福建薹草(莎草科)的考证

在整理和鉴定浙闽薹草属Carex植物的过程中,发现福建薹草Cares fokienensis Dunn较早发表但并未被注意。通过文献查阅、模式标本研究和野外观察,认为闽清薹草C.minqingensis Z．P.Wang、九仙山薹草C jiuxiangshanensis L.K．Dai＆Y.Z．Huang、苍绿薹草C.pallideviridis K．L．Chv（裸名）在果囊和雌花鳞片等鉴别性特征上与福建薹草并没有区别,应该处理为福建薹草的异名。     

Mycorrhizal status of the genus Carex (Cyperaceae)

The Cyperaceae have generally been considered nonmycorrhizal, although recent evidence suggests that mycotrophy may be considerably more widespread among sedges than was previously realized. This study surveyed 23 species of Carex occurring in upland and wetland habitats in northeastern Illinois. Mycorrhizal infection by arbuscular fungi was found in the roots of 16 species of Carex and appears to occur in response to many factors, both environmental and phylogenetic. While some species appear to be obligately nonmycorrhizal, edaphic influences may be responsible for infection in others. In five of the seven Carex species that were nonmycorrhizal, a novel root character, the presence of bulbous-based root hairs, was identified. The taxonomically patchy distribution of the distinctive root hair trait suggests that these structures may have evolved several times within the genus. Evidence of multiple independent origins of the root hair trait lends support to the hypothesis that root hairs represent an adaptation to nonmycotrophy. Although taxonomic position does seem to be of importance in determining the mycorrhizal dependence of sedges, the pattern may be a patchwork of both mycorrhizal clades and clades that have adapted to the nonmycorrhizal state.     

Stage-related expression of mRNAs during pollen development in lily and tobacco

Homogeneous populations of developing microspores and pollen from anthers of lily (Lilium longiflorum Thumb.) and tobacco (Nicotiana tabacum L.) show a continuous production of biomass, reaching a maximum in young pollen. The rate of RNA synthesis was 460 fg · h^–1 in young binucleate cells, 138 fg · h^–1 in late binucleate cells and 56 fg · h^–1 in microspores. The mRNA population in developing pollen can be separated into three groups. In the first group, certain types of mRNAs are present at a constant level during all stages of development. A second group is characteristic of young pollen and increases quantitatively until anthesis. A third group is seen transiently; to this belong mRNAs present only before mitosis or at a distinct cell stage after mitosis. Some of the translation products of this latter group of mRNAs showed similarities between lily and tobacco on two-dimensional gels in respect of molecular weight and isolectric point, indicating that those mRNAs and proteins play a role in the regulation of pollen development.Abbreviations cDNA copy DNA - pI isolectric pointTo whom correspondence should be addressed.     

The floral scales in Hellmuthia (Cyperaceae, Cyperoideae) and Paramapania (Cyperaceae, Mapanioideae): an ontogenetic study

BACKGROUND AND AIMS: In 1976 the monotypic genus Hellmuthia was placed in the Hypolytreae s.l., but was subsequently ascribed to the Mapanioideae, tribe Chrysitricheae, mainly because of the presence in Hellmuthia of two lateral, mapanioid-like floral scales with ciliated keels, the anatomy of the nutlet, the embryo and the inflorescence. Recently, based on cladistic analyses and supported by pollen ontogenetic evidence, Hellmuthia was transferred to a Cyperaceae, tribe Cypereae, clade mainly consisting of Ficinia and Isolepis. In this study, the floral ontogeny in Hellmuthia was investigated and compared with the floral ontogeny in Paramapania, with special attention for the floral scales. METHODS: Freshly collected inflorescences of Hellmuthia membranacea and Paramapania parvibractea were investigated using scanning electron and light microscopy. KEY RESULTS: In the conical 'spikelet' in Hellmuthia, proximal bracts occur, each axillating an axis with empty glume-like structures, or a reduced spikelet. Hence, it is a reduced partial inflorescence. In Hellmuthia, the stamen primordia originate before the primordia of the perianth-gynoecium appear. Moreover, a third adaxially positioned 'floral scale' was observed for the first time. The position and relative time of appearance of the floral scales in Hellmuthia are typical for perianth parts in Cyperoideae. The basal position of Hellmuthia within a clade of species with usually perianthless flowers, allows the presence of rudiments of a perianth in Hellmuthia to be interpreted as a primitive state. Development of the lateral 'scales' in Paramapania follows a different pattern. Therefore, it was decided that the lateral 'scales' in Paramapania are different from the lateral perianth parts in Hellmuthia. The pollen grains in Hellmuthia are cyperoid, with one polar and five lateral apertures, of which the membrane is covered with sexinous bodies. The pollen surface is granulate and perforate with microspines. CONCLUSIONS: The floral ontogeny in Hellmuthia occurs according to the general cyperoid pattern. The lateral scales in Hellmuthia are perianth parts, and they are not homologous to the lateral 'scales' in Paramapania.     

