水生维管植物克隆繁殖方式的多样性

克隆繁殖是植物界的一种重要的繁殖方式 ,具有很大的多样性 ,特别是水生维管植物更是如此。通过对水生维管植物克隆繁殖方式的进行深入分析 ,不仅揭示了克隆繁殖在水生维管植物适应环境中的意义 ,而且也阐明了克隆繁殖方式作为水生维管植物的生存对策之一 ,在水生维管植物的生态和演化以及进化过程中的重要作用。     

Cost of reproduction in the perennial herb Asphodelus albus (Liliaceae)

The cost of reproduction has been studied in two populations of the polycarpic herb Asphodelus albus under natural conditions The percentage of plants with flowers was determined in four sites and varied markedly among them The occurrence of reproduction was size-dependent, increasing flowering probability with plant size The cost of reproduction was assessed in terms of modular growth in reproductive plants relative to modular growth in vegetative ones I compared the modular growth of vegetative and reproductive plants considering two different densities m each of two populations Neither incidence of flowering nor modular growth were affected by density Flowering plants exhibited a withinramet demographic cost (in terms of modular growth) relative to non-flowering ramets in one population but not in the other This cost was greater in larger plants These results were concordant with the occurrence of flowering at both sites Both populations exhibited size-dependent patterns of allocation to reproduction, but no significant relationships were found between allocation to reproduction and cost of reproduction The data presented demonstrate differences in the cost of reproduction within a species This cost might determine whether a plant begins the reproduction, but probably have no effect on the reproductive allocation since the weight of the reproductive structures was not related to modular growth     

薇甘菊不同生长方式下的繁殖特征比较

利用实验生态学方法, 对攀缘生长与伏地生长的薇甘菊(Mikania micrantha)的形态特征、生物量分配和繁殖特征进行了比较研究。结果表明: 在潮湿生境条件下, 攀缘生长的植株与伏地生长的植株相比对主茎的生物量投资较大, 而对分枝茎的生物量投资则相对较小; 但在干旱生境条件下, 攀缘生长的植株对主茎和分枝茎的生物量投资均较伏地生长的植株小。在潮湿与干旱生境中, 攀缘植株的繁殖投资分别为0.429 g·g^–1和0.342 g·g^–1, 显著高于相同生境中的伏地植株。在薇甘菊种群的补充与更新过程中, 攀缘生长的植株以有性生殖占主导地位, 在潮湿与干旱生境中产生的个体分别占种群数量的84.7%和62.6%; 伏地生长的植株则主要以无性(克隆)繁殖为主, 在潮湿与干旱生境中有性生殖产生的个体仅占种群数量的40.4%和35.9%。生长方式与土壤水分二因子互作效应对薇甘菊的生物量分配和繁殖指标影响均达到显著水平(P<0.05)。通过研究得出以下结论: 不同生长方式的薇甘菊对环境条件具有不同的生长与繁殖适应对策。     

丛枝菌根真菌对植物繁殖的影响研究进展

丛枝菌根真菌(arbuscular mycorrhizal fungi, AMF)与宿主植物所形成的互惠共生体系是生态系统中广泛分布的共生体系代表类型之一。AMF除能够促进宿主植物生长发育外,也可以对宿主植物的繁殖过程产生多方面影响。研究宿主植物在AMF共生状态下繁殖策略的变化规律,对于深入理解植物繁殖适合度的变化具有重要理论意义。该文综述了AMF对宿主植物繁殖影响的相关研究,包括AMF的侵染对宿主植物繁殖分配、花部特征、虫媒传粉和花期的影响。目前已有研究发现某些AMF能够促进宿主植物增加繁殖资源投入,提高花朵产生的数量或花冠直径,同时增加花粉数量和花蜜量来影响访花昆虫的行为,以及造成开花提前及花期延长,但其作用的具体机制尚不明确,且因宿主植物的差异,并未有完全统一的结论。然而,由于AMF与植物共生的普遍性,其在植物繁殖过程中发挥的重要作用不可忽略。今后除了在以上各方面开展更深入的研究外,还需在AMF对宿主植物繁殖性状的影响机制、AMF共生条件下植物有性繁殖过程中雌雄功能的资源分配,以及对无性繁殖和后代适应性的影响等方面进行更深入的研究。     

