Phenology of glucosinolate concentrations in roots,stems and leaves of Cardamine cordifolia

Total concentrations of isothiocyanate-yielding glucosinolates (IYG) were measured in roots, stems, basal leaves and cauline leaves of the herbaceous perennial Cardamine cordifolia (bittercress, Cruciferae), sampled at three sites in the Colorado Rockies during 1981. Significant variation in quantity was partitioned among plant parts, among sampling dates throughout the growing season, and among the three sites. Roots and basal leaves maintained high and similar concentrations of IYG through the season, while cauline leaves and stems showed seasonal declines, associated partly with flowering. Roots also consistently produced oxazolidinethione-yielding glucosinolates (hydroxylated analogues of IYG), whereas above-ground parts were variable for the presence of these compounds. Seasonal and plant-part variability in glucosinolate content and spatial patchiness of glucosinolate phenotypes contribute to the variation in herbivore occurrence and damage documented in previous studies of this native crucifer.     

Concentration of glucosinolates in relation to habitat and insect herbivory for the native crucifer Cardamine cordifolia

Understanding plant-insect interactions requires further data on herbivory in relation to the variation in concentration of characteristic secondary compounds. We report here analyses of the glucosinolate contents for a native perennial, montane crucifer Cardamine cordifolia in relation to: (a) plant characteristics; (b) insect herbivory; and (c) habitat. The only pattern of variation of glucosinolate content with leaf characteristics found was an inverse correlaton between leaf weight and total isothiocyanate-yielding glucosinolates (IYG) in shaded plants. There was a highly significant, negative relationship between total IYG and leaf damage by insects, particularly in typical shaded habitats. Higher insect-caused damage on denser, smaller leaves of plants from the driest soils was observed. Additionally, plants occurring in sun-exposed habitats from the beginning of the growing season, both naturally and experimentally, had similar (or lower) concentrations of total IYG, and were significantly more damaged by insects, than those in the more usual shaded habitats. The experimental removal of shade cover in mid-season resulted in significantly elevated quantities of total IYG in the first year, with a relaxation of that stress-induced response in the second year. We suggest that the insect herbivore guild on Cardamine cordifolia responds to concentration and composition of glucosinolates and exerts its greatest pressure on plants with lower concentrations. Differential herbivory, consumption mediated in part by glucosinolate concentration, appears to contribute to microhabitat occurrence of C. cordifolia.     

Variation of glucosinolate accumulation among different organs and developmental stages of Arabidopsis thaliana

The glucosinolate content of various organs of the model plant Arabidopsis thaliana (L.) Heynh., Columbia (Col-0) ecotype, was analyzed at different stages during its life cycle. Significant differences were noted among organs in both glucosinolate concentration and composition. Dormant and germinating seeds had the highest concentration (2.5-3.3% by dry weight), followed by inflorescences, siliques (fruits), leaves and roots. While aliphatic glucosinolates predominated in most organs, indole glucosinolates made up nearly half of the total composition in roots and late-stage rosette leaves. Seeds had a very distinctive glucosinolate composition. They possessed much higher concentrations of several types of aliphatic glucosinolates than other organs, including methylthioalkyl and, hydroxyalkyl glucosinolates and compounds with benzoate esters than other organs. From a developmental perspective, older leaves had lower glucosinolate concentrations than younger leaves, but this was not due to decreasing concentrations in individual leaves with age (glucosinolate concentration was stable during leaf expansion). Rather, leaves initiated earlier in development simply had much lower rates of glucosinolate accumulation per dry weight gain throughout their lifetimes. During seed germination and leaf senescence, there were significant declines in glucosinolate concentration. The physiological and ecological significance of these findings is briefly discussed.     