Role of microtubular cytoskeleton and callose walls in the manifestation of cytomixis in pollen mother cells of tobacco Nicotiana tabacum L.

The structure and dynamics of microtubular cytoskeleton and of callose walls in normal pollen mother cells (PMC) of tobacco N. tabacum L. and in cells with intercellular translocation of nuclear material (cytomictic) was studied in the course of the cell cycle. The microtubular cytoskeleton was established as playing no obvious role in the process of cytomixis. The elevated level of cytomictic seems to be due to disturbances of synthesis of callose walls as a result of their attenuation and perforation. Possible causes of cytomictic in tobacco PMC at the cellular level are discussed.     

The systematic significance of achene micromorphology in Carex retrorsa (Cyperaceae)

Scanning electron microscopy (SEM) was used to examine achene epidermal features of nine Carex species within sections Vesicariae and Lupulinae. Two major epidermal features are recognized in this study: the epidermal layers with one or two primary silicon bodies in each cell and the absence of any primary silicon body. Comparative data of achene morphology using SEM, and evidence compiled from previous investigations, support the placement of Carex retrorsa within section Vesicariae.     

Insights on Using Morphologic Data for Phylogenetic Analysis in Sedges (Cyperaceae)

Sedges are often viewed as difficult subjects for morphology-based phylogenetic analysis, due to several difficulties, including finding an adequate number of characters to yield well-resolved and well-supported trees, correctly assessing homology of characters and character states, and selecting appropriate outgroups for character state polarizations. The published literature holds only 11 papers with morphology-based phylogenetic analyses of sedges. This paper reviews those studies, and presents the phylogeny of two groups of sedges: (1) Carex section Deweyanae, and (2) Carex sections Careyanae, Granulares, and Griseae. This paper also presents recommendations for using morphologic data to reconstruct sedge phylogenies, based on comparisons of the trees resulting from the present study with the previous sedge studies and with similar studies of phylogeny of other groups of flowering plants. In the two groups of Carex examined, morphology does provide sufficient characters to infer well-resolved trees, with some nodes having good to strong support at levels consistent with those found in morphology-based analyses of other groups of flowering plants. The inclusion of micromorphologic and anatomic characters substantially enhances the resolving power of macromorphologic characters in sedge analyses, and increases the support for some clades.     

Disorganization of F-actin cytoskeleton precedes vacuolar disruption in pollen tubes during the in vivo self-incompatibility response in Nicotiana alata

Background and Aims The integrity of actin filaments (F-actin) is essential for pollen-tube growth. In S-RNase-based self-incompatibility (SI), incompatible pollen tubes are inhibited in the style. Consequently, research efforts have focused on the alterations of pollen F-actin cytoskeleton during the SI response. However, so far, these studies were carried out in in vitro-grown pollen tubes. This study aimed to assess the timing of in vivo changes of pollen F-actin cytoskeleton taking place after compatible and incompatible pollinations in Nicotiana alata. To our knowledge, this is the first report of the in vivo F-actin alterations occurring during pollen rejection in the S-RNase-based SI system. Methods The F-actin cytoskeleton and the vacuolar endomembrane system were fluorescently labelled in compatibly and incompatibly pollinated pistils at different times after pollination. The alterations induced by the SI reaction in pollen tubes were visualized by confocal laser scanning microscopy. Key Results Early after pollination, about 70 % of both compatible and incompatible pollen tubes showed an organized pattern of F-actin cables along the main axis of the cell. While in compatible pollinations this percentage was unchanged until pollen tubes reached the ovary, pollen tubes of incompatible pollinations underwent gradual and progressive F-actin disorganization. Colocalization of the F-actin cytoskeleton and the vacuolar endomembrane system, where S-RNases are compartmentalized, revealed that by day 6 after incompatible pollination, when the pollen-tube growth was already arrested, about 80 % of pollen tubes showed disrupted F-actin but a similar percentage had intact vacuolar compartments. Conclusions The results indicate that during the SI response in Nicotiana, disruption of the F-actin cytoskeleton precedes vacuolar membrane breakdown. Thus, incompatible pollen tubes undergo a sequential disorganization process of major subcellular structures. Results also suggest that the large pool of S-RNases released from vacuoles acts late in pollen rejection, after significant subcellular changes in incompatible pollen tubes.     

