嫁接导致的绿豆可遗传性变异及其在绿豆育种中的应用

植物嫁接可以导致接穗的后代中有可遗传性变异的发生.我们将绿豆(Vigna radiata (L.) Wilczek)的幼苗嫁接在红薯(Ipomoea batatas (L.) Lam.)的茎上, 维护其生长至结实.将收获的绿豆种子连续几代播种于普通环境时, 其后代中出现了明显的遗传变异.这些变异在未经嫁接的绿豆接穗品系中并不出现.为了研究这种嫁接诱导变异现象可能的机理, 我们对变异品系的细胞质和细胞核DNA进行了分析.结果显示,在原绿豆和变异品系之间未发现细胞质DNA的RFLP(限制性酶切片段多态性)差异.而细胞核DNA却发生了高频率的序列重组.同时,本研究没有发现砧木与接穗间基因转移的迹象.根据以上事实,我们推测远缘嫁接变异很有可能是嫁接生长逆境诱导的抗逆变异.     

巴西橡胶树嫁接接合区接穗和砧木径向生长差异的研究

采用树皮嫁接后不锯砧和光镜观察的方法,研究了巴西橡胶树(Hevea brasiliensis)嫁接后8个月的接合区接穗和砧木木质部径向生长的差异现象。结果表明,接合区接穗木质部的径向生长普遍地小于砧木,这种生长差异是由接穗和砧木亲本固有生长特性的差异引起的,与嫁接亲和性无关。(1)对于同一无性系,接穗的发育阶段决定其生长能力,幼态接穗新分化的木质部显著地大于老态接穗,而两类接穗旁边的砧木之间没有明显差别。(2)砧木生长势明显地影响接穗木质部的生长,砧木生长势越强,砧木和接穗的生长就越快,两者的径向差异也越大。(3)同一砧木上各品系接穗木质部生长差异取决于接穗自身的生长特性,砧木的生长不受接穗品系的明显影响。显微观察表明橡胶树的嫁接是亲和的,接穗新分化的木质部镶嵌在砧木新分化的木质部中,维管组织如导管上下连接畅通,砧穗树皮厚度一致,愈合良好。     

家蚕DNA诱导蓖麻蚕产生无洞茧

异源DNA诱导遗传性变异的研究,近年来受到广泛的重视。周光宇教授经过广泛的实地调查,认为远缘DNA片段在母本DNA复制过程中,有可能被重组而使子代出现变异。因而她提出了常规远缘杂交中,存在着DNA片段杂交的假设(周光宇等,1979),我们曾用家蚕DNA或DNA蛋白,分别注入蓖赞蚕幼虫体内,结果后代发生了幼虫皮斑性状的改变(陈元霖等,1981)。本文报告我们用家蚕DNA诱导蓖麻蚕产生无洞茧的试验结果。     

绿豆抗豆象遗传的初步研究

绿豆象(Callos0bruchun chinensis L.)是豇豆属豆类作物重要的仓库害虫.本研究通过抗豆象杂交育种后代VC1973A/TC1966 F1、F2和VC1973A/(VC1973A/TC1966 F2)BC1F1及TC1966/(VC1973A/TC1966 F2)BC1F1分离群体的遗传分析,发现绿豆抗豆象性状符合31的遗传分离规律,证明绿豆对豆象的抗性由1对显性单基因(Aa)控制,抗虫性为显性(A),感虫为隐性(a).     

绿豆抗豆象遗传的初步研究

绿豆象(Callosobruchus chinensis L.)是豇豆属豆类作物重要的仓库害虫。本研究通过抗豆象杂交育种后代VCl973A／TCl966F1、F2和VC1973A／(VCl973A／TC1966F2)BC1F1及TC1966／(VC1973A／TC1966F2)BC1F1分离群体的遗传分析,发现绿豆抗豆象性状符合3：1的遗传分离规律,证明绿豆对豆象的抗性由1对显性单基因(Aa)控制,抗虫性为显性(A),感虫为隐性(a)。     

雄性不育高粱线粒体与细胞核对热激的反应及其与育性关系的研究

由于我们发现热激(40℃)能诱导雄性不育高粱转变为雄性可育型的现象,故进一步探讨此现象的机理,研究了在热激条件下其细胞质(取其细胞质重要遗传物质——线粒体)中及细胞核中蛋白质的变化。试验结果,发现不育系的花粉母细胞期幼穗,在热激时细胞核中出现特异的80KD热激蛋白,且能被利福霉素、氯霉素所抑制。保持系在热激时细胞核中未出现此蛋白。80KD蛋白在结合部位存在的性质与其存在于细胞核中和线粒体中的现象是一致的。这种差异说明与雄性不育有关,且其原因是由细胞核与细胞质共同作用所致。     

