Within population genetic differentiation in traits affecting clonal growth: Festuca rubra in a mountain grassland

Festuca rubra , a clonal grass of mountain grasslands, possesses a considerable variability in traits related to spatial spreading (rhizome production, length and branching; tussock architecture). Since these traits highly influence the success of the species in a spatially heterogeneous system of grasslands, a combined field and growth chamber approach was adopted to determine the within-population variation in these parameters. Clones were sampled in a mountain grassland (The Krkono?e Mts., Czech Republic); the environment (mean neighbour density) of individual clones varied highly. Before the clones were collected, shoot demography and tussock architecture within these clones were recorded in the field for four seasons. Their clone identity was determined using DNA RAPD. Vegetatively propagated plants from these clones were cultivated in a common garden experiment to demonstrate variation in tussock growth and architecture. Their response to change in red/far red light ratio was determined in the growth chamber. Highly significant variation among clones was found in almost all parameters. In the common garden, the clones differed in tussock growth (mean tillering rate), architecture (mean shoot angle, mean tussock density) and proportion of flowering shoots. In the growth chamber, both the aboveground parameters and parameters of the rhizome system were strongly affected by red/far red ratio; among-clone variation was also almost always significant. The genotype × environment interaction was significant for tillering rate and rhizome architecture. The structure of the rhizome system (which is the major component of clonal spread in space) is a complex result of several components whose inter-clone variations differ: (i) genetically determined mean rhizome system size, (ii) overall plasticity in rhizome system size (with no significant genetic variation in plasticity), and (iii) genetically determined plasticity in rhizome architecture. Because of the variation in plasticity in rhizome architecture, some c lones seemed to possess the ability to exploit a favourable habitat patch by producing short branches when there; whereas the remaining clones appeared to possess only a simple escape mechanism from unfavourable patches. Environmental variation in the light levels in the studied grassland is fine grained; horizontal growth rates of F. rubra are sufficient to make genets experience different patches in their lifetime. The high variation in both genotype means and plasticities is likely to be due to selection early in genet life in an environment which is heterogeneous at a fine scale.     

Morphological plasticity ofFestuca rubra clones from three neighbouring communities in response to red: Far-red levels

Morphological parameters ofFestuca rubra clones and their response to differences in the red/far red ratio (R : FR) were investigated in a growth chamber experiment. The twenty-four clones tested came from 15 micro-sites in three neighbouring meadow communities in the Krkono?e Mts. (Czech Republic). The community types were characterized by different canopy height and structure, and by different radiation conditions (relative R : FR) within the canopies. Low R : FR treatment resulted in reduced tillering and stimulated shoot elongation in most of the clones. In some clones, low R : FR ratios stimulated extravaginal tillering and rhizome system formation. The origin of the clones (i.e., community type) explained a part of variation in morphological parameters, but did not explain variation in the response to R : FR levels. Evidence for a consistent relationship between clone performance and radiation environment in the micro-sites from where the clones originated was not found. It seems that there is only limited selection ofF. rubra clones (ecotypes) specialized for particular community types and no selection of clones specialized for particular micro-sites within communities.     

Identification of the main site factors and management intensity affecting the establishment of Short-Rotation-Coppices (SRC) in Northern Italy through stepwise regression analysis

Data collected from 183 poplar and 102 willow SRC experimental plots, located in Central-North Italy, were subjected to stepwise regression analysis to acquire information on the environmental factors affecting plant survival and productivity in the first two-year rotation cycle. Nine Populus ×canadensis Mönch, eight P. deltoids Bartr. clones and four hybrids of Sali× matsudana Koidz were included in analysis. Independent variables were: annual and seasonal water availability (rainfall and irrigation), annual mean air temperature, soil texture, pH, N and organic matter content, planting density and management intensity. Dependent variables were: a) mean annual yield during the first two-year rotation cycle in tons per hectare per year of dry matter (Odt·ha^?1·y^?1); b) plant survival at the end of the second year from planting (%). Water availability resulted the main variable driving plant survival and biomass production in both poplar and willow clones. Water availability appeared to be the principal factor affecting the establishment of poplar and willow energy plantations in the Po valley. Possible variations in the rainfall regime consequent to climate changes could seriously influence land suitability to SRC. Experimental data also indicate that choice of planting density may increase the biomass yield during the first two-year especially with P. deltoides clones.     

