缺体小麦与黑麦杂种幼胚愈伤组织再生植株的染色体变异

对中国春6A缺体小麦与黑麦杂种幼胚愈伤组织不同无性世代再生植株体细胞染色体鉴定结果表明,随着愈伤组织培养时间的延长,再生植株染色体变异频率及变异范围明显增加。在分化的共计224株再生植株中,发生染色体变异的植株为80株,占35.7％,其中有3株为染色体嵌合株,1株发生了染色体结构变异。     

缺体小麦与黑杂种幼胚愈伤组织再生植株的染色体变异

对中国春６Ａ缺体小麦与黑麦杂种幼胚愈伤组织不同无性世代再生植株体细胞染色体鉴定结果表明,随着愈伤组织培养时间的延长,再生植株染色体变异频率及变异范围明显增加。在分化的共计２２４株再生植株中,发生染色体变异的植株为８０株,占３５．７％,其中３株为染色体嵌合株,１株发生了染色体结构变异。     

小麦体细胞再生株（R1）的染色体变异分析

本文研究了普通小麦(Triticum aestivum)、“宁麦三号”等5个基因型的体细胞再生株(R_1)减数分裂各期的染色体异常行为。结果表明:再生株 R_1代有丝分裂时表现为染色体数量上的变异,最常见的有2n-2类型,其次是2n-1类型,也有少数为2n 1和2n-4等变异类型;再生株 R_1花粉母细胞减数分裂过程中出现单价体、多价体、染色体桥、落后染色体、断片和微核等异常现象,并与各基因型细胞遗传程度上差异有关。     

高粱幼胚培养及再生植株变异的研究

高粱幼胚接种在MS培养基上培养。授粉后9—12天的幼胚是最好的诱导分化时期。所试验的20个不同高粱基因型,从愈伤组织分化再生植株的能力是不同的。这种分化能力是可遗传的。从401-1品种的5个授粉后9—12天幼胚的小盾片愈伤组织分化的158株再生植株(R_0),大部分是正常的,但也出现了一些变异株。R(?)的变异株在R_1没有复现,但从某些R_0正常株而产生的R_1穗行,出现了矮株和不育株变异。     

枸杞抗羟脯氨酸细胞变异系筛选及其耐盐特性的研究

试验以枸杞(Lycium barbarum L.)成熟胚诱导的胚性愈伤组织为材料研究了：(1)^60Co—γ射线诱变处理对愈伤组织的影响;(2)耐羟脯氨酸(HYP)愈伤组织变异系的筛选;(3)耐HYP愈伤组织变异系的耐盐性及稳定性分析;(4)耐HYP愈伤组织变异系生理生化特性;(5)变异系的分化和再生苗的生理生化特性。初究结果表明：由胚性愈伤组织经30Gy的^60Co—γ辐射处理,在含16mmol／L HYP选择培养基和无HYP培养基上交替培养4代,分离出耐HYP的愈伤组织变异体;该变异体游离脯氨酸含量比对照高3．3倍,其再生植株叶片游离脯氨酸比对照高13．5倍。     

玉米胚性愈伤组织的长期继代及其染色体分析

对５种基因型幼胚诱导的愈伤组织继代培养表明,玉米胚性愈伤组织的长期继代受基因型,培养基成分,激素,培养条件的影响。适时继代,逐代筛选对胚性保持起重要作用。适当降低培养温度（１２±２℃）有利于愈伤组织的保存和胚性保持,可以减少愈伤组织长期继代所需的物质和工作量。长期继代培养的胚性愈伤组织,胚状体发生能力和植株再生率无显著变化,但正常苗的再生频率显著下降。观察愈伤组织细胞染色体发现：（１）基因型对不同倍性细胞的比例有明显影响。（２）随着继代时间的延长,二倍体细胞下降,四倍体和非二倍体细胞增多。（３）愈伤组织中出现多种染色体结构变异,这些结构变异有可能导致非整倍体细胞的形成。     

春小麦体细胞无性系变异的研究

利用RAPD技术检测春小麦愈伤组织和再生植株在离体培养过程中产生的变异,对培养不同时期的愈伤组织、再生植株检测结果表明,在小麦离体培养愈伤组织和再生植株中,RAPD谱带发生变化,表明发生了体细胞无性系分子水平变异．且具有明显的规律性和变异特点：杂交B代幼穗培养获得的愈伤组织发生变异的频率高于遗传稳定品种幼穗培养获得的愈伤组织。在愈伤组织培养75d时,在RAPD电泳图谱反映出高频率的亲本谱带缺失和非亲本谱带增加。不同基因型或外植体诱导的愈伤组织和再生植株中出现了相同的变异。与愈伤组织相比．再生植株中检测到的变异频率更高。不同外植体离体培养获得的再生植株,即使表型上没有观察到变异,但从RAPD图谱上却反映出变异的发生。表明RAPD技术可以快建方便地检测组织培养每个阶段出现的DNA水平变异。     

