六个不同类型荞麦花花粉粒形态的电镜观察比较研究

对二倍体甜荞长花柱类型 (ES2 s)、二倍体甜荞短花柱类型 (ES2 S)、四倍体甜荞长花柱类型 (ES4s)、四倍体甜荞短花柱类型 (ES4S)、四倍体有翅细野荞 (GR4HI)、四倍体无翅细野荞 (GR4HO)等 6个不同荞麦类型花的花粉形态学进行了电镜观察。结果表明 :这些荞麦类型的花粉粒都是椭圆形 ,都有网状纹饰、3孔沟等特征。二倍体甜荞染色体加倍后形成的四倍体甜荞 ,相对于二倍体甜荞而言 ,花粉粒显著增大和明显变圆。无论二倍体还是四倍体甜荞 ,其长花柱型花的花粉粒都比其对应短花柱型花的花粉粒要小。尽管四倍体甜荞和四倍体细野荞在染色体数目和倍性上一样 ,但是它们在花粉粒的大小上有显著差异。四倍体细野荞有翅类型和无翅类型的花粉粒大小和形态差异不显著     

Genome differentiation in Magonoliaceae as revealed from meiotic pairing in interspecific and intergeneric hybrids

The cross compatibility within and between Yulania Spach and Michelia L.(Magnoliaceae) is relatively good and various such hybrids,obtained by conventional artificial hybridization,are available.The aim of the present study was to determine the extent of genome differentiation between the species involved in these crosses through the observation of chromosome pairing during meiosis in pollen mother cells (PMCs) of the hybrids.Chromosome pairing behavior was studied in five species (2n =38) and two interspecific hybrids of Michelia,eight species (2n =38,76 and 114) and 10 interspecific hybrids of Yulania,and three intergeneric hybrids between Michelia and Yulania.The results showed that chromosome pairing was normal with bivalent formation in diploid parental species and in interspecific hybrids.In addition to bivalents,multivalents were encountered in polyploid parental species and polyploid interspecific hybrids.In the intergeneric hybrids between a tetraploid Yulania and two diploid Michelia,19 chromosomes,most likely originating from Michelia,were unable to synapse from zygotene to metaphase I.Meiotic chromosome pairing indicated a high degree of homology between species within Michelia and Yulania and less homology between the genomes of these two genera.The differentiation of morphological characters and the distinctness of natural distribution also support the conclusion that these two genera are likely independent monophyletic groups.This suggests that the two genera were split at early evolution of Magnoliaceae and the overlapping characteristics in external morphology and internal structures of the two genera may be the result of parallel evolution or ancient common ancestry.     

SSR分子标记鉴定山葡萄和河岸葡萄种间杂种

利用SSR分子标记技术,对山葡萄和河岸葡萄种间杂交后代的真伪性进行鉴别。从12对多态性SSR引物中筛选出能扩增出父本特异性条带的7对引物,作为杂种鉴定的标记。用这7对引物对239株山葡萄和河岸葡萄的杂交后代进行鉴定。结果表明,有161株后代具有父本的特异性条带,结合田间形态学分析,确认为真杂种。另外,后代中还出现了新的条带,表明杂交后代产生了丰富的变异。因此,SSR标记可以有效地对葡萄属种间杂交后代进行真实性鉴定,可作为葡萄种质创新的有效辅助手段。     

Heterodera longicolla,n. sp. (Nematoda: Heteroderidae) from Buffalo-grass (Buchlo? dactyloides) in Kansas

Heterodera longicolla n. sp., a member of the H. goettingiana group, is described and illustrated from roots of buffalo-grass, Buchloë dactyloides (Nutt.) Engelm., in Manhattan, Kansas. This new abullate species, having second-stage larvae with only three lines in the lateral field, is most closely related to H. cyperi Golden, Rau & Cobb, 1962, but differs particularly in having a shorter stylet in larvae, males and females; in possessing only three annules on the head of larvae and males; in having a shorter tail in larvae; and by the presence on cysts of a small anus without a circum-anal pattern.     

中国科学院微生物研究所菌物标本馆馆藏菌寄生属Hypomyces标本的分类研究

对中国科学院微生物研究所菌物标本馆保存的菌寄生属标本进行了分类学方面的清理和订正,鉴定出9个种,其中大孢菌寄生H. marcrosporus、丝层菌寄生H. subiculosus和侧毛斑菌寄生H. tegillum为中国新记录种。     

The Esophageal Glands of Pratylenchus Filipjev and Apratylenchoides belli n. gen. n. sp. (Nematoda: Tylenchoidea)

The esophageal glands in the genus Pratylenchus occur in a large, single ventral lobe except for four populations in which a few specimens had the glands located dorsally. Apratylenchoides belli n. gen. n. sp. in the subfamily Radopholinae is proposed for a species having two esophageal glands in a large dorsal lobe and one gland in a smaller, shorter ventral lobe.     