Somatic and demographic costs under different temperature regimes in the late-flowering alpine perennial herb Saxifraga stellaris (Saxifragaceae)

If reproduction involves costs, preventing reproduction one year should result in increased growth and/or reproduction the next year. Costs of reproduction in the late-flowering perennial alpine herb Saxifraga stellaris were studied in an experimental field study. To determine whether cost of reproduction differed between two contrasting temperature regimes, I examined plants in Open Top Chambers (OTCs) and control plots. One year before measurements all flower buds on the experiment plants were removed. There was no impact of the flower bud removal or the interaction between flower removal and temperature on prefloration time or seed maturation time. However, cost of reproduction influenced growth (somatic cost), vegetative propagation, flowering frequency, number of stem per ramet, number of fruits, and seed mass (demographic cost). However, significant interaction effects of flower removal and temperature on growth and fruit production revealed that the cost of reproduction differed between the two temperature regimes. The warmed plants showed reduced cost of reproduction compared to plants growing under natural temperature.     

Demographic consequences of greater clonal than sexual reproduction in Dicentra canadensis

Clonality is a widespread life history trait in flowering plants that may be essential for population persistence, especially in environments where sexual reproduction is unpredictable. Frequent clonal reproduction, however, could hinder sexual reproduction by spatially aggregating ramets that compete with seedlings and reduce inter‐genet pollination. Nevertheless, the role of clonality in relation to variable sexual reproduction in population dynamics is often overlooked. We combined population matrix models and pollination experiments to compare the demographic contributions of clonal and sexual reproduction in three Dicentra canadensis populations, one in a well‐forested landscape and two in isolated forest remnants. We constructed stage‐based transition matrices from 3 years of census data to evaluate annual population growth rates, λ. We used loop analysis to evaluate the relative contribution of different reproductive pathways to λ. Despite strong temporal and spatial variation in seed set, populations generally showed stable growth rates. Although we detected some pollen limitation of seed set, manipulative pollination treatments did not affect population growth rates. Clonal reproduction contributed significantly more than sexual reproduction to population growth in the forest remnants. Only at the well‐forested site did sexual reproduction contribute as much as clonal reproduction to population growth. Flowering plants were more likely to transition to a smaller size class with reduced reproductive potential in the following year than similarly sized nonflowering plants, suggesting energy trade‐offs between sexual and clonal reproduction at the individual level. Seed production had negligible effects on growth and tuber production of individual plants. Our results demonstrate that clonal reproduction is vital for population persistence in a system where sexual reproduction is unpredictable. The bias toward clonality may be driven by low fitness returns for resource investment in sexual reproduction at the individual level. However, chronic failure in sexual reproduction may exacerbate the imbalance between sexual and clonal reproduction and eventually lead to irreversible loss of sex in the population.     

Survival costs of reproduction in a short-lived perennial plant: Live hard, die young

According to life-history theory, reproductive investments involve costs in terms of growth, future fecundity, and/or survival. However, studies to date have often failed to detect costs of reproduction, with survival costs among the less documented. We investigated the cost of reproduction in Helianthemum squamatum (Cistaceae), a short-lived perennial of semiarid Mediterranean environments. After experimental flower removal, we evaluated next season's growth, reproduction, and survival of the plants. We also monitored an indicator of plant physiological status (F(v)/F(m)) and leaf nutrient concentration at key phenological stages during reproduction. Survival rate in deblossomed plants was significantly higher than in control plants. As far as we know, this is the first experimental evidence of a survival cost of reproduction in a perennial plant. In contrast, no cost to growth or reproduction was found during the next season, and no significant differences in F(v)/F(m) or leaf nutrients were found between control and deblossomed plants. Helianthemum squamatum's success in semiarid Mediterranean ecosystems seems to rely on a persistent seed bank, combined with a sustained high reproductive output at the expense of survival. We conclude that this strategy might be more common than previously thought among short-lived shrubby plants growing in stressful Mediterranean areas.     

