Clonal Transgenerational Effects Transmit for Multiple Generations in a Floating Plant

Environmental conditions of a parent plant can influence the performance of their clonal offspring,and such clonal transgenerational effects may help offspring adapt to different environments.However,it is still unclear how many vegetative generations clonal transgenerational effects can transmit for and whether it depends on the environmental conditions of the offspring.We grew the ancestor ramets of the floating clonal plant Spirodela polyrhiza under a high and a low nutrient level and obtained the so-called 1^(st)-generation offspring ramets of two types(from these two environments).Then we grew the 1^(st)-generation offspring ramets of each type under the high and the low nutrient level and obtained the so-called 2^(nd)-generation offspring ramets of four types.We repeated this procedure for another five times and analyzed clonal transgenerational effects on growth,morphology and biomass allocation of the 1^(st)-to the 6^(th)-generation offspring ramets.We found positive,negative or neutral(no)transgenerational effects of the ancestor nutrient condition on the offspring of S.polyrhiza,depending on the number of vegetative generations,the nutrient condition of the offspring environment and the traits considered.We observed significant clonal transgenerational effects on the 6^(th)-generation offspring;such effects occurred for all three types of traits(growth,morphology and allocation),but varied depending on the nutrient condition of the offspring environment and the traits considered.Our results suggest that clonal transgenerational effects can transmit for multiple vegetative generations and such impacts can vary depending on the environmental conditions of offspring.

Molecular Genetic Variation in a Clonal Plant Population of Leymus chinensis （Trin.） Tzvel.

Randomly amplified polymorphic DNA (RAPD) analysis was used to investigate the genetic variation among populations, between populations, and within populations, relationships between genetic distance and geographic distance, and the molecular variation and population size. The effects of geographic and genetic distances, as well as of genetic differentiation and population size, on genetic variations of Leymus chinensis (Trin.) Tzvel. are discussed. The present study showed that there was significant RAPD variation between the Baicheng region population and the Daqing region population, with a molecular variance of 6.35% (P ＜ 0.04), and for differentiation among area populations of the Daqing region, with a molecular variance of 8.78% (P ＜ 0.002). A 21.06% RAPD variation among all 16 populations among two regions was found (P ＜ 0.001), as well as 72.59% variation within populations (P ＜ 0.001). Molecular variation within populations was significantly different among 16 populations.

Importance of starting points in heterogeneous environments: interactions between two clonal plants with contrasting spatial architectures

在异质性环境中,植物能够通过将更多的生物量投资到高资源斑块而获利。因此,相对于高资源斑块的初始生长位置可能会对植物的生长和竞争能力产生影响,且这种影响可能与植物的构型有关。然而,以往有关土壤异质性对植物生长和竞争影响的研究都忽略了植物初始生长位置的潜在效应。在本研究中,我们把密集型克隆植物翼果苔草(Carex neurocarpa)和游击型克隆植物扁秆荆三棱(Bolboschoenus planiculmis)分别单独种植(不存在竞争)或者混合种植(存在竞争)在由高营养斑块和低营养斑块组成的异质性环境中。在不存在竞争处理时,每种植物的一个分株被分别单独种植于高营养或者低营养斑块中;在存在竞争处理时,目标种的一个分株被种植于高营养斑块中,而竞争种被种植在这个高营养斑块中或者邻近的低营养斑块中,或目标种的一个分株被种植于低营养斑块中,而竞争种被种植在这个低营养斑块中或者邻近的高营养斑块中。结果表明,在不存在竞争时,初始生长位置处于高营养斑块的翼果苔草的生物量和分株数均显著高于初始位置处于低营养斑块的翼果苔草,但在存在竞争时,却未发现这种差异。因此,初始位置处于高营养斑块的翼果苔草受到的竞争强度要显著高于初始位置处于低营养斑块的翼果苔草,而且这种效应与其竞争者的初始生长位置无关。相反的,扁秆荆三棱的初始生长位置对其生长和竞争的响应没有影响。因此,在异质性环境中,克隆植物的初始生长位置能够影响其生长和相对竞争能力,并且这些效应可能取决于植物的克隆构型。

Resource Sharing by the Different Clonal White Clover Plant(Trifolium repens L.)