Changes in glucosinolates during crop development in single- and double-low genotypes of winter oilseed rape (Brassica napus): II. Profiles and tissue-water concentrations in vegetative tissues and developing pods

The concentrations of glucosinolates in the tissue water of leaves, stems, floral buds and developing pods were measured at defined stages of development in four oilseed rape cultivars known to have different seed glucosinolate concentrations (Bienvenu, Ariana, Cobra and Capricorn). Five alkenyl, two aromatic and three indolyl compounds were identified in the vegetative and reproductive organs. Substantial differences developed in the profiles of compounds present during vegetative growth. The 2-hydroxy-3-butenyl glucosinolate was primarily associated with developing and mature seeds and germinated seedlings. The 4-pentyl glucosinolate occurred mainly during the later stages of vegetative growth in spring, when leaves contained higher concentrations than stems, and during the early stages of flowering. The 2-phenylethyl and 3-indolymethyl glucosinolates were present earlier in vegetative growth when similar concentrations were present in leaves and stems. Differences between cultivars in the tissue-water concentrations of individual glucosinolates were small during vegetative growth. The leaves of Cobra and Capricorn had smaller concentrations of the 3-pentyl glucosinolate than Bienvenu and Ariana especially early in spring, and the stems of Capricorn had smaller concentration of the 3-pentyl and 2-phenylethyl glucosinolates. Greater differences between cultivars developed during pod growth and involved large increases in the concentrations of the 2-hydroxy-3-butenyl and 3-butenyl glucosinolates, especially in Bienvenu and Ariana. The implications of these changes in the types and concentrations of glucosinolates in the different organs for the incidence of pests and diseases are discussed.     

克里雅绿洲旱生芦苇根茎叶C、N、P化学计量特征的季节变化

旱生芦苇在水分限制、元素匮乏的环境条件下,经长期进化适应形成了自身独特的生理生态特征,研究其C、N、P化学计量特征随生长季节的变化规律有助于深入了解该植物生存和适应策略。系统分析了克里雅绿洲旱生芦苇根、茎、叶的C、N、P化学计量特征及其季节动态,深入探讨了不同生长季、不同器官以及两因素的交互作用对以上特征的影响。结果表明:旱生芦苇C、N、P含量均值分别为393.36、12.43、1.25 mg/g,C∶N、N∶P、C∶P均值分别为54.55、9.96、441.27。整个生长季内芦苇各器官间C、N、P平均含量的变化规律一致,为叶茎根,C、N、P化学计量比的变化规律不一致;芦苇C含量随生长季节的变化不断增加,N、P随季节的变化逐渐减少,C、N、P化学计量比随季节的变化规律也不尽相同。对芦苇C、N、P含量及其化学计量比整体变异来源分析显示,生长季节的变化对芦苇C、P、C∶N、C∶P变化的贡献大于器官间差异,器官间差异对芦苇N、N∶P变化的贡献大于生长季节的变化;说明芦苇生长发育过程中各生长季各器官对元素的吸收利用具有特异性。结合N、P元素含量及N∶P值的大小可知,研究区芦苇生长受到N、P共同限制,且更易受N元素的限制。     

伊犁河谷苦豆子C、N、P含量变化及化学计量特征

研究苦豆子不同器官中碳、氮、磷元素的化学计量特征的季节变化有助于深入了解该植物蔓延的生态学机制。系统分析了伊犁河谷苦豆子根、茎、叶的碳(C)、氮(N)、磷(P)化学计量特征及其季节动态变化。结果表明∶苦豆子C、N、P含量均值分别为391.40、13.17、1.51mg/g,C∶N、N∶P、C∶P均值分别为45.61、8.52、326.38。苦豆子根、茎、叶在整个生长季内C、N、P均值含量变化一致,为叶茎根。在生态化学计量特征的分析中规律则不同,C含量随着生长时期的增加而增加,N和P的含量则随着生长时期的增加而减少;苦豆子根系中的C、N、P含量有随着深度变化而递减的趋势;器官间的差异性说明植物在不同生长时期,各器官对C、N、P的吸收利用具有特异性。植物叶片中C、N、P含量和N∶P普遍较低,苦豆子生长受N、P的共同限制,更容易受到N元素的限制。     

Carbon dynamics in the deciduous broadleaf tree Erman's birch (Betula ermanii) at the subalpine treeline on Changbai Mountain,Northeast China

Premise of the Study

The growth limitation hypothesis (GLH) and carbon limitation hypothesis (CLH) are two dominant explanations for treeline formation. The GLH proposes that low temperature drives the treeline through constraining C sinks more than C sources, and it predicts that non‐structural carbohydrate (NSC) levels are static or increase with elevation. Although the GLH has received strong support globally for evergreen treelines, there is still no consensus for deciduous treelines, which experience great asynchrony between supply and demand throughout the year.