二甲戊灵对离体大蒜染色体的加倍研究

在MS分化培养基中分别添加不同浓度的秋水仙素和二甲戊灵,以 "改良蒜" 的蒜瓣基部为外植体诱导愈伤组织染色体变异并再生植株,观察根尖细胞染色体数和叶片下表皮保卫细胞特征检测诱变效果.结果表明:大蒜染色体数变异受诱变剂浓度和处理持续时间的影响,诱变剂高浓度和短时间处理均有利于大蒜愈伤组织的分化;添加0.1%秋水仙素处理5 d,愈伤组织存活率为80.7%,分化率为78.1%,四倍体的诱导率为4%;添加 100 μmol/L二甲戊灵处理5 d,愈伤组织存活率为100%,四倍体的诱导率为6%.对根尖细胞染色体和叶片下表皮气孔数目和大小观察显示,诱变株具有四倍体的基本特征.说明二甲戊灵能在离体条件下有效诱导大蒜产生四倍体,可替代秋水仙素对大蒜染色体的加倍作用.     

小麦及缺体小麦与黑麦杂种幼胚愈伤组织在长期继代中的染色体数量变异

对中国春及其６Ａ缺体与黑麦杂种幼胚愈伤组织在长期继代培养过程中愈伤组织的染色体数量进行了统计分析,结果表明：中国春×黑麦和６Ａ缺体×黑麦杂种幼胚愈伤组织在继代培养的前６０ｄ内细胞染色体数目分别稳定在２ｎ＝２８和２７;随着继代培养时间的延长,其染色体数量均发生变异主要表现为染色体数的减少;在第４２０ｄ至５４０ｄ培养期间两个组合愈伤组织丢失染色体的细胞比率明显增加,同时也发现了个别超出正常染色体数的细胞。第５４０ｄ后的愈伤组织染色体数量变异基本维持在这一水平。     

小冰麦异附加系的体细胞无性系建立及其变异的研究

从7种小冰麦异附加系的幼叶和成熟胚诱导出愈伤组织,建立了体细胞无性系,获得大量试管苗,并移栽成活。实验设计了适于小冰麦异附加系组织培养的 WG 培养基。愈伤组织诱导采用二次诱导方法。第一诱导培养基为 WG_2附加4mg/1 2,4-D、1mg/1 NAA。第二诱导培养基为 WG_2附加2m//1 2,4-D、0.5mg/1 NAA,和0.25mg/1KT。分化培养基为 WG_3附加0.5mg/1 KT、1mg/1 NAA 和100mg/1 Ad。再生植株的染色体检查表明,异附加系无性系的染色体数变异明显。保持2n=44的再生植株只有34.4%,而且变异植株中回复到2n=42的植株较多。再生植株中约有1/2发生了形态变异。在变异植株的花粉母细胞中观察到染色体的交换、易位等结构变化。特别在愈伤组织细胞中观察到多条染色体融合成多着丝点染色体和体细胞的染色体交叉,说明无性系中发生了染色体的交换和易位。     

小麦成熟胚无性系后代的性状表现

观察了来源于小麦成熟胚培养再生植株中R_2代无性系农艺性状的变异。结果表明;R_2无性系的株高、穗粒数、千粒重、抽穗期和穗长都发生了不同变异,每个农艺性状的变异频代率较高,并且穗系间也有变异,还对无性系的变异和利用进行了讨论。     

Analysis of Chromosome Variation of Plants (R1) Regenerated from Somatic Cell of Wheat (Triticum aestivum)

Abnormal behaviors were observed throughout the whole melosis process of regenerated plants (R0 from somatic cell of Triticum aestivum cv. Ningmai 3. There was variation of chromosome numbers. The type of 2n–2 was frequently found, then the type of 2n–l, while the 2n+l and 2n–4 types were rarely observed. Anomalous ph-nomena such as univalent, multivalent, lagging chromosome, chromosome bridge, fragment and micronuclei were emerged at the meiotic stage of pollen mother cells of the regenerated plants (R1). These variations were different in degree in the 5 tested genotypes.     