苎麻疫霉生物学性状遗传与变异研究

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉（PhytophthoraboehmeriaeSawada）的菌落形态、菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在3种类型：（1）在单游动孢子后代和自交后代均可稳定遗传;（2）在单游动孢子后代稳定遗传而在自交后代发生变异;（3）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂合基因控制,也可以由细胞核纯合基因控制,还可能由细胞质因子控制。试验结果还指出,苎麻疫霉的同宗配合性状在单游动孢子和单卵孢后代均可稳定遗传,表明在供试的苎麻疫霉菌株中控制该性状的遗传因子是纯合的。     

苎麻疫霉生物学性状遗传与变异研究*

在实验室条件下研究了不同地区和不同寄主来源的苎麻疫霉（PhytophthoraboehmeriaeSawada）的菌落形态、菌丝线性生长速率（以下简称为生长速率）及同宗配合性状的遗传与变异,结果指出苎麻疫霉菌落形态和生长速率的遗传存在3种类型：（1）在单游动孢子后代和自交后代均可稳定遗传;（2）在单游动孢子后代稳定遗传而在自交后代发生变异;（3）在单游动孢子后代和自交后代均发生变异。结果表明,该菌菌落形态和生长速率的遗传具有多样性,上述两性状可以由细胞核杂合基因控制,也可以由细胞核纯合基因控制,还可能由细胞质因子控制。试验结果还指出,苎麻疫霉的同宗配合性状在单游动孢子和单卵孢后代均可稳定遗传,表明在供试的苎麻疫霉菌株中控制该性状的遗传因子是纯合的。     

寡聚糖诱导悬浮培养南方红豆杉细胞的凋亡

在真菌(Fusarium oxysporum f.vasinfectum (Atkinson) Snyder et Hansen)寡聚糖诱导悬浮培养南方红豆杉(Taxus chinensis (Pilger) Rehd.var.mairei (Lemee et Lévl.) Cheng et L.K.Fu)细胞生产紫杉醇的体系中发现细胞出现凋亡,次生代谢增强.电镜观察到细胞核质和原生质出现凝集现象,液泡内出现大量的高电子致密体.核DNA经琼脂糖凝胶电泳,呈200 bp的整数倍的梯状条带(ladders);而对照组细胞核DNA完整,呈大片段,细胞完整,细胞器发达,但紫杉醇合成速率很低.加入寡聚糖后,细胞防御系统开启,细胞生长停止,次生代谢物酚类物质大量积累且次生壁加厚,多酚氧化酶活性迅速提高,苯丙烷类代谢途径的关键酶苯丙氨酸解氨酶的活性在1 h后急速提高,目的产物紫杉醇在诱导后72 h达到峰值,比对照组提高了6倍,且细胞凋亡的出现与紫杉醇合成的峰值具有时间上的一致性.     

向日葵细胞质雄性不育系线粒体基因组atpA位点的研究

对21种向日葵细胞质雄性不育(CMS)品系的线粒体基因组atpA基因位点处的DNA分子变异进行了分析和研究。首次通过基因组DNA及mtDNA与一含有部分atpA基因和orf H522的4.1kb探针Southern分子杂交分析及mtDNA限制性内切酶图谱分析证明,在atpA基因位点区域有4种DNA序列存在于21种细胞质雄性不育品系中。首次指出在向日葵CMS品系中即使细胞质来源相同,不育基因却有多种存在形式,并通过实验结果推测了导致细胞质雄性不育的机理。     

Variation of selfing rate and inbreeding depression among individuals and across generations within an admixed Cedrus population

We investigated the variation and short-term evolution of the selfing rate and inbreeding depression (ID) across three generations within a cedar forest that was established from admixture ca 1860. The mean selfing rate was 9.5%, ranging from 0 to 48% among 20 seed trees (estimated from paternally inherited chloroplast DNA). We computed the probability of selfing for each seed and we investigated ID by comparing selfed and outcrossed seeds within progenies, thus avoiding maternal effects. In all progenies, the germination rate was high (88–100%) and seedling mortality was low (0–12%). The germination dynamics differed significantly between selfed and outcrossed seeds within progenies in the founder gene pool but not in the following generations. This transient effect of selfing could be attributed to epistatic interactions in the original admixture. Regarding the seedling growth traits, the ID was low but significant: 8 and 6% for height and diameter growth, respectively. These rates did not vary among generations, suggesting minor gene effects. At this early stage, outcrossed seedlings outcompeted their selfed relatives, but not necessarily other selfed seedlings from other progenies. Thus, purging these slightly deleterious genes may only occur through within-family selection. Processes that maintain a high level of genetic diversity for fitness-related traits among progenies also reduce the efficiency of purging this part of the genetic load.     