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植物克隆整合生态效应及潜在应用

克隆植物因特殊的克隆整合和空间拓展特性,在异质生境下展示出较高的生态适应性及适合度,这是其广泛存在于各类生态系统的一个重要原因。目前对克隆整合在个体或种群水平的生态学效应已有较深认识,而对群落及生态系统的影响及作用机制则明显关注不足。前期研究表明,克隆整合对土壤理化性质、根际微生物及个体竞争力均有显著影响,从而有利于克隆植物的成功入侵、生境修复及植被重建等。对群落及生态系统水平的克隆整合生态学效应的研究进行归纳和总结,分析了克隆整合对植物群落结构和生产力、根际微生物和土壤动物、生态系统碳固持、养分循环等的影响;阐释了克隆整合及空间拓展特性对退化生态系统的修复及作用机制,并指出今后克隆整合的研究应同时考虑微观(根际过程)和宏观(群落及生态系统)层次的效应以及短期与长期的效应。可将克隆整合与植物-土壤反馈等其他生态过程相联系,综合探究克隆整合的生态学意义。

Role of Clonal Integration among Different Environmental Conditions (A Review)

Most of the ecosystems are dominated by clonal species. The most unique feature of clonal plants is their capability for clonal integration (translocation of vital resources among connected ramets), implying that integration may play an essential role in their success. However, a general effect of clonal integration on plant performance is lacking. We conducted a text review on the effects of clonal integration on different habitats and species. Overall, clonal integration increased performance of clonal plants in different habitats. However clonal integration has also some limitations under stressful environments. Benefits of clonal integration may lack somehow when environmental stress increases. But connected ramets placed in unfavorable patches benefited more from integration compared to severed ramet placed in nutrient rich patches. Climate change and temperature increase have positive effects on biomass of clonal species.

Study on Clonal Growth Pattern of Sabina vulgaris in Mu Us Sandland

The clonal growth pattern of Sabina vulgaris, a coniferous clonal plant in Mu Us sandland, Inner Mongolia Autonomous Region was surveyed. The results showed that with the stolon extending, internode length and branching angle decreased, the branching intensity increased gradually within the 3 m range from the edge of the shrub to its center along the stolon. Internode length, branching intensity and branching angle were 5.9 cm, 4.4 and 55.3°in the shrub, and 1.6 cm, 13.7 and 38.3°at the edge of the shrub, respectively. The clonal architecture exhibited plasticity. The internode length, branching intensity and ramet length changed with an exponential model with extention of the stolon. The stolon of S. vulgaris was monopodial branching, and each ramet should possess more than 3 adventitious roots. Ramets could take on the phenomenon of 搒elf-thinning?with clonal growth. There was a prior grade in allocation of the nutrients gained from heterogeneous space. The clonal architecture of S. vulgaris was the 搈ixed?type.

Soil Moisture Rather than Soil Nutrient Regulates the Belowground Bud Bank of Rhizomatous Species Psammochloa villosa in Arid Sand Dunes

In arid and semi-arid sand dune ecosystems,belowground bud bank plays an important role in population regeneration and vegetation restoration.However,the responses of belowground bud bank size and composition to sand burial and its induced changes in soil environmental factors have been rarely studied.In arid sand dunes of Northwestern China,we investigated belowground bud bank size and composition of the typical rhizomatous psammophyte Psammochloa villosa as well as three key soil environmental factors(soil moisture,total carbon and total nitrogen)under different depths of sand burial.Total buds and rhizome buds increased significantly with increasing burial depth,whereas tiller buds first increased and then decreased,with a peak value at the depth of 20-30 cm.Soil moisture increased significantly with sand burial depth,and was positively correlated with the number of all buds and rhizome buds.Soil total carbon concentration first increased and then decreased with sand burial depth,and total nitrogen concentration was significantly lower under deep sand burial than those at shallow depths,and only the number of tiller buds was positively correlated with soil total nitrogen concentration.These results indicate that soil moisture rather than soil nutrient might regulate the belowground bud bank of P.villosa,and that clonal psammophytes could regulate their belowground bud bank in response to sand burial and the most important environmental stress(i.e.,soil moisture).These responses,as the key adaptive strategy,may ensure clonal plant population regeneration and vegetation restoration in arid sand dunes.

