了小麦种子,经萌发在其根尖细胞中均观察到了多种类型的染色体时变,而且同对照相比,均有明显的微核率与染色体总畸变率。根据理论分析和一些有关的实验证据,超低能离子注入小麦种子,因离子本身射程非常短（＜１μｍ）,不可能直接损伤麦皮下面的胚细胞,而由注入离子在作物种子内产生的各种特征Ｘ－射线,只要剂量足够,却能达到较深的部位,通过它们的间接作用就会损伤胚细胞造成生物学效应。因此,赵低能离子注入作物种子激发产生的特征Ｘ－射线是其诱变育种的一种重要机制．     

Radiobiological effects of a low-energy ion beam on wheat

The radiobiological effects of a low-energy nitrogen ion (N⁺) beam on wheat were studied, particularly with regard to the induction of chromosome aberrations. The results demonstrated that the three test varieties showed different sensitivities to ion implantation, and a higher dose of ion implantation had a marked effect on the germination and survival rate of the seeds exposed. The germination rate and survival rate curve basically followed a similar trend in the same variety. Cytological analysis indicated that ion beams were effective in producing chromosome aberrations. The frequencies of mitotic or meiotic cells with chromosome aberrations increased linearly with increasing doses. The aberration types included, for example, acentric fragments, chromosome deletions, lagging chromosomes, chromosome bridges and micronuclei. In the root tip cells, aberrations chiefly consisted of acentric fragments and deletions. Chromosome bridges and lagging chromosomes were the main aberration phenomena observed in the pollen mother cells. The highest frequencies of root tip cells and pollen mother cells with chromosome aberrations were 15.2% and 39.8%, respectively. Changes in morphology and mutant were also observed in the plants derived from exposed seeds. Received: 10 April 2000 / Accepted: 10 October 2000     

离子注入烟草种子引起的M1代变异分析

利用随机引物扩增ＤＮＡ（ＲＡＰＤ）技术及ＳＤＳ－聚丙烯酰胺蛋白电泳技术,对３０ｋｅｖＮ＋离子注入后的烟草Ｍ１代ＤＮＡ及叶片水溶性蛋白进行分析,通过ＲＡＰＤ反应,检测到ＰＣＲ条带的缺失和增加,而对照植株未发现条带明显变化,并且条带变异率随剂量的增加而上升。６０次的剂量对烟草（红花大金元）诱变效果较好,有相对较高的成活率和变异率。还发现Ｎ＋离子注入后,Ｍ１代叶片水溶性蛋白与对照相比有明显变异;Ｍ１代植株株高普遍高于对照,并出现少数表型变异。     

低能氮离子注入对决明子的生物效应研究

用低能氮离子注入决明子种胚,种子浸泡液电导率显著增加,发芽势和发芽指数显著降低,幼苗主根长度减少,平均鲜重和活力指数显著降低.直接接受离子注入的种胚,其SOD酶活性随注入剂量的增加呈现出先下降再轻微上升的趋势.而没有直接接受离子注入的胚乳,其SOD酶活随注入剂量的增加呈马鞍形曲线.     

低能N+离子束注入对不同染色体组倍性水稻幼苗期生理特性的影响

以2份水稻二倍体及其相应的同源四倍体为试验材料,采用3种不同剂量的低能N+离子束对其种胚进行注入处理,对其出芽率、成苗率以及幼苗期5种主要生理指标:超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、丙二醛(MDA)和可溶性糖进行初步测定。结果表明:随着辐射剂量的增加,试验材料的出芽率和成苗率均呈下降趋势,在最高剂量处理条件下(5.0×1017N+/cm2)试验材料的出芽率、成苗率与对照相比差异达极显著水平(P<0.01)。二倍体材料幼苗SOD、POD、CAT的活性均呈先上升后下降的趋势,并在3.0×1017N+/cm2的剂量下达到最高,而四倍体材料幼苗SOD、POD、CAT的活性则呈先上升后下降再上升的趋势,并在1.0×1017N+/cm2的剂量下达到最高。二倍体材料幼苗MDA含量的变化呈先下降再上升的趋势;四倍体材料幼苗MDA含量的变化呈先下降后上升再下降的趋势。两种染色体组倍性水稻材料中可溶性糖含量在各处理组间差异不是特别显著,但均低于空白对照组。由此可见,不同剂量的低能N+离子束会对试验材料的出芽率、成苗率以及幼苗期的主要生理特性产生显著的影响,且不同染色体组倍性材料间也存在一定的差异。     

Biological effects of low-energy C ion implantation on sesame (Sesamum indicum L.)