Detection of androclonal variation in anther-cultured rice lines using rapds

Summary Random amplified polymorphic DNA analysis was used to determine the occurrence and extent of variation in rice (Oryza sativa L.) plants regenerated from anther culture. Androclonal variation in morphologically uniform progenies was detected using 40 10-mer oligonueleotide arbitrary primers. Among 27 plants from nine anther culture-derived lines, variation was detected in three plants from two lines by two primers, namely UBC 160 and UBC 209. Primer UBC 160 amplified a polymorphic band on one of the three progenies from DH-34, while UBC 209 detected polymorphisms on two out of three progenies from line DH-58. Apart from these, the amplification produets were monomorphic across all the regenerants from anther culture-derived plants. Out of 40 tested primers, no difference in the banding pattern was observed in three seed-derived plants. The significance of possible androclonal variation at the DNA level in rice doubled haploid breeding and genetic mapping is discussed.     

Epigenetic variability in plants: Heritability,adaptability, evolutionary significance

DNA methylation is the most stable epigenetic modification with a well studied maintenance mechanism in the mitotically dividing cell generations. The plant DNA is methylated at sites of three types, CG, CHG and CHH. The methylation mechanisms of these sites are different and involve functional activity of various DNA methyltransferases and their accessory factors, that largely define the genome locus specificity of methylation. The genome methylation pattern, DNA methylome, in plants is inheritable not only in the dividing cell generations but also to a considerable extent in generations of the whole plants. A great number of spontaneous epimutations, both natural and experimental ones, are known, that have discernible phenotypic manifestations and are stably inheritable in the plant generations as Mendelian traits. A fundamental distinction of such epimutations from classical mutations is their reversibility. The higher plants epigenome is much more flexible compared with their genome. The single-nucleotide epimutation frequency is hundredfolds higher than the mutation frequency. This variability is probably a main source of the plant phenotypic plasticity, that enables them to adapt to changing environment on the time scales too short for adaptive mutations to occur. A dramatic increase in the plant population epigenetic variability on a practically unchanged genetic context is observed when the essential environmental factors are rapidly changing. Being flexible enough for such adaptive changes, on the other hand, epigenome is stable enough for these adaptive variations to be inheritable between the plant generations. Obviously, the epigenetic variations, that enable plants to adapt to the fast changing environmental factors, serve as material for natural selection and other evolutionary processes on the respective time scales. A still another aspect of evolutionary significance is a capability of epigenetic mechanisms to induce transient bursts of genetic variability by transposon mobilization.     

Effect of in vitro culture conditions on somaclonal variation in cowpea (Vigna unguiculata Walp.) using RAPD markers

We report a high frequency regeneration protocol in cowpea (Vigna unguiculata Walp. var. C 152) via somatic embryogenesis from 10-d-old primary leaf explants. A study was conducted to examine the effect of somaclonal variations in in vitro derived cowpea plants under field conditions. The regenerated plantlets were successfully transferred to field after hardening in vitro and grown for collecting R0, R1 and R2 seeds. The seeds of R1 and R2 generations were subsequently, grown under field conditions and their various biometrical traits were compared and evaluated with non-tissue cultured cowpea plants as check. There was no detectable somaclonal variation induced in R0-R2 in any of the biometrical traits. The results indicate that the inclusion of different plant growth promoters at specified concentrations and duration in our earlier tissue culture work did not induce any detectable mutation. The RAPD analysis also shows that there is no genetic variation among R2 cowpea plants. The somatic embryogenesis protocol we report could thus be safely applied for high frequency true-to-type regeneration and transformations protocols without any somaclonal variation.     

水稻空间技术育种的研究

为探讨空间条件对水稻育种的影响,利用返回式卫星搭载水稻干种子,返地种植,考察分析了12个亲本品种后代的性状表现及遗传与变异情况。结果表明：空间条件诱变的后代性状具有多样性变异和多向性遗传,且能稳定遗传,并有超亲遗传现象,诱变后代具有变异类型多、变异频率高、特殊突变体、育种周期短等特点。为进一步开发利用空间技术育种,在研究实践的基础上,提出了程序化、规范化、可操作性强的水稻空间育种技术规范。     

Scion Control of Genotypic Differences in Mineral Salts Accumulation in Soyabean (Glycine max L. Merr.) Seed

Stem-root grafts of seedling plants were used to ascertain thatgenotypic differences in P, Mg, Mn, and B accumulation in soyabean(Glycine max L. Merr.) seeds are controlled by the scion ofthe plant. The effect of the graft per se on mineral accumulationwas negligible. These results are similar to those reportedfor Sr and Ca accumulation in soyabeans. Mechanisms which couldaccount for these observations are briefly discussed.     