A possibility of saving an endangered endemic of the Lake Baikal shore, <i>Hedysarum zundukii</i>Peschkova (<i>Fabaceae</i>Lindl.) using clonal micropropagation

Hedysarum zundukii Peschkova is one of the Fabaceae endemics of the flora of the Lake Baikal west shore. Because of its very poor renewal by seed production and seedling appearance biotechnological method, clonal micropropagation has been elaborated in order to improve its chances of conservation. A protocol for clonal micropropagation, including introduction, propagation, rooting, acclimatization, field cultivation and prolonged cold storage has been elaborated. Half-dose MS salts, benzylaminopurine 1 mg/dm3 and 2% sucrose were optimal components of the medium for clonal micropropagation. Sucrose was the superior carbon source by comparison with glucose and maltose. It was found that some agar brands were better for propagation, whereas other ones were better for rooting. Transplants produced from acclimatized plantlets vegetated successfully in field conditions, but did not survived in Irkutsk after wintering. However, the same transplants planted into their natural population survived successfully. Micropropagated plantlets retained their ability for propagation in vitro after 10 -12 months of cold storage at 4℃ with illumination. It was concluded that clonal micropropagation may be used as an additional means for conservation of H. zundukii.

北方典型沼泽湿地高低土壤水分下植物群落特征

北方沼泽湿地在水源供给、缓解水土流失、遏制草地沙化等方面具有重要作用,明确其植物群落物种组成和多样性特征对提升其生态系统服务功能具有重要意义。目前,在北方地区开展大尺度湿地植被调查的研究仍相对较少。土壤水分是驱动植物群落发展的主导环境因素之一,为了解高低土壤水分背景下湿地植物群落特征差异及关键驱动要素,对我国7个北方典型沼泽湿地的植物群落物种组成及多样性特征进行了调查,分析了植物群落物种组成及多样性特征与环境因子的关系,以及沼泽湿地植物群落内克隆植物的分布特征。研究结果发现不同沼泽湿地的植物群落物种组成和多样性差异显著,但无明显的地带性分布规律,物种分布呈现区域性。群落物种多样性受降水、温度、土壤养分等多种环境因素的共同影响。沼泽湿地高低土壤水分背景下植物群落的物种组成和多样性差异显著,低土壤水分下植物群落物种多样性指数显著高于高土壤水分下植物群落。低土壤水分下物种多样性主要受降水和总氮影响,而高土壤水分下物种多样性主要受温度和总磷的影响。高土壤水分下克隆植物物种数和盖度在沼泽湿地植物中占有较高的比例,表明克隆植物比非克隆植物更适应高土壤水分环境。研究结果表明了7个沼泽湿地植被的区域性分布特征及受降水和温度的主要影响。随着土壤水分的升高,植物群落多样性降低,但克隆植物的重要性升高。因此,未来降水和温度的变化可能将进一步影响湿地植被的组成和多样性特征。

克隆整合对入侵杂草空心莲子草和本土莲子草生长及光合性能的影响

【目的】在我国,外来入侵植物空心莲子草Alternanthera philoxeroides常与本地莲子草A.sessilis同域分布且占据生态优势。本文探讨克隆整合与空心莲子草强竞争力间的关系。【方法】通过同质园试验,对空心莲子草和莲子草先端与基端匍匐茎的连接处进行保持连接(克隆整合)与剪断处理(无克隆整合),分别测量不同克隆整合处理下2种植物先端分株、基端分株及整个克隆片段地上部分及根系的生长、光合性能及生物量分配情况,比较2种植物克隆整合能力的大小。【结果】克隆整合处理下,空心莲子草先端分株的茎长、基端分株的叶片数及整个克隆片段的叶片数及茎长显著增加,细根数、总根数及一些光合指标(如光补偿点、气孔导度等)也显著提高;莲子草先端分株、基端分株及整个克隆片段的地上(下)生物量、总生物量、粗(细)根数及总根数也显著增加。克隆整合处理下空心莲子草先端分株、基端分株或整个克隆片段的地上(下)生物量、总生物量及一些光合指标(如净光合速率、蒸腾速率、气孔导度)显著高于莲子草。【结论】空心莲子草和莲子草均能在一定程度上从克隆整合中受益,但空心莲子草的克隆整合能力要显著强于本地莲子草,能通过克隆整合作用挤占莲子草的空间生态位,从而形成自然生境中的竞争优势。