A regional approach to plant DNA barcoding provides high species resolution of sedges (Carex and Kobresia, Cyperaceae) in the Canadian Arctic Archipelago

Previous research on barcoding sedges (Carex) suggested that basic searches within a global barcoding database would probably not resolve more than 60% of the world’s some 2000 species. In this study, we take an alternative approach and explore the performance of plant DNA barcoding in the Carex lineage from an explicitly regional perspective. We characterize the utility of a subset of the proposed protein-coding and noncoding plastid barcoding regions (matK, rpoB, rpoC1, rbcL, atpF-atpH, psbK-psbI) for distinguishing species of Carex and Kobresia in the Canadian Arctic Archipelago, a clearly defined eco-geographical region representing 1% of the Earth’s landmass. Our results show that matK resolves the greatest number of species of any single-locus (95%), and when combined in a two-locus barcode, it provides 100% species resolution in all but one combination (matK + atpFH) during unweighted pair-group method with arithmetic mean averages (UPGMA) analyses. Noncoding regions were equally or more variable than matK, but as single markers they resolve substantially fewer taxa than matK alone. When difficulties with sequencing and alignment due to microstructural variation in noncoding regions are also considered, our results support other studies in suggesting that protein-coding regions are more practical as barcoding markers. Plastid DNA barcodes are an effective identification tool for species of Carex and Kobresia in the Canadian Arctic Archipelago, a region where the number of co-existing closely related species is limited. We suggest that if a regional approach to plant DNA barcoding was applied on a global scale, it could provide a solution to the generally poor species resolution seen in previous barcoding studies.     

Allozyme differentiation between the lowland Carex capitata and the alpine Carex arctogena (Cyperaceae) in Scandinavia

Within Scandinavia, Carex capitata s.l, is usually divided into two taxa: the lowland to lowalpine C. capitata s.s., and the alpine C. arctogena. The systematic status of these taxa is uncertain, reflected by their taxonomic treatment in different floras. In this study, allozymes were used to assess the degree of genetic differentiation between and within taxa. Ten populations of Carex capitata s.s. and eight of C. arctogena, from Norway and Sweden, were included in the study. Sixteen loci in eleven different enzyme systems were analysed: five were variable within or between taxa, three could be interpreted in all plants. In all, 20 different alleles were found. Four of these alleles were confined to C. capitata s.s., and two to C. arctogena. In C. capitata s.s., three loci (18%) were polymorphic, while all loci were monomorphic in C. arctogena. The number of alleles per polymorphic locus was 2.2 in C. capitata s.l. The taxa had completely different alleles at two loci {Pgi-2, Pgm-1). Nei's genetic identity was 0.86 between taxa, and ranged between 0.95 and 1 in pairwise comparisons of populations of Carex capitata s.s., while it was 1 in all comparisons between populations of C. arctogena. The distinction of C. capitata s.s. and C. arctogena as separate species agrees well with the amount of differentiation found between other congeneric species. It is suggested that the low genetic variation observed in both taxa is due to ancient founder events. The difference in genetic variability between taxa may be due to differences in immigration history: whereas C. capitata s.s. may have colonized Scandinavia from several close refugia after the last glaciation, C. arctogena may have reached Scandinavia after long-distance dispersal of a limited number of propagules.     

Floral organ growth and carbohydrate content during pollen development in Lilium

In order to understand floral sugar physiology, we correlated the growth of the organs with carbohydrate content in the flower of Lilium cv. “enchantment” during pollen development. In a previous work, we distinguished two phases in pollen ontogenesis: the anther growth phase, from the microspore mother cell until the vacuolated microspore, and the anther maturation phase, from the vacuolated microspore until anthesis. In the present work, we showed that during the growth phase, the anther underwent most of its size and dry weight growth, whereas the growth rate of nonanther organs was reduced. Anther and filament possessed the highest amounts of carbohydrates, which decreased progressively until the vacuolated microspore stage. During the maturation phase, sucrose and starch increased in all floral organs. Anther growth was completed at the Mi stage, whereas the nonanther organs began exponential growth. From these observations, we concluded that hierarchic nutritional correlations exist between the flower organs, in which the anther is the main actor: during the anther growth phase, the anther represents the highest sink strength floral organ, and mainly attracts assimilates through the filament. During the anther maturation phase, anther growth is achieved, its needs decrease, and assimilates are thus available for neighboring organs, which undergo intense growth until anthesis.     

A note on the hairy achenes of four African species of Scleria Bergius (Cyperaceae)

Surface features of hirsute achenes of four African species of Scleria have been examined by SEM. All bear unicellular, terete hairs with swollen bases. As the achenes mature and dry, the hairs collapse, except for their partly silicified bases, which appear as pit-like depressions from which the now-flattened hairs emerge. If the achene surface is not smooth the hairs are localized on the interlacunar ridges. In addition to the hairs, three of the four species examined show minute papillate protuberances from the silicified outer tangential walls of the epidermal cells. These papillae form a further ornamentation to the achenes visible only at high magnification. The fourth species entirely lacks these papillae.     