Evolutionary impacts of the goldenrod ball gallmaker on Solidago altissima clones

Summary Three ramet clones of Solidago altissima were grown under greenhouse conditions to determine the effects of varying levels of attack by the goldenrod ball gallmaker (Eurosta solidaginis) on biomass allocation, leaf senescence rate and rhizome connections among ramets. The results, examined at both the individual ramet level and the clone level, showed that galled ramets became isolated from their clone through deterioration of rhizome connections. Gall effects were only observed at the ramet level although rhizome connection effects were detected at both the ramet and clone levels. The goldenrod ball gallmaker may therefore have little evolutionary impact on large clones but could appreciably affect newly established clones.     

砷胁迫对三七皂苷和黄酮含量、关键酶活性的影响及其蛋白质组分析

通过田间小区试验,研究不同As浓度(0、20、80、140、200和260 mg·kg^-1)连续2年处理对3年生三七根茎(主根、须根、剪口)和茎叶中皂苷、黄酮和As含量、三七鲨烯合酶、苯丙氨酸解氨酶和查尔酮合酶活性,以及叶片蛋白质组的影响,探讨连续2年砷胁迫对三七主要药效成分影响的酶学和蛋白质组学机制.结果表明: 三七须根中总皂苷含量随砷处理浓度的增加而降低.140 mg·kg^-1As处理下,茎叶和剪口总皂苷大于对照.根茎部三七鲨烯合酶活性较茎叶高.三七各部位黄酮含量均随砷处理浓度的增加而降低.140 mg·kg^-1As处理下,根茎部查尔酮合酶和苯丙氨酸解氨酶活性较茎叶高.茎叶和剪口查尔酮合酶活性低于对照,苯丙氨酸解氨酶的活性高于对照.三七各部位砷含量均随砷处理浓度增加而增加.须根中砷含量大于其他部位.140 mg·kg^-1As处理下,与对照相比,差异表达的蛋白质点达21个.叶片蛋白质组中下调的蛋白质包括磷酸核酮糖激酶、热激蛋白、NAD(P)-结合酶、单脱氢抗坏血酸还原酶和细胞色素b6-f复合物铁硫亚基.上调的蛋白质为CDC27家族蛋白、酸性内切壳多糖酶、共生受体激酶、异黄酮还原酶、DAHP合成酶、蛋白激酶、苹果酸脱氢酶、乙二醛酶和谷氨酰胺合成酶.经过连续2年的砷胁迫, 三七各部位砷含量增加,不仅影响了三七叶片光合作用和能量的合成,还减弱了抗氧化和抗逆能力,诱导了代谢解毒物质的酶表达,导致皂苷和黄酮含量降低.三七对砷的耐受阈值为140 mg·kg^-1.     

The Impact of Physical Disturbance and Increased Sand Burial on Clonal Growth and Spatial Colonization of Sporobolus virginicus in a Coastal Dune System

Dune plants are subjected to disturbance and environmental stresses, but little is known about the possible combined effects of such factors on growth and spatial colonization. We investigated how clones of Sporobolus virginicus , a widespread dune species, responded to the independent and interactive effects of breakage of rhizomes, breakage position and burial regime. Horizontal rhizomes were severed at three different internode positions relative to the apex to span the range of damage by disturbance naturally observed or left intact, and apical portions exposed to two burial scenarios (ambient vs. increased frequency) for three months in the field. The performance of both parts of severed rhizomes, the apical portion and the remaining basal portion connected to clone containing four consecutive ramets, was compared with that of equivalent parts in intact rhizomes. Apical portions severed proximal to the third internode did not survive and their removal did not enhance branching on their respective basal portions. Severing the sixth or twelfth internode did not affect survival and rhizome extension of apical portions, but suppressed ramet production and reduced total biomass and specific shoot length. Their removal enhanced branching and ramet production on basal portions and changed the original rhizome growth trajectory. However, the gain in number of ramets in basal portions never compensated for the reduction in ramet number in apical portions. Recurrent burial increased biomass allocation to root tissues. Burial also stimulated rhizome extension only in intact rhizomes, indicating that disturbance interacts with, and counteracts, the positive burial effect. These results suggest that disturbance and recurrent burial in combination reduces the regeneration success and spread capacity of S . virginucus . Since global change leads to increasingly severe or frequent storms, the impact of disturbance and burial on clones could be greater in future and possibly prevent colonization of mobile dunes by the species.     