Methods

We investigated growth and the growing‐season C dynamics in a common deciduous species, Erman's birch (Betula ermanii), along an elevational gradient from the closed forest to the treeline on Changbai Mountain, Northeast China. Samples were collected from developing organs (leaves and twigs) and main storage organs (stems and roots) for NSC analysis.

Key Results

Tree growth decreased with increasing elevation, and NSC concentrations differed significantly among elevations, organs, and sampling times. In particular, NSC levels varied slightly during the growing season in leaves, peaked in the middle of the growing season in twigs and stems, and increased continuously throughout the growing season in roots. NSCs also tended to increase or vary slightly in developing organs but decreased significantly in mature organs with increasing elevation.

Conclusions

The decrease in NSCs with elevation in main storage organs indicates support for the CLH, while the increasing or static trends in new developing organs indicate support for the GLH. Our results suggest that the growth limitation theory may be less applicable to deciduous species' growth than to that of evergreen species.     

Seasonal biomass allocation in a boreal perennial grass (Phalaris arundinacea L.) under elevated temperature and CO2 with varying water regimes

The aim of this study was to analyze and model how biomass is allocated to the leaves, stems, and roots of perennial grass (reed canary grass, Phalaris arundinacea L., hereafter RCG) under elevated temperature (ET) (+approx. 3 °C) and CO₂ (approx. 700 μmol mol^?1) and with variable groundwater levels (high to low water levels) in a boreal environment. For this purpose, RCG plants were grown in environmentally controlled chambers over two growing seasons (April–September of 2009 and 2010), and the plant organ biomass (leaves, stems, and roots) was measured seven times over the entire growing season. The results showed that biomass production was mainly allocated to the leaves (LMF) and stems (SMF) early in the growing season, to the stems in the middle of the growing season, and to the roots (RMF) later in the growing season. Compared to ambient conditions, ET treatments increased LMF and SMF, and decreased RMF over the growing season under well-water conditions. Under low groundwater level, ET treatments decreased LMF and increased RMF throughout the growing season, and increased SMF in early periods and then decreased later in the growing season. CO₂ enrichment did not significantly affect the seasonal allocation pattern between plant organs. The effect of the groundwater level on biomass allocation was stronger than that of the climatic treatments. In conclusion, plant phenology controlled the seasonal course of biomass allocation in RCG and climatic treatments affected biomass allocation to each of the three plant organs, while the direction and extent of climate-related changes in biomass allocation depended on the availability of groundwater. The influence of groundwater level appeared to be crucial for the carbon gain regarding the production of RCG biomass for energy purpose and the concurrent sequestration of carbon in soils under changing climate in the mire sites used to cultivate RCG.     

华北石质山地侧柏人工林C、N、P生态化学计量特征的季节变化

以北京九龙山自然保护区幼龄侧柏人工林为研究对象,对其不同生长季节叶、枝、根(0—10 cm、10—20 cm土层)的碳(C)、氮(N)、磷(P)含量及其生态化学计量学特征进行了分析,深入探讨了生长季节与器官以及两因素交互作用对以上特征的影响,研究有助于理解植物各性状之间的相互作用以及植物生长过程中资源的利用和分配状况。结果表明:1)不同器官间C含量为414.97—461.58 g/kg,枝最大,根(0—10 cm)最小;N含量为6.57—14.28 g/kg,叶最大,枝最小;P含量为0.39—1.28 g/kg,叶最大,根(10—20 cm)最小;C∶N为31.76—70.98,枝最大,叶最小;C∶P为369.93—1099.20,根(10—20 cm)最大,叶最小;N∶P为9.21—23.81,根(0—10 cm)最大,枝最小。整个生长季节中侧柏各器官C含量最稳定,变异系数均小于7%;P含量变异性最大,变异系数均超过15%,N含量变异性介于两者之间;各器官中C∶N和N∶P较C∶P更为稳定,C、N与P具有较好的耦合协同性,C∶P和N∶P的变化主要取决于P的变化。2)器官对C、N、P含量及其化学计量关系均存在显著影响,生长季节对N和P含量存在显著影响,两者交互作用只对P含量存在显著影响,器官对侧柏C、N、P含量及其化学计量变异的贡献大于生长季节。3)侧柏各器官间C、N、P含量及其化学计量比相关性多数未达到显著性水平,仅有叶与枝中的P及C∶P显著相关,说明侧柏器官分化过程中各器官对元素的吸收利用具有特异性。侧柏叶片N∶P14,说明生长季节里幼龄侧柏人工林更多受到N限制。     