Pterotylenchus cecidogenus n. gen., n. sp., a New Stem-gall Nematode Parasitizing Desmodium ovalifolium in Colombia

Pterotylenchus cecidogenus n. gen., n. sp. from stem-galls of Desmodium ovalifolium Wall. in Colombia is described and illustrated. The new genus belongs to Anguinidae and is related to Orrina Brzeski, 1980 but is unique in having large vulval flaps. P. cecidogenus has females with body 0.59-0.8 mm long, stylet 9-11 μm long, no median oesophageal bulb, a crustaformeria of 32-36 cells, a short post-vulval uterine sac, and a conical pointed tail.     

Genetic control of Eucalyptus urophylla and E. grandis resistance to canker caused by Chrysoporthe cubensis

Chrysophorte cubensis induced canker occurs in nearly all tropical and subtropical regions where eucalypts are planted, causing losses in both wood quality and volume productivity, especially so in the warmer and more humid regions of Brazil. The wide inter and intra-specific genetic variability of resistance to canker among Eucalyptus species facilitates the selection of resistant plants. In this study, we evaluated resistance to this pathogen in five Eucalyptus grandis (G) and 15 E. urophylla (U) trees, as well as in 495 individuals from 27 progenies derived from crosses between the trees. In the field, six-months-old test seedlings were inoculated with C. cubensis. Lesion length in the xylem and bark was measured eight months later. The results demonstrated that xylem lesions could preferentially be used for the selection of resistant clones. Eight trees (7 U and 1 G) were susceptible, and the remainder (8 U and 4 G) resistant. Individual narrow and broad sense heritability estimates were 17 and 81%, respectively, thereby suggesting that canker resistance is quantitative and highly dependent on dominance and epistasis.     

Interspecific transfer of P elements by crosses between Drosophila simulans and Drosophila mauritiana

Interspecific crosses were carried out between P element-transformed strains of D. simulans and a strain of D. mauritiana, a species devoid of this transposable element family. Four lines were established from hybrid females backcrossed with D. mauritiana males for four generations, and then maintained by intra-line mass mating. In situ hybridization of polytene chromosomes and southern blots showed that full-length and deleted P elements were present in all of the lines after 15 generations. We conclude that at least some of the P elements observed in two lines result from their transposition into D. mauritiana genome. Gonadal sterility, induced at 29°C in D. melanogaster by P elements also occurred with these two latter lines.     

五针白皮松在群落演替过程中的种间联结性分析

通过方差分析、χ2检验和共同出现百分率PC等的计算,对五针白皮松(Pinus squamata)分布的群落中主要树种间的种间联结性进行了定量分析。研究结果表明：2个五针白皮松分布的群落总体种间关联性为显著正相关,其中半阳坡上的群落为正相关,阴坡上的群落为显著正相关。由于半阳坡上的群落为针阔叶混交林,而阴坡上的群落为常绿阔叶林,表明五针白皮松分布的群落有从针阔叶混交林向常绿阔叶林演替的趋势。χ2检验和共同出现百分率PC的结果说明,阴坡群落的树种间有较密切的正相关,五针白皮松与其他树种总体上无关联性,表明五针白皮松是一个阳性先锋树种,它与其他物种的共同出现往往是由于随机的因素。同时,通过五针白皮松年龄结构并联系云南松(Pinus yunnanensis)与其他物种关系的分析得出结论,五针白皮松的濒危状况可能是在长期的植被演化过程中被阔叶树种排挤所造成的。     

黄瓜属不同倍性异源多倍体的形态及生理特性分析

以黄瓜属3种不同倍性异源多倍体为试验材料,比较分析它们的形态和生理特性与基因组剂量的关系,为进一步研究黄瓜属基因组剂量效应、探讨植物多倍体进化机理奠定基础。结果表明:(1)黄瓜属异源四倍体与种间杂种F1相比,其叶片厚度、主蔓直径等性状随基因组剂量的增加而增大,而果实大小、主蔓节间长以及果瘤果刺的大小随基因组剂量的增加而减小。(2)在异源三倍体中,叶片厚度和主蔓直径等表型性状也表现出一定的基因组剂量效应。(3)基因组剂量的变化会引起黄瓜属异源多倍体中叶绿素含量、POD活性以及IAAi、PA和ZR等内源激素的变化。     

Genetic diversity in epichloid endophytes of Hordelymus europaeus suggests repeated host jumps and interspecific hybridizations

Epichloid fungal endophytes (Epichloë and Neotyphodium spp.) are excellent model systems for studying speciation processes because of their variable life history traits that are linked to host grass fitness. Presumed jumps to new hosts and subsequent somatic hybridizations appear to be common among epichloid endophytes resulting in increased genetic variation upon which selection can act and speciation be initiated. In this study, we explored the endophyte diversity of a rare European native woodland grass species, Hordelymus europaeus, along a latitudinal transect covering the entire distribution range of H. europaeus. From 28 populations in six countries, isolates were sampled and molecularly characterized. Based on the sequences of tubB and tefA, six distinct epichloid taxa (interspecific hybrid or cryptic haploid species) were found, of which four were novel and two have been previously reported from this host. Of the novel endophytes, two were presumed to be interspecific hybrids and two of nonhybrid origin. While previously known endophytes of H. europaeus are seed‐born and strictly asexual, one of the novel nonhybrid endophytes found in the glacial refugium of the Apennine peninsula reproduced sexually in cultured plants. This is the first case of a seed‐borne, but sexually reproducing endophyte of this host. We discuss the origin, and possible ancestral species, of the six epichloid taxa using phylogenetic analyses. Repeated host jumps and somatic hybridizations characterize the diversity of the endophytes. To date, no other grass species is known to host a larger diversity of endophytes than H. europaeus.     

