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Somayeh NAGHILOO Masoumeh KHODAVERDI Zahra ESMAILLOU Mohammad Reza DADPOUR Paula J. RUDALL 《植物分类学报:英文版》2014,52(2):195-214
A comparative developmental study of flowers was carried out using epi-illumination light microscopy on four genera of Lamiaceae (Nepeta, Rosmarinus, Salvia, andZiziphora), representing all three subtribes of Mentheae. All species examined share unidirectional (adaxial to abaxial) sepal initiation, except Rosmarinus, which has the reverse unidirectional sequence, starting abaxially. Initiated but suppressed bracteoles were detected only in Rosmarinus. In Rosmarinus, Salvia, and Ziziphora, initiation of petals and stamens proceeds unidirectionally from the abaxial side. Floral initiation of Nepeta has bidirectional inception of petals and unidirectional stamen initiation from the adaxial side. Temporal overlap in organ initiation between petal and stamen whorls occurs in all taxa, though this feature is more prominent in Rosmarinus. Significant structural and developmental features that distinguish the four genera include: (1) polysymmetric calyx tube, highly tomentose corolla and deeply four-partitioned ovary in Nepeta; (2) monosymmetric two-lipped calyx and shallowly four-partitioned ovary in Ziziphora; and (3) suppression of adaxial stamens in Salvia and Rosmarinus. Adaxial stamens are absent from Rosmarinus, but reduced stamens remain as staminodia in Salvia. In a phylogenetic context, the late monosymmetry of Nepeta and very early monosymmetry of Rosmarinus could both be regarded as derived conditions compared with the early monosymmetry ofSalvia and Ziziphora. 相似文献
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Mark van Kleunen Anna Meier Moritz Saxenhofer Markus Fischer 《Journal of Plant Ecology》2008,1(3):173
Aims Floral traits are frequently used in traditional plant systematics because of their assumed constancy. One potential reason for the apparent constancy of flower size is that effective pollen transfer between flowers depends on the accuracy of the physical fit between the flower and pollinator. Therefore, flowers are likely to be under stronger stabilizing selection for uniform size than vegetative plant parts. Moreover, as predicted by the pollinator-mediated stabilizing selection (PMSS) hypothesis, an accurate fit between flowers and their pollinators is likely to be more important for specialized pollination systems as found in many species with bilaterally symmetric (zygomorphic) flowers than for species with radially symmetric (actinomorphic) flowers.Methods In a comparative study of 15 zygomorphic and 13 actinomorphic species in Switzerland, we tested whether variation in flower size, among and within individuals, is smaller than variation in leaf size and whether variation in flower size is smaller in zygomorphic compared to actinomorphic species.Important findings Indeed, variation in leaf length was significantly larger than variation in flower length and width. Within-individual variation in flower and leaf sizes did not differ significantly between zygomorphic and actinomorphic species. In line with the predictions of the PMSS, among-individual variation in flower length and flower width was significantly smaller for zygomorphic species than for actinomorphic species, while the two groups did not differ in leaf length variation. This suggests that plants with zygomorphic flowers have undergone stronger selection for uniform flowers than plants with actinomorphic flowers. This supports that the relative uniformity of flowers compared to vegetative structures within species, as already observed in traditional plant systematics, is, at least in part, a consequence of the requirement for effective pollination. 相似文献
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In Asterids, specific expression of CYC-like genes in the corresponding regions promotes or reduces dorsal petal growth and aborts stamen development. In Rosids, however, the reduced or enlarged dorsal petals are not accompanied by the abortion of stamens, which implies that the function of CYC-like genes in regulating petal growth and stamen development might be independently recruited. To address this, we investigated the function of the PhCYC1C gene in Primulina heterotricha Y. Dong & Y. Z. Wang on petal growth and stamen development by overexpressing it in two different transformation systems, that is, Arabidopsisbelonging to Rosids and tobacco located in Asterids. The results showed that overexpression of PhCYC1C reduced petal sizes in both tobacco and Arabidopsistransgenic plants mainly by repressing cell expansion, indicating its conserved function in determining petal growth between Asterids and Rosids. However, the fertility of both tobacco and Arabidopsis stamens was not affected at all. Given that strong expression signals of PhCYC1C are detected in both tobacco andArabidopsis stamens and CYC-like genes actually function to repress stamen development in Lamiales, we suggest that the CYC-like gene-associated regulatory network for controlling stamen development might have not established in Rosids as well as in early evolution of Asterids, but evolved as Asterids proceeded further. Our results provide valuable information on the conservation of CYC-like genes' function in controlling corolla asymmetry and the divergence of their function in determining stamen abortion in angiosperms. 相似文献