Contribution of Ectomycorrhizal Fungi to Cadmium Uptake of Poplars and Willows from a Heavily Polluted Soil

Phytoextraction has been proposed in recent years as an environmentally and cost-efficient treatment technique for the remediation of heavy-metal contaminated sites. In particular, plants that are fast growing, metal accumulating, and economically interesting, such as sunflowers or trees, recently became more important in research on phytoextraction. Heavy metal uptake of trees can be strongly influenced by ectomycorrhizal fungi. We investigated the possibility of enhancing phytoextraction of Cd by willows (Salix viminalis) and poplars (Populus canadensis) in association with three well known ectomycorrhizal fungi (Hebeloma crustuliniforme, Paxillus involutus and Pisolithus tinctorius). A pot experiment was conducted using Cd polluted soil from a contaminated site. Four replicates of each combination of fungus and tree species, and controls without fungal inoculum, were set up. After a growth period of 11 weeks, yields and Cd concentrations in roots, stems, and leaves were measured. In addition, the total Cd uptake, the transfer to roots, and the translocation to stems and leaves were calculated. The association of P. canadensis with P. involutus led to a highly significant increase of Cd concentrations, in particular in the leaves, which contained 2.74 ± 0.34 mg Cd per kg dry matter. Compared to the control this is an enhancement of nearly 100%. The fungi also significantly enhanced the translocation from the roots to the leaves, leading to a concentration ratio (leaves/roots) of 0.32 ± 0.06 compared to 0.20 ± 0.02 of the control plants. Additionally, P. involutus significantly enhanced the total Cd extraction by P. canadensis. Similar effects were not observed by other fungi or in association with S. viminalis.     

The response of plants to elevated CO2

Tree saplings, two groups of three species from each of two deciduous tree communities, were grown in competition at three CO₂ concentrations and two light levels. After one growing season, biomass was measured to assess the effect of CO₂ on community structure, and nitrogen and phosphorus concentrations were measured for leaves, stems, and roots of all trees. Gas-exchange measurements were made on the same species grown under the same CO₂ concentrations.Photosynthetic capacity (rate of photosynthesis at saturating CO₂ and light) tended to decline as CO₂ concentration increased, but differences were not statistically significant. Stomatal conductance declined significantly as CO₂ increased. Nitrogen and phosphorus concentrations generally declined as CO₂ increased, but there were some unexpected patterns in roots and stems. CO₂ concentration did not significantly affect the overall growth of either community after one season, but the relative biomass of each species changed in a complex way, depending on CO₂ light level, and community.     

西藏毛茛属二新种

该文描述了发现自中国西藏南部的毛茛科毛茛属二新种,即隆子毛茛(Ranunculus longziensis W.T. Wang)和单根毛茛(R. uniradicatus W. T. Wang)。隆子毛茛(新种)与睫毛毛茛(R. densiciliatus W. T.Wang)在亲缘关系上甚为相近,两者不同的是此新种(隆子毛茛)的茎无毛,叶也无毛,基生叶不分裂,多具5条脉,茎生叶呈披针状条形;单根毛茛(新种)与聂拉木毛茛(R. nyalamensis W. T. Wang)在体态上稍微相似,两者不同的是此新种(单根毛茛)为一年生草本植物,只具一条须根,茎无毛,花瓣呈狭倒卵形,子房被短柔毛。     

