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

Aims Plants can benefit from heterogeneous environments via disproportionately increasing resource harvesting in resource-rich patches.Their initial growing positions with respect to resource patches may thus have important influences on their performance and relative competitive ability.Such impacts may differ between species with contrasting spatial architectures.However,the potential influence of initial growing positions in heterogeneous environment on plant growth and competition has largely been ignored.Methods We grew the phalanx plant Carex neurocarpa and the guerrilla plant Bolboschoenus planiculmis alone or in competition in a heterogeneous environment consisting of high-and low-nutrient soil patches.In treatments without competition,one ramet of each species was grown in either a high-or a low-nutrient patch in the heterogeneous environment.In treatments with competition,a ramet of the target species was grown in either a high-or a low-nutrient patch,and a ramet of the competitor species was grown in the same patch as the target species or an adjacent patch with a different nutrient level.Important Findings Without competition C.neurocarpa produced more biomass and ramets when initially grown in a high-nutrient patch than when initially grown in a low-nutrient patch.With competition,these differences disappeared.Consequently,competitive intensity on C.neurocarpa was higher when it initially grew in a high-nutrient patch than when it initially grew in a low-nutrient patch.These impacts were independent of the initial position of its competitor.By contrast,the initial positions of B.planiculmis did not influence its growth or competitive response.Therefore,in heterogeneous environments,initial growing positions of clonal plants may influence their performance in competition-free environments and may also affect their relative competitive ability,and these effects may depend on spatial architecture of the plants.

Adaptive plasticity in response to light and nutrient availability in the clonal plant Duchesnea indica

Phenotypic plasticity enables plants to buffer against environmental stresses and match their phenotypes to local conditions.However,consistent conclusive evidence for adaptive plasticity has only been obtained for a few traits.More studies on a wider variety of plant functional traits and environmental factors are still needed to further understand the adaptive significance of plasticity.We grew 21 genotypes of the stoloniferous clonal plant Duchesnea indica under different light and nutrient conditions,and used selection gradient analyses to test the adaptive value(benefits)of morphological and physiological plasticity responding to variation in light and nutrient availability.Plants grown in shade exhibited lower values for fitness measures(fruit number,ramet number and biomass),shortened thinner internode length and decreased adult leaf chlorophyll content,but higher petiole length,specific leaf area and old leaf chlorophyll content,than plants grown without shade.Plants grown in the low nutrient condition had shorter petiole length,thicker and smaller leaf area,lower chlorophyll content,but higher fruit number and root:shoot ratio than plants grown under the high nutrient condition.Selection gradient analyses revealed that plasticity of petiole length and old leaf chlorophyll content in response to light variation was adaptive,and plasticity of old and adult leaf chlorophyll content in response to nutrient variation was adaptive.Therefore,the adaptive value of plasticity in different traits depends on the specific ecological context.Our findings contribute to understanding the adaptive significance of phenotypic plasticity of clonal plants in response to environmental variation.

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.

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

Resource sharing in the different parts of the clonal white clover plant (Trifolium repens L.) was investigated in this study. The results showed that the integration of water and nitrogen metabolism occured among parental, young and old branches of a plant when water passed through its stolons. Under the sufficient supply of light, water and nutrients from soil the newly developed branches showed similar capacity in taking in sufficient water and nitrogen to that of old branches. The development of the new branches did not affect the growth of the old and parental branches attached. The results also indicated that energy values in roots was significantly related with plant age, however, the energy values were various in the different parts of a plant.

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.

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.

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.

东北退化草原恢复演替系列羊草和寸草无性系种群构件营养繁殖特征比较

营养繁殖是无性系草本植物种群更新的主要方式,根茎型草本植物通过营养繁殖形成的构件年龄结构在种群现状分析、动态预测和恢复演替动态分析中发挥着重要作用。本研究以东北退化草原恢复演替系列5个阶段中主要无性系草本植物羊草和寸草为研究对象,对两植物种分株和根茎的年龄结构、各龄级分株生产力、根茎贮藏力以及分株和根茎营养繁殖力进行了对比分析。结果表明:各恢复演替阶段羊草和寸草分株均呈增长型年龄结构,根茎呈稳定型或增长型年龄结构。不同恢复演替阶段羊草分株生产力和根茎贮藏力均强于寸草。随草原恢复演替的进程,羊草1 a根茎贮藏力呈显著上升趋势,寸草2 a分株生产力呈显著下降趋势。羊草与寸草共生的恢复演替阶段中,羊草根茎营养繁殖力均强于寸草。总体上,不同恢复演替阶段中羊草与寸草构件年龄结构特征具有相似性,但随草原恢复演替的进程,羊草种群增强幼龄和壮龄分株营养繁殖力的繁殖策略较寸草种群仅增强幼龄分株营养繁殖力的繁殖策略更有利于种群的维持和扩展。羊草将逐渐取代寸草成为群落中的优势种。