壬酸对入侵克隆植物空心莲子草组培苗生长的影响

空心莲子草(Alternanthera philoxeroides)是苋科莲子草属多年生入侵克隆植物,在添加不同剂量的典型挥发性有机化合物壬酸后,本研究对其组培苗的生长形态和生物量等指标进行了测定。结果表明:壬酸添加处理不仅显著降低了空心莲子草组培苗的分枝率、总茎节数、总叶片数量、总匍匐茎长度等形态指标,而且也显著降低了其叶片生物量、匍匐茎生物量、根及愈伤组织生物量、总生物量等生物量指标。其中,2μL和4μL壬酸添加处理下,空心莲子草组培苗的存活率、叶片生物量和匍匐茎生物量未出现显著下降;但6μL和8μL壬酸添加处理,则显著降低了空心莲子草组培苗的存活率,抑制了其根及愈伤组织的形成。本研究预示:一定剂量的壬酸添加处理会改变入侵克隆植物的形态可塑性,减少其克隆分株的产生,进而有可能降低其入侵危害性。

三江源地区人工克隆植物群落生物多样性对初级生产力的影响及机制

克隆植物具有独特的竞争和繁殖方式,这可能会使其构建的群落呈现不一样的生物多样性-生态系统功能关系,但是本议题却极少被研究。本研究利用垂穗披碱草、花苜蓿和鹅绒委陵菜构建了一个生物多样性试验,并将单播和混播重复3次,且将垂穗披碱草作为所有混播的固定物种,以此跨越两个生长季测试生物多样性对生产力的影响。本研究发现,物种丰富度和地上生物量之间并没有线性正相关关系,但是大多数混播的净多样性效应(NE)都是显著的,且NE主要来源于非特征依赖性互补效应(TICE)。较强的TICE主要来自地上垂直空间的互补性利用;其次来自底层物种鹅绒委陵菜光吸收能力的增强。沿着时间和物种丰富度梯度,垂穗披碱草的优势度增强,鹅绒委陵菜的优势度下降,致使特征依赖型互补效应(TDCE)和优势度效应(DE)随之增强,但是它们对NE的贡献有限。另外,以上3种效应均随时间增强。总之,本研究的结果表明克隆植物群落表现出了不一样的多样性-生产力关系模式,并且这种多样性效应主要来自地上垂直空间的互补性利用。

沙地植被恢复过程中克隆植物分布及其对群落物种多样性的影响

以科尔沁沙地草地植被不同恢复程度的 6个群落类型为对象 ,研究植被恢复过程中克隆植物的分布及其对群落结构和功能的影响。研究表明 :在植被恢复过程中 ,克隆植物 (主要是密集型克隆植物 )对群落环境的改变和群落生态功能的维持起主导作用 ,但克隆植物在群落中过高的优势度有可能导致群落物种丰富度和物种多样性的下降。恢复梯度上密集型克隆植物的重要值始终高于游击型克隆植物 ,说明密集型克隆植物对环境的适应能力和对群落环境的改造能力更强。

根茎禾草沙鞭的克隆基株及分株种群特征

在内蒙古沙地站对根茎禾草沙鞭的观测实验发现，沙鞭具有规则的克隆生长、“游击型”克隆构型和相当快的克隆扩展。其地下根茎的寿命至少２年。这些发现指示着该植物种可能具有很强的克隆整合。对内蒙古沙地站和内蒙古草原站的单种沙鞭分株种群的比较和在各站对单种和混交沙鞭分株种群的比较发现，不同地点和在不同群落条件下的沙鞭分株种群在许多重要性状上都存在差异。这些结果暗示着克隆可塑性对沙鞭生态适应性的可能贡献。关于沙鞭克隆整合和克隆可塑性的进一步研究是必要的。

克隆植物的水分生理整合及其生态效应

水分生理整合是克隆植物生理整合过程中非常重要的一部分,是克隆植物生长发育和生态适应过程中的重要机制之一。本文主要从理论上对克隆植物水分生理整合的存在性、方向性、整合的程度、范围及其与克隆植物的功能分工、表型可塑性和觅养行为、风险分摊等行为表现的关系进行了深入分析,并对迄今有关克隆植物水分整合的最新研究进展和研究方法进行了系统总结和评述。提出克隆植物的水分生理整合包括水平和垂直两个方向,而水力提降为垂直方向的水分生理整合提供了一个重要途径。认为在今后,应加强对克隆植物水分生理整合的精确定量化研究,同时,应运用生态学、生理学、生物化学及分子生物学等方法,综合深入地研究克隆植物水分整合的机理。

克隆植物生理整合作用的研究方法及其应用

生理整合作用是克隆植物的一个重要特征,克隆植物所表现出的许多独特的生态学行为,均与其所具有的生理整合效应密切相关.本文总结并分析了迄今为止在研究克隆植物生理整合作用方面所采用的各种方法,并将其归纳为直接和间接方法两个大类.通过这些研究方法的综合运用,克隆植物生理整合效应的机制、格局及其影响因素可以得到更加深入的揭示.在不断深化和拓展现有研究方法的基础上,今后在克隆植物生理整合效应的研究方面,还应较多地关注更为精确的研究方法,以及野外或自然条件下的实地研究.