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Physiological studies on flowering time control have shown that plants integrate several environmental signals. Predictable factors, such as day length and vernalization, are regarded as 'primary', but clearly interfere with, or can even be substituted by, less predictable factors. All plant parts participate in the sensing of these interacting factors. In the case of floral induction by photoperiod, long-distance signalling is known to occur between the leaves and the shoot apical meristem (SAM) via the phloem. In the long-day plant, Sinapis alba, this long-distance signalling has also been shown to involve the root system and to include sucrose, nitrate, glutamine and cytokinins, but not gibberellins. In Arabidopsis thaliana, a number of genetic pathways controlling flowering time have been identified. Models now extend beyond 'primary' controlling factors and show an ever-increasing number of cross-talks between pathways triggered or influenced by various environmental factors and hormones (mainly gibberellins). Most of the genes involved are preferentially expressed in meristems (the SAM and the root tip), but, surprisingly, only a few are expressed preferentially or exclusively in leaves. However, long-distance signalling from leaves to SAM has been shown to occur in Arabidopsis during the induction of flowering by long days. In this review, we propose a model integrating physiological data and genes activated by the photoperiodic pathway controlling flowering time in early-flowering accessions of Arabidopsis. This model involves metabolites, hormones and gene products interacting as long- or short-distance signalling molecules. 相似文献
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Jessika Adrian Stefano Torti Franziska Turck 《植物生理学报》2009,(4):628-642
During the floral transition the shoot apical meristem changes its identity from a vegetative to an inflorescence state. This change in identity can be promoted by external signals, such as inductive photoperiod conditions or vernalization, and is accompanied by changes in expression of key developmental genes. The change in meristem identity is usually not reversible, even if the inductive signal occurs only transiently. This implies that at least some of the key genes must possess an intrinsic memory of the newly acquired expression state that ensures irreversibility of the process. In this review, we discuss different molecular scenarios that may underlie a molecular memory of gene expression. 相似文献
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Insect gut microbiota has been reported to participate in regulating host multiple biological processes including metabolism and reproduction. However, the corresponding molecular mechanisms remain largely unknown. Recent studies suggest that microRNAs (miRNAs) are involved in complex interactions between the gut microbiota and the host. Here, we used next-generation sequencing technology to characterize miRNA and mRNA expression profiles and construct the miRNA–gene regulatory network in response to gut microbiota depletion in the abdomens of female Bactrocera dorsalis. A total of 3016 differentially expressed genes (DEGs) and 18 differentially expressed miRNAs (DEMs) were identified. Based on the integrated analysis of miRNA and mRNA sequencing data, 229 negatively correlated miRNA–gene pairs were identified from the miRNA–mRNA network. Gene ontology enrichment analysis indicated that DEMs could target several genes involved in the metabolic process, oxidation–reduction process, oogenesis, and insulin signaling pathway. Finally, real-time quantitative polymerase chain reaction further verified the accuracy of RNA sequencing results. In conclusion, our study provides the profiles of miRNA and mRNA expressions under antibiotics treatment and provides an insight into the roles of miRNAs and their target genes in the interaction between the gut microbiota and its host. 相似文献
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HANS BÄNZIGER HAIQIN SUN YI-BO LUO 《Botanical journal of the Linnean Society. Linnean Society of London》2008,156(4):681-681
A new species of Gesneriaceae, Paraboea trisepala W.H.Chen & Y.M.Shui, from a karst cave in Guangxi, China is described and illustrated. The new species differs from other species of Paraboea by its three‐lobed calyx. Variation in flower and inflorescence architecture was observed under cultivation. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 681–688. 相似文献
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Background and Aims
The pollinator-mediated stabilizing selection hypothesis suggests that the specialized pollination system of zygomorphic flowers might cause stabilizing selection, reducing their flower size variation compared with actinomorphic flowers. However, the degree of ecological generalization and of dependence on pollinators varies greatly among species of both flower symmetry types and this may also affect flower size variation.Methods
Data on 43 species from two contrasting communities (one alpine and one lowland community) were used to test the relationships and interactions between flower size phenotypic variation, floral symmetry, ecological pollination generalization and species'' dependence on pollinators.Key Results
Contrary to what was expected, higher flower size variation was found in zygomorphic than in actinomorphic species in the lowland community, and no difference in flower size variation was found between symmetry types in the alpine community. The relationship between floral symmetry and flower size variation depended on ecological generalization and species'' dependence on pollinators, although the influence of ecological generalization was only detected in the alpine community. Zygomorphic species that were highly dependent on pollinators and that were ecologically specialized were less variable in flower size than ecologically generalist and selfing zygomorphic species, supporting the pollinator-mediated stabilizing selection hypothesis. However, these relationships were not found in actinomorphic species, probably because they are not dependent on any particular pollinator for efficient pollination and therefore their flower size always shows moderate levels of variation.Conclusions
The study suggests that the relationship between flower size variation and floral symmetry may be influenced by population-dependent factors, such as ecological generalization and species'' dependence on pollinators. 相似文献14.