Asexual reproduction, habitat colonization and habitat maintenance in bryophytes

Asexual reproduction s. l. is widespread in plants and also a basic reproductive mechanism in bryophytes. Today, three types of asexual reproduction are recognized: (1) the asexual reproduction s. str. by regeneration from ± specialized caducous organs (leaves, leaf apices, shoots, branches, bulbils) and by production of specialized propagules (gemmae, protonemal brood cells, tubers), (2) fragmentation of plants, resp. part of plants into ± unspecialized fragments, and (3) clonal reproduction (cloning). The latter occurs in bryophytes by protonema decay, by disintegration of modules, resp. formation of ramets (dividuals, “daughter plants”) that leads to self-cloning or forced-cloning of parts of the gametophyte (shoots, stoloniferous and rhizomatous axes, rhizoid wicks, basiscopic innovation plants). Clonal reproduction (cloning), in former time scarcely noted, gained great interest within the last decade mainly in vascular plants showing clonal growth. This reproduction mechanism is thought to be a keystone factor for asexual reproduction, habitat colonization and habitat maintenance. Species which reproduce clonally are able to colonize and maintain habitats in an effective way by the so-called “consequent vegetative multiplication”. The review presents an overview of the current state of knowledge of asexual reproduction types in bryophytes, with a focus on fragmentation and clonal reproduction (cloning), the mechanisms of habitat colonization and habitat maintenance, which all are of important significance in the dynamic processes of development of bryophyte populations.     

Reproduction pathway analysis of several Hypericum perforatum L. somaclonal families

Flow cytometry seed screen of mature seeds originating from several in vitro regenerated Hypericum perforatum L. somaclones and their seed progenies were used to screen the ways of reproduction of 4 subsequent generations of several somaclonal families and to search for the relation between the ploidy and prevalent mode of reproduction. The prevalent reproduction pathway of diploid plants was sexual reproduction. Seed samples of plants with higher ploidy levels showed an extensive variation in the mode of reproduction: BII and BIII hybrid formation and/or aposporous pseudogamy including parthenogenetic development of a reduced embryo sac.     

外来有害植物种群扩散的综合测定方法

在外来有害植物试点调查的基础上,结合外来有害植物的特点,介绍了外来有害植物种群测定的样地选择和设置方法.对外来有害植物入侵生境条件、有性繁殖能力、无性繁殖能力及入侵现状评价、种群扩散测定的内容和计算方法进行了概括.并根据以上资料,计算了外来有害植物综合分析指数,分析外来有害植物入侵现状以及发展趋势,为综合治理外来有害植物提供参考资料.     

外来有害植物种群扩散的综合测定方法

在外来有害植物试点调查的基础上, 结合外来有害植物的特点, 介绍了外来有害植物种群测定的样地选择和设置方法。对外来有害植物入侵生境条件、有性繁殖能力、无性繁殖能力及入侵现状评价、种群扩散测定的内容和计算方法进行了概括。并根据以上资料, 计算了外来有害植物综合分析指数, 分析外来有害植物入侵现状以及发展趋势, 为综合治理外来有害植物提供参考资料。     

The effect of plant size on vegetative reproduction in a pseudo-annual

The relationship between plant size and vegetative reproduction in clonal plants appears complex because vegetative expansion, growth, and reproduction are not clearly separable in such plants. In pseudo-annuals, which are clonal plants surviving the winter only as seeds and hibernacles produced by the rhizome apices, vegetative growth and reproduction are clearly separate processes so that the relationship between vegetative reproduction and plant size can be studied. We used the pseudo-annual Helianthus x laetiflorus Pers. to study the relationship between plant size and total rhizome biomass, rhizome (hibernacle) biomass, and number of hibernacles. We manipulated resource acquisition of the plants by reducing leaf area (leaf-clipping) and by fertilization, thus affecting plant size. Furthermore, we studied the success of thin and thick hibernacles in terms of future growth and reproduction in a separate experiment. The results showed that vegetative reproduction was positively related to plant size. The ratio between the number of hibernacles and mean hibernacle weight was affected by plant size in such a way that in small plants both number of hibernacles and mean hibernacle weight were reduced to the same extent as compared to those in large plants.However, the size distributions of plants of the next generation growing from thin and thick hibernacles did not differ. It remains unclear therefore why this pseudo-annual species produces thick hibernacles at all.     