Taxonomy of the Carex flava complex (Cyperaceae) in Finland

The morphological variation in the Carex flava complex (sect. Ceratocystis ) in Finland, particularly taxa described by Alvar Palmgren as endemic to northern Europe, was studied using numerical analyses. Discriminant analyses were used to maximize the separation of the taxa. However, the separation of the taxa described by Palmgren was weak. The taxonomic treatment of the C. flava complex in Finland based on morphology, ecology, distribution and hybridization of the taxa is presented. Four species are recognized: Carex flava (the lectotype is selected here), C. lepidocarpa, C. demissa and C. viridula. C. lepidocarpa includes ssp. lepidocarpa and ssp. jemtlandica . In the polymorphic C. viridula , three taxa are recognized: var. viridula , var. bergrothii and var. pulchella . A key to the taxa is presented. The distribution of the taxa in Finland is presented, and their ecology is briefly discussed.     

Sectional limits and phylogenetic considerations in Carex section Ceratocystis (Cyperaceae)

Carex L. sectionCeratocystis Dumort. is distinct from the closely related sectionSpirostachyae (Drejer) L. Bailey. Differences in pistillate spike morphology, achene shape, and perigynium epidermis are augmented by chemical, cytological, and micromorphological evidence. Character compatibility analysis has been used to reconstruct the phylogenetic history of the sedges in sectionCeratocystis. The resulting network is shown to be robust when tested with cytological, ecological, and micromorphological data not included in its construction. Agmatoploidy has been the dominant process of chromosomal evolution in the section.     

Chromosome counts in the Carex flava complex (Cyperaceae) in Finland

Chromosome numbers from 17 Finnish populations of six taxa in the Carex flava complex were examined. Special attention was given to taxa claimed to be endemic to Fennoscandia. The meiotic counts for C. flava n = 30, C. viridula var. viridula n = 35 and var. pulchella n = 35 are in accordance with previous reports. The counts for C. jemtlandica n = 34, C. bergrothii n = 35, and C. kotilaini n = 34 are new. The hybrid C. flava × kotilaini reveals severely disturbed meiosis with many uni- and multivalents. The results are briefly discussed in relation to morphological data. Carex jemtlandica should evidently be included in C. lepidocarpa. Carex bergrothii and C. kotilaini belong to the polymorphic C. viridula , but the latter probably consitute a specific cytotype.     

华北落叶松小孢子母细胞(PMC)减数分裂和花粉的发育

采用染色体压片法系统地观察了华北落叶松Larix principis-rupprechtii小孢子母细胞(PMC)减数分裂的细胞学特征和花粉发育过程。结果表明:华北落叶松PMC减数分裂始于当年秋季,以弥散双线期的特殊状态休眠越冬,次年春天又重新恢复其后续的减数分裂过程。主要特点是在同一花药中,减数分裂不同步,且各阶段分裂速度较快,3天内全部停留在四分体阶段;二价体构型主要为两臂共发生过两次以上交换的环形二价体,少数细胞中偶见一臂发生交换的棒状二价体;其平均构型为10.62II 1.38II;中期II核分裂相既有平行式样,又有互为垂直式样,形成左右对称型和四面体型四分体,兼具单、双子叶植物四分体主要类型特点。四分体持续一周后,细胞壁开始溶解,4个小孢子分离并游离在药室中,成为独立的单核花粉。其后细胞核开始有丝分裂,最后形成由2个原叶细胞、1个管细胞、1个柄细胞和1个体细胞共5个细胞组成的成熟花粉。此外,还观察到成熟花粉当中有13.6%是由4个细胞组成的。     

Nonuniform processes of chromosome evolution in sedges (Carex: Cyperaceae)

Holocentric chromosomes-chromosomes that lack localized centromeres-occur in numerous unrelated clades of insects, flatworms, and angiosperms. Chromosome number changes in such organisms often result from fission and fusion events rather than polyploidy. In this study, I test the hypothesis that chromosome number evolves according to a uniform process in Carex section Ovales (Cyperaceae), the largest New World section of an angiosperm genus renowned for its chromosomal variability and species richness. I evaluate alternative models of chromosome evolution that allow for shifts in both stochastic and deterministic evolutionary processes and that quantify the rate of evolution and heritability/phylogenetic dependence of chromosome number. Estimates of Ornstein-Uhlenbeck model parameters and tree-scaling parameters in a generalized least squares framework demonstrate that (1) chromosome numbers evolve rapidly toward clade-specific stationary distributions that cannot be explained by constant variance (Brownian motion) evolutionary models, (2) chromosome evolution in the section is rapid and exhibits little phylogenetic inertia, and (3) explaining the phylogenetic pattern of chromosome numbers in the section entails inferring a shift in evolutionary dynamics at the root of a derived clade. The finding that chromosome evolution is not a uniform process in sedges provides a novel example of karyotypic orthoselection in an organism with holocentric chromosomes.