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The hepatitis B virus (HBV) transgenic mouse (Tg) 50-4 strain is immunologically tolerant to HBV antigens. Various vaccination strategies have been attempted but failed to break the tolerance in the mouse. Although the tolerance to HBV antigen is maintained, this mouse strain develops spontaneous liver disease beginning at the age of about 3 months. We attempted to induce immune responses to HBV surface antigen (HBsAg) in the Tg by immunization with recombinant vaccinia virus expressing HBsAg (vvHBV), and observed different immunological responsiveness between 2-month-old and 5-month-old Tg. In contrast to the unbreakable tolerance reported previously, we could induce both the cytotoxic T lymphocyte (CTL) and the antibody response against HBsAg by the vvHBV immunization. The cytokine expression pattern indicated that T helper 1 type immune response was induced. However, interestingly, these immune responses were observed only in the 5-month-old Tg, but not in the 2-month-old Tg. Furthermore, CD4+ T cells from 2-month-old mice, but not those from 5-month-old mice, inhibited CTL response to HBV antigen when adoptively transferred to C57BL/6. These results suggest the possible involvement of regulatory T cell function in the HBV Tg for maintaining tolerance. This study would contribute to a better understanding of immune status of the HBV Tg as a model of human chronic hepatitis and to the search for new therapeutic targets for chronic viral infections. 相似文献
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The term merosity stands for the number of parts within whorls of floral organs, leaves, or stems. Trimery is considered to be a basic condition that arose through the cyclisation of a spiral flower. Pentamery is mostly derived from trimery by the repetitive fusion of two different whorls. Dimery is either directly derived from trimery, or through pentamery as an intermediate stage. Tetramery is linked with pentamery and should not be confused with dimery. Possible causes for a change in merosity are the reduction of the number of carpels and zygomorphy in flowers. Derivations of different merosities have important consequences for the arrangement of the androecium (the insertion of stamen whorls, their identifications, and their number). It is concluded that two main groups can be identified within the angiosperms: magnolialean and monocotyledonean taxa are mostly trimerous or dimerous; non-magnolialean dicots are mostly pentamerous or tetramerous. 相似文献
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幼苗顶端弯钩的形成是双子叶植物暗形态建成过程中的一个重要事件。它保护双子叶植物幼嫩的子叶和脆弱的顶端分生组织在幼苗出土时免受机械损伤,进而保证幼苗的出苗率和成活率。幼苗顶端弯钩的形成是由于下胚轴顶端的两个对立面之间细胞分裂和延伸的不对称所引起的。目前,关于双子叶植物幼苗顶端弯钩发育分子机制的研究已有较大进展:发现生长素在顶端弯钩内外侧组织的梯度分布是顶端弯钩两侧细胞差异生长的重要驱动力;乙烯、赤霉素和油菜素内酯促进顶端弯钩的形成和维持;茉莉酸抑制顶端弯钩的形成;而光照则促进弯钩的打开;无弯钩1 (hookless1, HLS1)、乙烯不敏感3以及EIN3 相似蛋白1 (ethylene insensitive 3 /EIN3 like 1, EIN3/EIL1)、DELLA、组成型光形态发生1(constitutive photomorphogenic 1, COP1) 和光敏色素相互作用因子(phytochrome interacting factors, PIFs) 等多种因子已被发现参与顶端弯钩的发育过程,并介导了多种激素之间的互作。本文综述了双子叶植物幼苗顶端弯钩发育过程中的重要作用因子及调控网络,并对该领域的研究前景进行了展望。 相似文献
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Expression of a cytomegalovirus IE-1-factor VIII cDNA hybrid gene in transgenic mice 总被引:1,自引:0,他引:1
Thomas R. Mikkelsen Barbara Chapman Nanni Din Jørgen Ingerslev Peter Kristensen Knud Poulsen J. Peter Hjorth 《Transgenic research》1992,1(4):164-169
A construct containing the 5′ end of the human cytomegalovirus major immediate early gene fused to the human coagulation factor
VIII cDNA was used to produce transgenic mice. Two out of five transgenic lines transcribed the construct. The expression
was consistently seen in a limited number, of tissues and was highest in muscle tissues. This is in contrast to the almost
ubiquitous activity demonstrated in earlier studies with the IE-1 enhancer/promoter. Human factor VIII protein was detected
immunochemically in muscle tissues at levels several times higher than in human plasma. 相似文献