植物富含半胱氨酸蛋白的研究进展

富含半胱氨酸蛋白（cystein-rich proteins,CRPs）是动植物中广泛存在的一类小的分泌性蛋白,具有广泛的生物学功能,如防御、蛋白酶抑制、重金属解毒等。人们在深入研究植物CRPs防御功能的同时,发现CRPs还参与调节植物的生长、发育、生殖等。本文综述了植物CRPs的分类、结构及其在植物生长发育、生殖信号转导等方面的研究进展。     

植物富含半胱氨酸蛋白的研究进展

富含半胱氨酸蛋白(cystein-rich proteins,CRPs)是动植物中广泛存在的一类小的分泌性蛋白,具有广泛的生物学功能,如防御、蛋白酶抑制、重金属解毒等。人们在深入研究植物CRPs防御功能的同时,发现CRPs还参与调节植物的生长、发育、生殖等。本文综述了植物CRPs的分类、结构及其在植物生长发育、生殖信号转导等方面的研究进展。     

Effects of supplementary feeding on growth and reproduction of three carnivorous plant species in a subarctic environment

1 The effect of supplementary feeding on growth and reproduction of three carnivorous plants species was investigated over a 6‐year period. Pinguicula alpina , P. villosa and P. vulgaris populations growing at two altitudes in a subarctic environment were fed with fruit flies ( Drosophila melanogaster ).
2 Fed plants increased in size relative to control plants during the first years. Subsequently a stable size difference between feeding levels was established. The weight of the over‐wintering part was higher in fed plants than in control plants.
3 The flowering frequency (i.e. proportion of plants in a population carrying flowers) was also higher in the fed plants. The proportion of flowering plants increased in the feeding treatment compared to control plants during more‐or‐less the whole experimental feeding period (5–6 years). Seed production also increased slowly in response to feeding.
4 No feeding effect on nitrogen and phosphorus concentrations in seeds and over‐wintering parts was found.
5 In most characteristics the high‐altitude populations were less responsive than populations growing at low altitude. In the high‐altitude population reproduction failed repeatedly, suggesting that seed output may be more dependent on abiotic factors than on resource availability in cold environments.
6 Pinguicula villosa and P. vulgaris used the new resources the same summer for increased leaf rosette growth and current reproduction, showing these species to be income breeders, while the third species ( P. alpina ) allocated a larger proportion to storage and future reproduction, characteristic of a capital breeder.     

Resource allocation to sexual and vegetative reproduction in a forest herbSyneilesis palmata (Compositae)

The balance between sexual and vegetative reproduction inSyneilesis palmata was examined in relation to environmental conditions and the amount of reproductive resources, which is defined here as the total quantity of dry matter invested in both modes of reproduction. The allocation balance was measured for individual plants of two populations, with different densities in an open habitat, for 2 years, and those of two other populations, under different light intensities in a plantation forest (forest floor and edge), for 3 years. Relative allocation to sexual reproduction decreased with increasing reproductive resources in all populations except for the forest edge, which showed a constant allocation balance. The high density population showed lower relative allocation to sexual reproduction than the low density population, irrespective of the amount of reproductive resources. However the between-year comparison of the high density population suggested that under extremely high density, plants with a small amount of reproductive resources enhanced sexual reproduction, while plants with a large amount of reproductive resources reproduced vegetatively. On the forest floor, plants with small amounts of reproductive resources had higher relative allocation to sexual reproduction than the forest edge population, while plants with large amounts of reproductive resources had a somewhat lower one. The adaptive significance of such allocation patterns are discussed, based on qualitative data on the characteristics of both types of offspring.     