Rhizome Growth and Clone Development in Anemone nemorosa L.

Studies of natural populations indicate that clones grow radially,soon developing a hollow centre which may be invaded by newgenotypes. In the populations studied, individual rhizomes elongate byan average of 2.5 cm per year. Growth is sympodial, the terminalbud forming an aerial shoot and further elongation occurringfrom an axillary bud. The oldest rhizome segment found was 7 years with most rhizomesbeing 3 or 4 years old. Because there is no apparent senescence,individual clones may persist for very long periods, possiblyhundreds of years. A computer model of rhizome growth was used to postulate theextent of intermixing of old clones. It indicated that old clonesbecome very fragmentary and totally inmixed with their neighbours,one ‘clump’ often representing several clones. To supplement the model, plants from a woodland with an unbrokencarpet of Anemone nemorosa were collected, 27 morphologicalcharacters measured and the data analysed using principal componentsanalysis and cluster analysis. These supported the hypothesisthat old clones are large and fragmentary with complete intermixing. The possible role of soil factors in influencing rhizome extensionis discussed and the strategy of A.nemorosa is compared withthose of its close associates in the pre-vernal woodland herblayer. Anemone nemorosa L., wood anemone, rhizome growth, clone development, computer model, vegetative reproduction     

In vitro propagation of <Emphasis Type="Italic">Cymbidium goeringii</Emphasis> Reichenbach fil. through direct adventitious shoot regeneration

The influence of 2,4-dichlorophenoxyacetic acid (2,4-D), benzyladenine (BA), and thidiazuron (TDZ) on direct rhizome induction and shoot formation from rhizome explants of Cymbidium goeringii was explored. Rhizome segments obtained from in vitro seed cultures of C. goeringii were placed on Murashige and Skoog (MS) medium incorporated with 5, 10, 20, or 40 µM 2,4-D and 1, 2, 4, or 8 µM BA or TDZ alone or in combination with 20 µM 2,4-D. The explants developed only rhizomes on MS medium with or without 2,4-D. The highest percent of rhizome formation (100%) was obtained on MS medium incorporated with 20 μM of 2,4-D. The morphology and number of rhizomes varied with the level of 2,4-D in the medium. Direct adventitious shoot formation was achieved on medium incorporated with BA or TDZ. The adventitious shoots produced per explant significantly increased with the supplementation of 2,4-D to cytokinin-containing medium. The highest mean of 21.8 ± 1.8 shoot buds per rhizome segment was obtained in medium fortified with 20 μM 2,4-D and 2 μM TDZ. The greatest percent of root induction (100%) and the mean of 5.3 ± 1.1 roots per shoot were achieved on ½ MS medium incorporated with 2 μM of α-naphthaleneacetic acid. About 97% of the in vitro-produced plantlets acclimatized in the greenhouse. An efficient in vitro propagation protocol was thus developed for C. goeringii using rhizome explants.     

德国鸢尾‘常春黄’花芽分化的形态观察及两种代谢产物的动态变化

鸢尾是世界著名观赏花卉,为研究其花芽分化期的形态和生理指标变化情况,我们以德国鸢尾两季花品种‘常春黄’（Iris germanica cv. Lovely Again）为材料,运用扫描电镜（SEM）观察了德国鸢尾‘常春黄’的花芽分化过程。结果表明：整个形态分化过程可分为6个阶段：花序原基分化期、外轮花被分化期、雄蕊分化期、内轮花被分化期、雌蕊分化期、髯毛形成期。结合上述形态分化过程,分别取其二次花花芽分化时期的顶芽、根茎和叶片部位,以蒽酮比色法测定可溶性糖,以考马斯亮蓝G-250法测定蛋白质含量。结果表明：可溶性糖在花序原基分化的初始阶段含量最高,且在3个部位的含量大小关系始终是：根茎﹥叶片﹥顶芽;蛋白质含量呈先上升后下降的趋势,蛋白质含量的峰值出现于花序伸展初期。     

Volatile constituents of Zingiber officinale rhizomes produced by in vitro shoot tip culture

Plantlets with rhizomes were produced in vitro from shoot tips of Zingiber officinale grown in both modified Gamborg's B5 (B5) and Murashige-Skoog (MS) media supplemented with various levels of growth regulators. The rhizomes accumulated the volatile oils similar to those formed in the original rhizome. In the oil from the rhizome grown in the modified B5 medium, the acyclic oxygenated monoterpenes predominated, while the oil from the rhizome grown in the modified MS medium consisted mainly of sesquiterpenes.     