Occurrence of fungal endophytes in cultivars ofTriticum aestivum in South Africa

Fungal endophytes were isolated from leaves, roots and stems of four wheat cultivars and a breeding line at three different sampling dates during the 1993 growing season. Of the 55 different fungal taxa encountered, 19 were present at relative importance values of more than 5%. No cultivar-related differences in the assembleges of endophytes were observed.Phoma glomerata was not restricted to only one tissue type, whereasAlternaria alternata, basidiomycete sp. 1,Pleospora herbarum andEpicoccum nigrum occurred primarily in the leaves, andFusarium avenaceum was extremely frequent in roots. In general, colonization by endophytes increased with the age of the plants. Most endophytes were isolated from wheat leaves. Successional colonization of a given tissue type was quantitative rather than qualitative, with a given fungal taxon increasing or decreasing over the period sampled, rather than replacing the fungi initially encountered.Present address: Téra d'Sott 5, CH-6949, Comano, Switzerland.     

Influence of root temperature on uptake and accumulation of Ni and Co in potato

The impact of root temperature on Ni and Co concentration and accumulation has been studied in organs (roots, tubers, stems and leaves) of Solanum tuberosum L. var. Spunta plants. The response of foliar- and root-urease activity was also determined under the same conditions. Four different polyethylene plastic covers were employed (T1: transparent; T2: white; T3: coextruded black+white; T4: black), using uncovered plants as control (T0). The different treatments had a significant effect on mean root zone temperatures (T0 = 16 °C, T1 = 20 °C, T2 = 23 °C, T3 = 27 °C and T4 = 30 °C) and induced a significantly different response in the Ni and Co distribution in potato organs, since T3 (27 °C) gave higher concentrations of Ni in roots, leaves and tubers. The T1 (20 °C) registered the greatest Co concentration in leaves and roots, while T3 gave higher Co concentrations in tubers. The tubers proved to be the organs with the highest biomass and also the highest Co and Ni accumulation. With respect to the response of the urease activity as Ni-bioindicator, the root urease activity was higher in T1, whereas the leaf urease activity was higher in T3 and T4, coinciding with higher concentrations of leaf Ni. It is necessary to ascertain the relevance and control of the thermal regime of the soil to optimize the phytoextraction (phytoremediation) of elements.     

NaCl处理对西伯利亚白刺幼苗生长及离子平衡的影响

以1年生西伯利亚白刺水培幼苗为材料,研究了不同浓度NaCl(0、200、400mmol·L~(-1))处理对幼苗生长及不同器官(根、茎、叶)中Na~+、K~+、Ca~(2+)、Mg~(2+)的吸收、运输与分配的影响,探讨西伯利亚白刺的盐适应机制。结果表明:(1)200mmol·L~(-1) NaCl处理促进了西伯利亚白刺幼苗的生长及叶片肉质化程度,400mmol·L-1 NaCl处理显著抑制其生长。(2)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根、茎、叶中Na~+含量显著增加,且叶中Na~+含量显著高于茎和根中;根系中K~+含量显著增加;根、茎、叶中Ca~(2+)、Mg~(2+)含量在200mmol·L~(-1) NaCl处理下保持平稳或上升,而在400mmol·L-1 NaCl处理下显著下降。(3)各器官中K~+/Na~+、Ca~(2+)/Na~+和Mg~(2+)/Na~+比值总体随NaCl处理浓度的升高呈下降趋势,且根部离子比值始终高于叶片和茎。(4)随着NaCl处理浓度的升高,西伯利亚白刺幼苗根-茎SK,Na显著下降,而根-茎SCa,Na、SMg,Na及茎-叶SK,Na、SCa,Na、SMg,Na逐渐提高。研究发现,西伯利亚白刺的盐适应机制主要是通过植株的补偿生长效应及叶片对Na~+的聚积作用实现的,同时也与根系对K~+的扣留及茎叶对K~+、Ca~(2+)、Mg~(2+)选择性运输能力增强有关。     

Morphological and anatomical variations ofCajanus cajan (Linn.) huth raised in cadmium-rich soil