The absense of a definite gene-specific effect in wheat after seed treatment with exogenous DNA

Summary To reveal gene-specific genetic transformation in wheat experiments have been performed with two inheritable marker characters, namely, the complementing genes of necrosis, ne ₁ and ne ₂, and genes of awness. The awned spikes were found after treatment of seeds of awnless wheat with the DNA isolated from both awned wheat and from awnless wheat. The awned plants conserved their changed character in subsequent generations. In the experiments with necrosis genes no single example of interaction of the ne ₁ and ne ₂ genes was found, although some non specific effects (the decrease in number of germinating plants, the increase in height of plants and the length of spikes, etc) were observed.     

Irreproducibility of the soybean pollen-tube pathway transformation procedure

The interest in developing tissue culture-independent genetic transformation methods for plants has been growth. The pollen-tube pathway transformation technique is one method; however, this method is controversial because it is difficult to duplicate and produces insufficient molecular evidence to confirm transformation. Our objective was to evaluate the robustness of the soybean pollen-tube pathway technique (Glycine max L. Merr.). Solutions of purified DNA constructs carrying abar marker gene and agus reporter gene or a gene of interest (npk1) were applied to severed styles of flowers 6–8 h after self-pollination. The experiment was repeated 3 summers in the field, in which 4 DNA constructs and 7 soybean genotypes were tested. A total of 4793 progeny seeds were harvested from 5590 individually treated soybean flowers. All seeds were germinated and screened for transformants with herbicide spray, histochemical GUS assay, and Southern blot analysis. Although 2% of progenies showed partial resistance to the herbicide, no positive plants were identified from GUS assay and Southern analysis. Our results indicate that soybean pollen-tube pathway transformation is not reproducible.     

Variations of tandem repeat, regulatory element, and promoter regions revealed by wheat-rye amphiploids.

To better understand the evolution of allopolyploids, 4 different combinations between wheat (Triticum aestivum L.) and rye (Secale cereale L.) including 12 F1 hybrids and 12 derived amphiploids were analyzed and compared with their direct parental plants by PCR analysis using 150 wheat SSR (single sequence repeat) markers and by FISH analysis using a rye-specific repetitive sequence (pSc200) as a probe. Nine SSR markers amplified rye-specific fragments whose sizes ranged from 471 bp to 1089 bp. These fragments contain regulatory elements and (or) promoters. Some of these fragments were amplified from all 24 progenies, while others were amplified from a subset of the progenies. The disappearance of rye-specific fragments from some progenies was caused by sequence elimination or DNA modification. Marker Xgwm320 amplified a new fragment (403 bp), a rye-specific tandem repeat, from some of the progenies. Twenty-eight SSR markers displayed microsatellite variation in progenies derived from 'Chinese Spring' x 'Jinzhou-heimai', but none of the 150 SSR markers displayed microsatellite variation in the progenies derived from the other three combinations. FISH signals of pSc200 were eliminated from one telomere/subtelomere of 4 chromosomes of 'Kustro' during allopolyploidization and expanded in amphiploids derived from 'Chinese Spring' x 'AR106BONE'. Thus, allopolyploidization in wheat-rye can be accompanied by rapid variation of tandem repeats, regulatory elements, and promoter regions. The alterations of repetitive sequence pSc200 indicate coordination between the constituent genomes of the newly formed amphiploids. Different genetic backgrounds of parents appear to affect genome changes during allopolyploidization.     

羊草种质基因组DNA的AFLP多态性研究

羊草是禾本科牧草之王 ,在当前我国西部生态建设和草原畜牧业发展中发挥着重要作用。用AFLP方法对2 7份我国不同地区分布的羊草 (Leymuschinensis (Trin .)Tzvel)材料进行了基因组DNA多态性分析 ,8对AFLP引物组合在 2 7个不同羊草基因型中共扩增出 5 37条带 ,产生出的DNA片段大小分布在 75bp - 5 30bp之间。其中单态性带 89条 ,占 16 .6 % ,多态性带 32 9条 ,占 6 1.3%。平均每对引物组合扩增的DNA带数为 6 6 .13,总的多态性比率为 78.84%。AFLP多态信息含量PIC值分布于 0 .0 - 0 .5之间 ,平均PIC值为 0 .2 16 ,出现的PIC最大值 (0 .5 )约占AFLP标记的 8.5 % ,说明羊草基因组DNA的多态性比较丰富。以 5 37个AFLP标记为原始数据 ,根据Nei和Li的方法对 2 7份羊草材料进行遗传变异和聚类分析的结果表明 :羊草种内有高频率的遗传变异发生 ,且与地理分布和生态环境密切相关 ;2 7份羊草不同基因型被划分为四大类群 ,不同类群相互间的遗传距离相对较大 ,在树状图中表现为较远的亲缘关系。对羊草种内遗传变异发生的原因和品种的形成进行了初步讨论。