Direct and indirect effects of two herbivore species on resource allocation in their shared host plant: the rhizome galler Eurosta comma, the folivore Trirhabda canadensis and Solidago missouriensis

We examined the effects of the rhizome galling fly, Eurosta comma (Wiedemann), on rhizome mass and nitrogen allocation in a clone of its goldenrod host plant, Solidago missouriensis Nutt. In comparison to ungalled ramets, galled ramets initiated significantly fewer new rhizomes, and allocated less mass to leaves and stems and more to roots. Galled ramets had lower concentrations of nitrogen in roots and rhizomes but leaf and stem nitrogen concentrations were not affected. In the second year of our study, outbreaks of the leaf-eating beetle, Trirhabda canadensis (Kirby), occurred in three of our four study clones, removing ∼20%, ∼50%, and 100% of leaf area from clones 2–4, respectively. In the most heavily grazed clones, the influence of rhizome galls on plant resource allocation was least pronounced. Despite the overwhelming immediate impact of grazing, the presence of a gall population may be important because they decrease the ability of S. missouriensis clones to initiate new rhizomes and hence to recover from defoliation. Received: 28 December 1997 / Accepted: 28 December 1998     

空心莲子草地下茎克隆繁殖特征

空心莲子草是一种原产于南美洲的苋科多年生草本植物,目前在许多地方已经成为一种危害十分严重的外来入侵植物。通过地下茎等营养器官进行无性繁殖是其主要繁殖方式。本文以空心莲子草的地下茎为实验材料,对其克隆繁殖特征进行了研究。研究结果表明:(1)地下茎的节是克隆繁殖的必要条件,节的有无决定克隆繁殖是否发生;(2)地下茎可以通过控制单位节上的出芽率来调节其克隆生长过程,从而使克隆繁殖结果更有利于整个种群的生长;(3)地下茎的粗细程度对其克隆繁殖也有显著影响。空心莲子草地下茎的单位节数与其单位节出芽率、无性系小株的高度和地上部分的节数之间存在密切联系。     

虎杖根茎蒽酯类化合物细胞化学定位和含量测定（简报）

Anthraquinones were histochemically locayed and content were determined in rhizome of Polygonum cuspidatum. Anthraquinones were located in the parenchyma cells of rhizome, including vascular ray, part of parenchyma cell in phloem, cortex and pith. Phelloderm and ray initial also accumulated a small amount anthraquinones. The content of total anthraquinones was highest in pith that consisted of parenchyma cells, and higher in bark (including phloem, cortex and periderm) than in xylem. The content of total anthraquinones was highest in three-year-old rhizome, and higher in biennial rhizome than in annual rhizome. It suggests that correlation exist between accumulation of anthraquinones and the growth age of rhizome.     

Life history trade-offs in Amphibromus scabrivalvis (Poaceae): allocation to clonal growth,storage, and cleistogamous reproduction

Life history trade-offs among clonal growth, storage, and sexual reproduction were investigated in the perennial grass Amphibromus scabrivalvis in relation to soil nutrients. This species exhibits clonal growth by producing rhizomes and stores reserves in the form of basal corms; seeds are matured in cleistogamous spikelets on panicles enclosed within the leaf sheaths along each culm. Ten seed-derived genotypes (clones) were separated into 72 ramets and planted in the greenhouse. Control ramets received only water while the remainder received fertilizer applied every 2 wk. Twenty-four ramets were harvested per clone at 11, 20, and 26 wk. The dry mass of corms, rhizomes, roots, shoots, and seeds were recorded. Biomass partitioning to rhizomes provided a measure of carbon allocation to clonal growth, partitioning to corms provided a measure of allocation to storage, and partitioning to seeds provided a measure of allocation to sexual reproduction. Allocation to most organs was significantly influenced by clone identity; fertilizer significantly increased allocation to corms and seeds at 20 wk, but never affected rhizome allocation at any age. Corm allocation increased from 2% at 11 wk to 27% at 26 wk; rhizome allocation decreased from 10% at 11 wk to 3% at 26 wk. Significant negative relationships were detected for rhizome vs. seed and corm vs. rhizome allocation in fertilized clones at 20 wk. This suggests an age-dependent physiological life history trade-off between clonality and sexual reproduction and between clonality and storage. In contrast, a significant positive relationship was consistently noted for corm vs. seed allocation in fertilized and unfertilized clones at 20 and 26 wk. The absence of a trade-off between storage and sexual reproduction may indicate that these two processes are not necessarily mutually exclusive components of life history.     