Field cultivation experiments on white sesame (Sesamum indicum L.)seeds implanted with low-energy C ion showed that different dosages of C ion implantation produce different biological effects.Sesame plants in 6 different dosage groups with C ion density respectively at 1×1011,1×1012,1×1015,5×1015,1×1016,5×1016 ion/cm2 were superior to the control group in plant height,leaf number,stalk diameter and leaf size.Further,sesame plants in these groups flower and seed earlier than those in the control group,and single plant yield also increased.Of all the groups,the 5×1015 ion/cm2 dosage group yielded the best effect,whereas the 1×1017/cm2 dosage group showed an evident inhibitory effect of ion implantation on the germination and growth of the sesame seeds.     

Nitrate, a signal relieving seed dormancy in Arabidopsis

Nitrate is an important nitrogen source for plants, but also a signal molecule that controls various aspects of plant development. In the present study the role of nitrate on seed dormancy in Arabidopsis was investigated. The effects of either mutations affecting the Arabidopsis nitrate reductase genes or of different nitrate regimes of mother plants on the dormancy of the seeds produced were analysed. Altogether, data show that conditions favouring nitrate accumulation in mother plants and in seeds lead to a lower dormancy of seeds with little other morphological or biochemical differences. Analysis of germination during seed development indicated that nitrate does not prevent the onset of dormancy but rather its maintenance. The effect of an exogenous supply of nitrate on seed germination was tested: nitrate in contrast to glutamine or potassium chloride clearly stimulated the germination of dormant seeds. Data show, moreover, that the Arabidopsis dual affinity nitrate transporter NRT1.1 (CHL1) may be involved in conveying the nitrate signal into seeds. Thus, nitrate provided exogenously or by mother plants to the produced seeds, acts as a signal molecule favouring germination in Arabidopsis. This signalling may involve interaction with the abscisic acid or gibberellin pathway.     

氮离子注入彩棉种子引起M1代的变化

不同剂量低能氮离子注入彩色棉种子,发芽率随剂量增大呈现出马鞍形曲线;对M1代主要经济性状测定,铃重、衣分、马克隆值有明显变异,在12×1016 N+/cm2剂量下改良效果较好,但离子注入对纤维长度和纤维强度以负影响为主;处理组POD酶和CAT酶活性都较对照组增高.     

沿重离子贯穿深度的番茄干种子辐射生物学效应研究

本文采用80MeV/u的^12C^6 辐照番茄干种子,研究处于不同离子贯穿深度番茄干种子的辐照生物学效应,检测其生理生化指标。结果表明：辐照后不同贯穿深度上番茄种子的发芽势与物理剂量对应,第8层样品（对应于碳离子在水中的贯穿深度为15mm）出现峰值76.7％,发芽率随离子入射深度的变化不明显;不同贯穿深度辐照样品的根尖细胞微核率也与物理剂量相对应,在第6、7层样品中出现峰值0.257％;另外,辐照样品幼苗茎叶的一氧化氮合酶（NOS）活性、谷胱甘肽（GSH）含量及总抗氧化力在第9层出现峰值,谷胱甘肽过氧化物酶（GSH-PX）活性在第7-8层出现峰值,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性的变化与重离子贯穿深度没有明显的相关性。总而言之,本工作发现辐照品的多个生理生化指标均与入射离子的微剂量分布相对应,即存在生物效应峰。     

Germination Promotion of Loblolly Pine and Baldcypress Seeds by Stratification and Chemical Treatments

The effects of 4 chemicals on the germination promotion of stratified and unstratified seeds of loblolly pine (Pinus taeda) and baldcypress (Taxodium distichum) were studied. The chemicals used were gibberellic acid, kinetin, potassium nitrate and thiourea, each at 3 different concentrations. Stratification promoted the germination of both seed species. Certain concentrations of gibberellic acid, potassium nitrate and thiourea improved the germination of unstratified loblolly pine and baldcypress seeds while kinetin had no stimulatory effect. All 4 chemicals at specific concentrations promoted the germination of loblolly pine seeds stratified for a short period of time. Considering both speed and completeness of germination, best results were obtained when 21-day stratified seeds were treated with either gibberellic acid (100 mg/1) or kinetin (10 mg/1). In baldcypress, on the other hand, none of these chemicals had any stimulatory effect on the germination of stratified seeds. Germination of both species of seeds was either partially or completely inhibited by the highest concentration of thiourea (30,000 mg/1) used.