濒危植物永瓣藤遗传多样性的ISSR分析

采用ISSR分子标记技术研究永瓣藤居群的遗传多样性,用10个ISSR引物对全分布区10个天然居群的190个单株进行扩增,得出总的多态位点百分率为39.2%。Shannon多样性指数（Ho）为0.045～0.101,居群水平上平均值（Hpop）为0.083,物种水平上（Hsp）为0.183,表明遗传多样性均较低。用POPGENE计算出的遗传分化系数GST为0.5672,即居群间的遗传分化占居群总遗传变异的56.72%,显示永瓣藤居群间分化较强烈。地史变迁和植被破坏引起的居群片断化、小居群致使基因流受阻以及永瓣藤自交的繁殖方式都加剧了居群间的遗传分化。研究结果还表明永瓣藤居群间遗传距离与地理距离密切相关。

局部遮光对鹅绒委陵菜基株形态塑性及生物量配置的影响

设置基株、母株、若干克隆片段被分别局部遮光处理,通过测定根、茎、叶的数量性状和生物量,分析局部遮光对鹅绒委陵菜母株、子株、基株形态塑性及生物量配置的影响。结果表明,1)局部遮光对母株株高、叶长、叶宽、叶面积及根系深度有显著影响(P<0.05),局部遮光均可提高母株的株高、叶片长度和总叶面积,不同遮光部位或遮光强度对母株叶宽、单叶面积和根长的影响不同;2)局部遮光对子株叶长、叶面积有显著影响,克隆片段遮光是影响子株叶片大小的主要因素,母株遮光次之;3)局部遮光对克隆片段子株数和新增子株数有显著影响(P<0.05),局部遮光可显著增加基株的克隆片段数(P<0.05),母株遮光对匍匐茎伸长和新克隆片段形成有重要的影响;4)局部遮光对基株根、茎、叶含水量及叶和根生物量累积有极显著影响(P<0.01),遮2个以上克隆片段或遮母株可显著增加基株根生物量累积,但基株完全遮光使根生物量显著低于CK;5)局部遮光对基株茎、叶、根生物量分配比均有极显著影响(P<0.01),遮光对叶分配比影响最大,对茎分配比次之,对根分配比较小;6)局部遮光对基株地上生物量比有极显著影响(P<0.01),遮光部位对基株茎根比和茎叶比有极显著影响(P<0.01),全遮光显著增加基株的茎根比和茎叶比。综上所述,局部遮光对克隆植物鹅绒委陵菜的母株、子株、克隆片段和基株形态塑性和生物量配置有直接的影响。

施氮对空心莲子草(Alternanthera philoxeroides)和莲子草(Alternanthera sessilis)种间关系的影响

自然界的氮素释放总是呈现出空间和时间上的异质性,但关于异质性氮释放对于入侵植物和本地植物种间关系影响的研究相对较少。将入侵植物空心莲子草(Alternanthera philoxeroides)和同属本地植物莲子草(Alternanthera sessilis)分别进行单种种植(12株,无种间竞争)和混种种植(每种6株,有种间竞争),模拟大气氮湿沉降设置由两种不同施氮总量(15g N m^(-2)a^(-1)和30g N m^(-2)a^(-1))和两种不同施氮频率(每5天1次和每15天1次)交叉组成的4种施氮处理,并以不施氮为对照。施氮总量的增加显著促进了两种植物的生长,但对两种植物的种间竞争关系没有显著影响。施氮频率对两种植物的生长以及种间竞争关系都没有显著影响。两种植物在面对竞争时表现出不同的生物量分配策略,空心莲子草将更多的生物量分配到茎,而莲子草将更多的生物量分配到根。在全球变化的背景下,大气氮湿沉降可能会改变两种植物的种群结构和动态,但可能对这两种植物的种间关系影响较小。