Adaptive genetic differentiation in life-history traits between populations of <Emphasis Type="Italic">Mimulus guttatus</Emphasis> with annual and perennial life-cycles

The optimal allocation to sexual and vegetative reproduction as well as the optimal values of other life-history characteristics such as phenology, growth and mating system are likely to depend on the life-cycle of the organism. I tested whether plants of Mimulus guttatus originating from temporarily wet populations where the species has an enforced annual life-cycle have higher allocation to sexual reproduction, lower allocation to vegetative reproduction, more rapid phenology, faster growth, and floral traits associated with a self-fertilizing mating system than plants from permanently wet populations where the species has a perennial life-cycle. I grew a total of 1377 plants originating from three populations with an annual life-cycle and 11 populations with a perennial life-cycle in a greenhouse under permanently and temporarily wet conditions. Plants of M. guttatus in permanently wet conditions had significantly more vegetative reproduction and tended to have a faster growth than plants in the temporarily wet conditions, indicating plasticity in these life-history traits. Plants from populations with an annual life-cycle invested significantly more in sexual reproduction and significantly less in vegetative reproduction than the ones from populations with a perennial life-cycle. Moreover, this study showed that plants originating from populations with an annual life-cycle have a significantly faster development and floral traits associated with autonomous self-fertilization. In conclusion, this study suggests that there has been adaptive evolution of life history traits of M. guttatus in response to natural watering conditions that determine the life span of the species.     

Pollination ecology of Christmas Bells (Blandfordia nobilis Sm.): Effects of adding artificial nectar on pollen removal and seed-set

Addition of artificial nectar to Blandfordia nobilis plants increased fruit set in plants treated in December but had no apparent effect on either fruit set for plants treated in January or the amount of pollen removed per plant for either the December or January plants. Increased nectar production would therefore have conferred no apparent reproductive advantage to a plant flowering in January and would have been advantageous to a December flowering plant only in terms of reproduction as a female, and not in terms of male reproduction.     

An experimental demonstration of the cost of sex and a potential resource limitation on reproduction in the moss Pterygoneurum (Pottiaceae)

The cost of sexual reproduction is incurred when the current reproductive episode contributes to a a decline in future plant performance. To test the hypotheses that a trade-off exists between current sexual reproduction and subsequent clonal regeneration and that resources limit reproduction and regeneration, plants of the widespread moss Pterygoneurum ovatum were subjected to induced sporophytic abortion, upper leaf removal, and nutrient amendment treatments. Sexually reproducing plants were slower or less likely to produce regenerative structures (protonemata or shoots) and produced fewer regenerative tissue areas or structures. The ability and the timeline to reproduce sexually and regenerate clonally were unaffected by an inorganic nutrient amendment. However, when leaves subtending the sporophyte were removed, the sporophytes were less likely to mature, tended to take a longer time to mature, and were smaller compared to sporophytes from shoots with a full complement of upper leaves. Our findings indicate that plants investing in sexual reproduction suffer a cost of decreased clonal regeneration and indicate that sporophyte maturation is resource-limited, with upper leaves contributing to the nutrition of the sporophyte. This study represents only the second explicit experimental demonstration of a trade-off between sexual and asexual reproduction in bryophytes.     

入侵植物的繁殖策略以及对本土植物繁殖的影响

理解入侵生物的繁殖策略是阐明生物入侵机制的一个重要方面。入侵植物常表现出一些共同的繁殖特征, 如以两性花为主的性系统、自动自交为主的繁育系统或不依赖传粉媒介的无融合生殖和无性繁殖以及高生殖投资的资源配置策略等。成功入侵的外来植物通过影响本土的传粉者, 在种群和群落水平上影响本土植物的有性繁殖, 甚至促使某些本土植物在繁殖对策和表型性状上发生快速转变。目前, 入侵植物繁殖策略及其生态效应的研究多侧重于入侵种的快速演化, 而有关外来植物与本土植物间的相互影响及其可能存在的协同适应研究还较为缺乏。探讨本土植物在外来种入侵压力下的繁殖对策和响应机制, 将丰富人们对物种间竞争、共存及群落构建等机制的深入了解。从繁殖和适应的角度探求入侵植物与本土植物之间的复杂关系, 将有助于解析生物入侵的机制及人类干扰下的物种演化规律, 也为预测和防控入侵植物提供科学依据。