Different concentrations of cadmium in the growing media affected morphological parameters ofCajanus cajan. Over time, the amount of increase in shoot and root lengths, number of branches and leaves per plant, single and total leaf areas, and dry mass of leaves, was significantly lower for treated plants compared with controls. The root-shoot length ratio, which varied little over time, was relatively low for the treated plants. Although dry mass of both stems and roots increased, the rates were considerably low under Cd stress. The root-shoot dry mass ratio in the controls was highest during flowering and lowest in the post-flowering stage, but continually declined over time for the stressed plants. Compared with the controls, treated plants had fewer pods, with the number decreasing as the Cd concentration increased. Cd content was greater in roots than in stems or leaves, and leaves had greater amounts than did stems at higher doses. For all plants, the width and density of vessel elements and the length of fibers in the wood of stems and roots increased with plant age. However, the rate of increase was generally lower in the treated plants, the difference being more pronounced with higher doses of Cd. This indicated a reduced ascent of sap and, hence, less available water for tissues in treated plants.     

不同铅水平下紫茎泽兰细胞内铅的分布和化学形态的分析

该研究运用差速离心法和化学试剂逐步提取法,分析了重金属铅在紫茎泽兰亚细胞内的分布和主要化学形态。结果表明:随着Pb浓度的升高,紫茎泽兰的叶、根、茎中各亚细胞组分Pb含量逐渐增加;紫茎泽兰中的Pb在叶片分布于可溶性部分和细胞壁中,两者占总量的75.34%~84.63%;茎也主要分布于可溶性部分和细胞壁中,占总量的36.10%~57.14%和20.07%~36.52%;而在根中则富集于细胞壁和可溶性部分,分别占39.2%~49.78%和28.27%~37.62%,其他细胞器中的Pb含量均较少。紫茎泽兰叶中的Pb以盐酸提取态和水提取态为主,两者占总量的58.74%~73.04%;茎中的Pb以醋酸提取态和氯化钠提取态为主;而根中的Pb则以醋酸提取态和盐酸提取态占优势,两者占总量的39.15%~52.91%。     

Winter feeding behaviour of European rabbits in a temperate zone habitat

Herbivores living in seasonal environments commonly have to deal with reduced food availability and quality during the winter season. The present study investigated how European rabbits Oryctolagus cuniculus living in a grassland habitat adapt their feeding behaviour to cope with this situation. Both adult and subadult animals markedly increased their feeding rates throughout the course of the winter, with the rates in subadults being generally higher. Nevertheless, both age classes showed a significant decline in body mass throughout the winter averaging 22.3% of the autumn mass in subadult and 9.7% in adult animals. In late winter, an increase in the faecal sand content was found, indicating that the animals were feeding on ground-level plant parts. Measurements of nitrogen content of (1) grass leaves and stems and (2) ground-level sprouts and roots demonstrated a decrease in the food quality of grass leaves and stems from early to late winter. In contrast, the nitrogen content of roots and ground-level sprouts remained stable. It can be speculated that the animals increasingly switched to ground-level plant parts as alternative food in the course of the winter in order to satisfy their needs for a sufficient source of nitrogen.     

Sulphate can induce differential expression of thioglucoside glucohydrolases (myrosinases)

Thioglucoside glucohydrolase (EC 3.2.3.1; myrosinase) hydrolyses glucosinolates and thereby liberates glucose and sulphur and nitrogen compounds. To examine the hypothesis that the myrosinase-glucosinolate system is influenced by environmental factors, the effect of sulphate on the expression of myrosinases was examined. On examining different plant organs at various stages, it was observed that sulphate induces a differential expression of myrosinase polypeptides in plants ofSinapis alba L. (white mustard). Specific myrosinase polypeptides, dependent on sulphate in the growth medium, were detected on immunoblots. Without sulphate a maximum of three polypeptides was detected in buds, two in cotyledons and one in stems and roots. In plants cultured on medium with sulphate up to four polypeptides could be observed in cotyledons, five polypeptides in buds, two in stems and one in roots. Expression of myrosinases was, in general, high in plants cultured on a medium supplemented with sulphate. In floweringS. alba plants, sulphate-starved plants showed a higher expression of myrosinase in cotyledons and stems compared to plants fed with sulphate. Sulphate-fed plants had a high expression in inflorescences and roots. The organ- and time-specific induction of the myrosinase expression is discussed in relation to sulphate metabolism and availability of sulphate under normal conditions of cultivation and in relation to protection of Brassicaceae species. This is the first evidence for a specific induction of individual myrosinase proteins.