不定胚再生植株的染色体数目变异

本实验以甜瓜“小麦瓜”和“青皮绿肉”品种为试材,经不定胚诱导再生植株。分别调查了不同继代培养时间后形成再生植株的染色体数目,并将之与对照染色体数目相比较,发现通过诱导不定胚所得到的再生植株中存在着一定的变异,而且经过不同继代培养时间后,所得到的不定胚再生植株的变异程度不同,随着时间的增加,染色体数目的变异率从3.3%增加到30%,变异幅度也从2n=23~24增加到2n=13~48。从而得出结论：不定胚再生植株染色体数目变异程度随着培养时间的增加而增加;培养时间在1~2个月内所得到的不定胚再生植株的变异较少。此外,不定胚再生植株的染色体数目变异程度也因品种而异。 Abstract:Chromosomal number of different of somatic embryos regenerated plants were investigated in melon variety “xiaomaigua” and “Qingpilurou”.Certain variations of chromosomal number were found among the regenerated plants compared with normal sample,and range of variation covered from 2n=23～24 to 2n=13～48 with the increase of generation,the rate from 3.3% to 30%.The results indicated that degree of variation in chromosomal number of somatic embryos regenerated melon plants increased with the time of culture,and those cultured in one to two months had the least variation.It was also found that degree of chromosomal number variations varied with melon varieties.     

Somaclonal variation in tomato: effect of explant source and a comparison with chemical mutagenesis

Summary Plants were regenerated from leaf, cotyledon, and hypocotyl explants of tomato cv Moneymaker. Various phenotypic alterations were observed among regenerated plants (R₁), but were not transmitted to the progenies, except for ploidy variation. Variation in ploidy level, mainly tetraploidy, occurred in R₁ plants and their R₂ progenies, and the frequency of polyploid plants depended on the explant source. More than 50% of the regenerants derived from hypocotyl explants were found to be polyploid. A correlation was observed between the percentage of polyploid cells present in the explant material in vivo and the frequency of polyploid plants. Several monogenic mutations were recovered in the R₂, four of which were shown to be allelic to known, recessive, single-gene mutants. No significant effect of explant source or duration of tissue culture period on mutant frequency or spectrum was found. For several mutant types that could be scored unambiguously, somaclonal variation was compared to variation induced by treatment of seeds with ethyl methane sulphonate (EMS). The results showed that the mutant frequencies were higher after EMS treatment than those generated through tissue culture. With respect to the mutant spectrum, no clear differences were observed between the spectra obtained after EMS treatment and those after tissue culture. However, tissue culture gave rise to polyploid plants, whereas no ploidy variants occurred after EMS treatment.     

Detection of somaclonal variation of cotton (Gossypium hirsutum) using cytogenetics, flow cytometry and molecular markers

Two protocols of plant regeneration for cotton were adopted in this study, namely, 2, 4-D and kinetin hormone combination and IBA and kinetin hormone combination. Twenty-eight embryogenic cell lines via somatic embryogenesis and 67 regenerated plants from these embryogenic calli were selected and used for random amplified polymorphic DNA (RAPD), simple sequence repeat (SSR), chromosomal number counting, and flow cytometric analysis. The roles of RAPD and SSR markers in detecting somaclonal variation of cotton (Gossypium hirsutum L.) were evaluated. Two cluster analyses were performed to express, in the form of dendrograms, the relationships among the hormone combinations and the genetic variability. Both DNA-based techniques were able to amplify all of the cell clones and regenerated plantlets genomes and relative higher genetic variation could be detected in the culture type with 2, 4-D and kinetin hormone combination. The result suggested that 2, 4-D and kinetin hormone combination could induce relative high somaclonal variation and RAPD and SSR markers are useful in detecting somaclonal variation of regenerated cotton plants via somatic embryogenesis. Chromosome number counting and flow cytometry analysis revealed that the number of chromosomes and ploidy levels were nearly stable in all regenerated plants except two regenerated plantlets (lost 4 and 5 chromosomes, respectively) which meant that cytological changes were not correlated with the frequency of RAPD and SSR polymorphisms. This result also might mean that the cell lines with variation of chromosome numbers were difficult to regenerate plants.     