Moderate abiotic stresses increase rhizome growth and outgrowth of axillary buds in Alstroemeria cultured in vitro

Alstroemeria is multiplied in vitro by forced outgrowth of lateral rhizomes from rhizome explants. The multiplication rate is very low because of strong apical dominance and poor rhizome growth. We report here that moderate abiotic stresses stimulate both rhizome growth and outgrowth of lateral rhizomes, and accordingly increase multiplication. Rhizome explants were exposed to heat by a hot-water treatment (HWT) or by a hot-air treatment. Both increased rhizome growth when applied for 1 or 2?h in the range of 30?C40?°C. The maximal enhancement was 75?%. Other abiotic stresses were also examined. Cold (0?°C) and partial anaerobiosis increased rhizome growth significantly. The increases brought about by drought and salinity were not statistically significant. Because underground storage tissues like rhizomes are adaptations to survive climatic stresses, we presume that the increased sink-strength of rhizomes induced by moderate stress is related to stress adaptation. Moderate heat stress (38?°C HWT, 1?h) also resulted in protection of Alstroemeria plantlets from severe heat stress (45?°C HWT, 1?C2?h) a few hours after the moderate stress. All abiotic stresses also increased the outgrowth of lateral rhizomes.     

Response of Solidago canadensis clones to competition

Summary Transplants of ten Solidago canadensis clones were grown under high and low competition in the field to determine whether clones differed in survival, growth, and reproduction under natural conditions. Transplants had higher probability of survival and flowering and were larger in all measures of size when competition was experimentally reduced. Clones differed in almost all these measures of success, but only when variance among transplants within clones was reduced by excluding transplants that experienced heavy herbivore damage. Differences among clones were more apparent under low competition than under high competition, despite higher coefficients of variation within clones under low competition. Adjusting transplant size for initial size (parent ramet rhizome mass) did not change these results, although clones did differ in parent rhizome mass. All of these results suggest that there is little potential for selection to discriminate among these clones. Despite the strong differences in transplant performance between the competition treatments and among clones, the clones did not differ in competitive ability-almost none of the clone x competition interactions were significant. In addition, the measures of success of each clone were usually positively correlated between the high and low competition treatments, suggesting there were no tradeoffs between performance under high and low competition for these clones.     

Expressed sequence tags and molecular cloning and characterization of gene encoding pinoresinol/lariciresinol reductase from Podophyllum hexandrum

Podophyllotoxin, an aryltetralin lignan, is the source of important anticancer drugs etoposide, teniposide, and etopophos. Roots/rhizome of Podophyllum hexandrum form one of the most important sources of podophyllotoxin. In order to understand genes involved in podophyllotoxin biosynthesis, two suppression subtractive hybridization libraries were synthesized, one each from root/rhizome and leaves using high and low podophyllotoxin-producing plants of P. hexandrum. Sequencing of clones identified a total of 1,141 Expressed Sequence Tags (ESTs) resulting in 354 unique ESTs. Several unique ESTs showed sequence similarity to the genes involved in metabolism, stress/defense responses, and signalling pathways. A few ESTs also showed high sequence similarity with genes which were shown to be involved in podophyllotoxin biosynthesis in other plant species such as pinoresinol/lariciresinol reductase. A full length coding sequence of pinoresinol/lariciresinol reductase (PLR) has been cloned from P. hexandrum which was found to encode protein with 311 amino acids and show sequence similarity with PLR from Forsythia intermedia and Linum spp. Spatial and stress-inducible expression pattern of PhPLR and other known genes of podophyllotoxin biosynthesis, secoisolariciresinol dehydrogenase (PhSDH), and dirigent protein oxidase (PhDPO) have been studied. All the three genes showed wounding and methyl jasmonate-inducible expression pattern. The present work would form a basis for further studies to understand genomics of podophyllotoxin biosynthesis in P. hexandrum.