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。

洞庭湖湿地短尖薹草(Carex brevicuspis)种群克隆生长对泥沙淤积的适应

泥沙淤积是影响湿地植物生存和生长的重要因素。克隆植物是湿地生态系统的主要植物类型之一。在自然水文条件下,湿地克隆植物种群对不同淤积速率的响应研究相对较少。本研究以洞庭湖湿地优势克隆植物短尖薹草(Carex brevicuspis)为对象,通过连续3年的野外控制实验,研究了不同淤积速率(0、2、4、6 cm/a,分别对应对照组,低、中和高淤积速率组)对湿地克隆植物种群的影响。结果表明:淤积速率对短尖薹草的种群密度影响显著,淤积处理的密度显著低于对照处理。随着淤积速率的增加,密度下降,地下/地上生物量比增加,高淤积速率下种群的密度最低,地下/地上生物量比最高。与对照处理相比,泥沙淤积促进了更多的短根(<10 cm)、长根茎(≥1 cm)和游击型克隆分株的形成,长根茎的长度随淤积速率的增加而增加。高淤积速率下的长根茎数量较低,但其根长最长,表明其克隆生长策略由密集型向游击型转变。由此可见,短尖薹草种群可通过对密度、生物量分配、根系长度和克隆生长策略的调节,有效地应对不同泥沙淤积速率的影响。

Architectural Plasticity in Response to Soil Moisture in the Stoloniferous Herb, Duchesnea indica

Architectural plasticity of clonal plants may enhance exploitation of soil moisture heterogeneity by the plants. The plasticity of clonal architecture in response to soil moisture in the stoloniferous herb, Duchesnea indica Focke, was investigated in an experiment with different soil moisture contents as treatments, i.e. 40%, 60%, 80%, 100% of the maximum moisture content of soil (MMCS). As soil moisture content increased, the spacer length, ramet density, branching intensity and branching angle of D. indica plants changed by quadratic curve. And the optimum habitat for the plants was at 80% of the MMCS. This architectural plasticity in D. indica was simulated through the Dynamic Logistic Model. The imitative effect was statistically satisfactory. Its architectural plasticity observed here may allow the species to show foraging behavior in its habitat where soil moisture is patchily distributed.

Phenotypic Plasticity in Response to the Heterogeneous Water Supplyin the Rhizomatous Grass Species, Calamagrostis epigejosin the Mu Us Sandy Land of China

Calamagrostis epigejos (L.) Roth. is a perennial grass with slender and long rhizome segments between interconnected neighbor ramets. To investigate the phenotypic plasticity in response to the heterogeneous soil water supply, ramet pairs of the species were subjected to heterogeneous water supply by which either mother ramets or daughter ramets were in high or low soil water supply, respectively, in the Maowusu (Mu Us) Sandy Land of Nei Mongol. The results showed that the phenotypic characteristics of the individual ramets of C epigejos were greatly influenced by the heterogeneous water supply. The ramets treated with high water supply significantly produced more new rhizomes and more offspring (ramets), and accumulated more shoot biomass, and allocated more biomass to their shoots than those treated with low water supply. In comparison with the daughter ramets in homogeneous soil water supply, phenotypic characteristics, in terms of new rhizome growth, the production of new offspring, and the biomass allocation pattern, of the daughter ramets within the pairs of the species were not significantly changed, no matter that high or low soil water supply to mother ramets. The phenotypic responses of mother ramets to soil water supply were similar to those of daughter ramets. From these results, it is inferred that the interconnected ramets of C epigejos response phenotypically to their local soil water rather than to the soil water experienced by the interconnected ramets. The interconnected ramets of C epigejos might be independent of each other in water relationship, although they are physically interconnected with rhizome segments. The physiological independence of interconnected ramets might facilitate the risk spreading and thus enhance the genet survivorship under the frequent drought stresses in Mu Us Sandland.

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。

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。

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。

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.

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。