小麦再生植株的变异研究 Ⅱ.再生植株当代(R_1代)的细胞学和形态学变异

再生植株具有高频率的染色体异常,其中有20.61％表现为染色体数量变异,最常见的为2n—1类型,其次为2n—2类型,也有2n 1、2n—3个体以及染色体数嵌合株。再生植株减数分裂各期均有染色体异常行为,可以见到的有落后染色体、染色体桥、断片、二分体延迟、微核,还有粗线期十字型配对等结构变异,以及五分体、六分体和畸型四分体等异常现象。微核率随培养时间延长而增加,可用作染色体伤害的一个指标。再生植株R_1代存在着许多形态学变异。性状变异与染色体数目变异没有明显关系。     

大豆体细胞胚系培养及其微卫星DNA稳定性研究(简报)

植物离体培养是植物基因操作中的重要一环,也是植物个体发育研究中基因表达研究的有益参考体系。在继代培养过程中发生的遗传变异有时会使再生植株丧失优良的性状而需加以控制和避免。为此,首先需要了解培养过程中的遗传变异情况。     

Assessment of somaclonal variation in <Emphasis Type="Italic">Dieffenbachia</Emphasis> plants regenerated through indirect shoot organogenesis

The occurrence of somaclonal variation among regenerants derived through indirect shoot organogenesis from leaf explants of three Dieffenbachia cultivars Camouflage, Camille and Star Bright was evaluated. Three types of somaclonal variants (SV1, SV2, and SV3) were identified from regenerated plants of cv. Camouflage, one type from cv. Camille, but none from cv. Star Bright. The three variants had novel and distinct foliar variegation patterns compared to cv. Camouflage parental plants. Additionally, SV1 was taller with a larger canopy and longer leaves than parental plants and SV2. SV2 and SV3 did not produce basal shoots (single stem) but basal shoot numbers between SV1 and parental plants were similar ranging from three to four. The variant type identified from regenerated cv. Camille had lanceolate leaves compared to the oblong leaves of the parent. This variant type also grew taller and had a larger canopy than parental plants. The rates of somaclonal variation were up to 40.4% among regenerated cv. Camouflage plants and 2.6% for regenerated cv. Camille. The duration of callus culture had no effect on somaclonal variation rates of cv. Camouflage as the rates between plants regenerated from 8 months to 16 months of callus culture were similar. The phenotypes of the identified variants were stable as verified by their progenies after cutting propagation. This study demonstrated the potential for new cultivar development by selecting callus-derived somaclonal variants of Dieffenbachia.     

Effect of 2,4-dichlorophenoxyacetic acid concentration on somatic embryogenesis and heritable variation in soybean [Glycine max (L) merr.]

Summary The frequency and quality of embryogenic response from cotyledons of immature zygotic soybean embryos varied with 2,4-dichlorophenoxyacetic acid (2,4-D) concentration in the culture medium. The frequency of variants among progeny of regenerated plants decreased with an increase of 2,4-D concentration. Teratogenic effects on embryo morphology and development were greatest at 22.5μM 2,4-D and decreased with increasing 2,4-D. At the lowest 2,4-D concentration tested, 22.5μM, morphologically abnormal, cotyledonary-stage somatic embryos were produced. Ten percent or less of these embryos converted to plants. Over the nine genotypes tested, 40% of the families derived from plants regenerated under a low 2,4-D concentration manifested heritable variation. In contrast, embryogeny was suppressed at the globular stage by the highest 2,4-D concentration tested, 200μM. Eighty to one-hundred percent of the embryos organized under this latter 2,4-D level converted to plants. Only 3% of the families from the progeny of plants regenerated under a high 2,4-D concentration exhibited heritable variation. This is Journal Paper No. J-14217 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 2974. The mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the United States Department of Agriculture or Iowa State University and does not imply its approval to the exclusion of other products that may be suitable. This work was supported, in part, by American Soybean Association grant no. 400-46-73-15-2763.     

Isozyme Variability in Plants Regenerated from Calli of Cereus peruvianus (Cactaceae)

Morphological and isozyme variation was observed among plants regenerated from callus cultures of Cereus peruvianus. Different morphological types of shoots (68%) were observed in 4-year-old regenerated plants, while no distinct morphological variants were observed in plants grown from germinated seeds. Isozyme patterns of 633 plants regenerated from calli and of 261 plants grown from germinated seeds showed no variation in isocitrate dehydrogenase isozyme, and the differential sorbitol dehydrogenase, alcohol dehydrogenase, malate dehydrogenase, acid phosphatase, and peroxidase isozyme patterns observed in regenerated plants were attributed to nonallelic variation. Allelic variation was detected at three isoesterase loci. The proportion of polymorphic loci for both populations was 13.6% and the deviation from Hardy–Weinberg equilibrium for the Est-1 and Est-7 loci observed in somaclones was attributed to the manner in which the regenerant population was established. The high values for genetic identity among regenerant and seed-grown plant populations are in accordance with the low levels of interpopulation genetic divergence. In somaclones of C. peruvianus, morphological divergence was achieved within a short time but was not associated with any isozyme changes and also was not accompanied by biochemical genetic divergence.