Heterodera canadensis n. sp. (Nematoda: Heteroderidae) from Spike-Rush (Eleocharis acicularis (L.) R. &S.) in Quebec,Canada

Heterodera canadensis n. sp. is described and illustrated from the roots of spike-rush, Eleocharis acicularis (L.) R. &S., in Deschenes, Quebec. This new abullate species is related to Heterodera graminophila Golden and Birchfield, 1972, but differs significantly in cyst shape, cone top structures, body length of the second-stage larva (520-600 μm, vs. 380-400 for H. graminophila) and tail length (110-120 μm, vs. 57-67 for H. graminophila). A taxonomic key based on cyst and second-stage larva characters is provided for identification of the fifteen species in the Heterodera goettingiana group.     

Hybridisation in the Littorina saxatilis species complex (Prosobranchia : Mollusca)

This paper details attempts to breed members of the L. saxatilis species complex in the laboratory and to construct interspecific hybrids between them. Success in reciprocal crosses between animals from the type localities of the species of Littorina saxatilis (Olivi) and Littorina rudis (Maton) indicates that these two taxa are synonymous. Six of the twelve possible reciprocal hybridisation crosses between the four species (L. saxatilis, L. arcana Hannaford Ellis, L. nigrolineata Gray and L. neglecta Bean) have been attempted, with only one proving successful, that between male L. saxatilis and female L. arcana. This hybrid cross produces viable offspring, although at a lower frequency than either of the parental crosses in the laboratory, while the reciprocal cross has, as yet, proved unsuccessful. Limited work on the F1 hybrids shows them to be inter-fertile and also capable of backcrossing with male L. saxatilis, but not with female L. saxatilis or L. arcana. Details are also given of attempts to find natural hybrids in sympatric populations of the species of the complex, using gel electrophoresis.     

部分菊属植物及其种间杂种减数分裂异常现象观察

对不同倍数性菊属植物及其部分种间杂种的减数分裂异常现象进行观察统计,并分析其形成机制以及在菊属系统演化中的作用。结果表明,菊属减数分裂异常现象包括分裂不同步、二价体提前解离、二价体互锁、染色体桥、落后染色体等。减数分裂不同步现象普遍存在于菊属植物减数分裂过程。二倍体的菊花脑、甘菊、异色菊的部分二价体在终变期提前解离为单价体。菊花脑及其部分杂种中观察到了互锁二价体。四倍体菊花脑、南京野菊、‘黄英’、‘滁菊’在AI和AII都出现了染色体桥,毛华菊有1.5%的PMC在AI出现染色体桥。四倍体菊花脑AI、AII期出现落后染色体的频率分别为10.6%和7.3%;毛华菊AI期出现落后染色体的频率为4.4%;栽培菊‘黄英’和‘滁菊’在AI、AII期出现落后染色体的频率高于毛华菊。杂种出现染色体桥及落后染色体的频率普遍高于亲本。倒位以及由其引起的各种染色体结构变异可能在菊属系统演化过程中起着重要作用。     

山西五鹿山白皮松群落乔木层的种间关联性分析

根据2×2联列表,运用方差分析、χ2检验、AC指数、Ochiai指数等技术,对山西五鹿山白皮松群落50个样方内的26种乔木的种间总体联结关系以及各种对间关联显著性和关联系数进行分析与测定。结果表明:该地区26种乔木的总体联结关系以正关联为主,表明白皮松林与其外环境是相适应的;种对间以正、负关联两种形式存在,成对物种之间正负关联的出现,是该群落内环境的表现,也是由群落内环境异质性所致。     

甘肃省小陇山濒危珍稀植物白皮松群落种间关联

通过野外调查,选取小陇山白皮松群落50个样方的20个常见物种,运用多物种方差比值(VR),χ2检验,OI、DI、JI指数,AC、PC值以及Pearson相关系数和Spearman秩相关系数对其进行了种间关联分析。VR分析表明,白皮松林主要组成成分间的关系以正关联为主,说明白皮松群落的性质与其生存环境特征是一致的,白皮松林适应群落外环境;20个常见种种对关系表现出了不同的性质,是群落内环境的表现,也是由群落内环境异质性所致;综合植物的生态特征,划分出3个生态种组,发现白皮松群落的高负关联性是由林下喜阴灌木引起的,而群落较高的独立性则是由林缘植物引起的。种间关联的研究可以反映出由物种生态特征所形成的有机联系,研究结果对白皮松群落的保护与恢复有一定的指导意义。