Ecotypic differentiation of response to enhanced CO2 and temperature levels in Arabidopsis thaliana

Five ecotypes of Arabidopsis thaliana, from widely dispersed origins, were grown under combinations of ambient and elevated atmospheric CO₂ concentrations and ambient and elevated temperatures within solardomes. Total above-ground plant biomass was measured when the majority of plants across all ecotypes and treatments had formed seed pods. There were substantial differences in biomass between the ecotypes across all treatments. Temperature had no effect on biomass whilst CO₂ had a significant effect both alone and in interaction with ecotype. The CO₂ x ecotype interaction was mostly due to the enhancement of a single ecotype from the Cape Verde Islands.     

The Origin and Genetic Status of Insular Caprines in the Eastern Mediterranean: A Case Study of Free-Ranging Goats (Capra aegagrus cretica) on Crete

The history and species status of free-ranging goats inhabiting the Eastern Mediterranean islands is discussed with reference to morphometric, archaeological and genetic findings. A case study on the free-ranging goats on Crete (Capra aegagrus cretica) is presented. The phenotype of the Cretan goat resembles that of the wild bezoar goat (C. aegagrus). However, the mitochondrial DNA of cytochrome b and d-loop sequences shows affinity with domestic goats. It has been suggested that the Cretan goat represents a feral animal that was introduced onto the island during the 6th millennium b.c. as a primitive domestic, and has retained the wild morphotype but has undergone significant genetic change. An alternative explanation, and the one that is proposed here, is that the goat was introduced onto the island in wild form and released as a food source. Subsequent introgressions with domestic animals, especially ewes, have influenced its genotype. These conclusions are applicable to other free-living goats and sheep which inhabit islands in the Eastern Mediterranean.     

Genetic diversity of dodder (<Emphasis Type="Italic">Cuscuta</Emphasis> spp.) collected from commercial cranberry production as revealed in the<Emphasis Type="Italic">trn</Emphasis>L (UAA) intron

Swamp dodder (Cuscuta gronovii) is a parasitic plant detrimental to cranberries. Observation of emergence of dodder seeds collected from a cultivated cranberry bog in Massachusetts revealed 2 or more peak emergence times during 4 consecutive growing seasons. Molecular methods were used to investigate genetic variation among the emerging dodder seedlings. On emergence, dodder seedlings were collected and analyzed for DNA sequence diversity in thetrnL (UAA) intron, a noncoding region of chloroplast DNA. DNA sequence analysis of 87 seedlings collected during the 1999 and 2000 growing seasons revealed the presence of 2 dodder ecotypes, designated A and B. Comparative DNA sequence analysis indicated that in thetrnL (UAA) intron, the sequence of ecotype A is identical to that ofCuscuta gronovii, whereas the sequence of ecotype B is closest to that ofCuscuta attenuata (99.3% sequence identity; 293 bases considered). ABg/II restriction enzyme cut site was identified that distinguished between thetrnL (UAA) introns of ecotypes A and B. Restriction fragment length polymorphism (RFLP) was used to analyze the sequences of 100 seedlings collected during the growing seasons of 2001 and 2002. Only 10 of the 187 samples were ecotype A, all of which emerged on or before May 7 in the growing seasons. Therefore, the predominant dodder haplotype found in this study may be a close relative ofC. attenuata and notC. gronovii, the common species found in cranberry bogs.     

Effect of Pb on leaf antioxidant enzyme activities and ultrastructure of the two ecotypes of <Emphasis Type="Italic">Sedum alfredii</Emphasis> Hance

Hydroponic experiments were conducted to study the effect of Pb on growth, leaf antioxidant enzyme activities, and ultrastructure of the accumulating ecotype (AE) and non-accumulating ecotype (NAE) of Sedum alfredii Hance. AE was found to be more tolerant to excessive Pb levels in growth medium. Concentrations of Pb in the shoots of the AE were 1.98 times higher than those in the NAE when 0.2 mM Pb was supplied. Both chlorophyll a and b did not decrease significantly in AE plants after Pb treatment, while a significant decrease was noted in chlorophyll a and b of NAE plants treated with Pb concentrations greater than 0.05 mM. The results showed that activities of superoxide dismutase (SOD) and catalase (CAT) were elevated in the leaves of AE under Pb stress. However in NAE, Pb-caused enhancement was noticed only in the activity of SOD while activity of CAT was declined as compared to the control plants. With increased Pb level, malondialdehyde (MDA) content increased significantly in both ecotypes of S. alfredii, indicating that Pb toxicity led to lipid peroxidation and membrane damage, but MDA content in the leaves of NAE was always higher than in AE plants. The ultrastructural analysis of the spongy mesophyll cells revealed that excessive Pb concentrations obviously damaged the cell membrane, chloroplasts, and mitochondria of both the ecotypes but damage was more severe in NAE. Although growth, leaf physiology, and ultrastructure of both the ecotypes were affected by Pb treatment, deleterious effects were more pronounced in NAE. This text was submitted by the authors in English.     

The effect of Chinese tallow tree (Sapium sebiferum) ecotype on soil–plant system carbon and nitrogen processes

The EICA hypothesis predicts that shifts in allocation of invasive plants give rise to higher growth rates and lower herbivore defense levels in their introduced range than conspecifics in their native range. These changes in traits of invasive plants may also affect ecosystem processes. We conducted an outdoor pot experiment with Chinese tallow tree (Sapium sebiferum, Euphorbiaceae) seedlings from its native (Jiangsu, China, native ecotype) and introduced ranges (Texas, USA, invasive ecotype) to compare their relative performances in its native range and to examine ecotype effects on soil processes with and without fertilization. Consistent with predictions, plant (shoot and root) mass was significantly greater and leaf defoliation tended to be higher, while the root:shoot ratio was lower for the invasive ecotype relative to the native ecotype. Seasonal amounts of soil–plant system CO₂ and N₂O emissions were higher for the invasive ecotype than for the native ecotype. Soil respiration rates and N₂O emission increases from fertilization were also greater for the invasive ecotype than for the native ecotype, while shoot-specific respiration rates (g CO₂–C g⁻¹ C day⁻¹) did not differ between ecotypes. Further, soil inorganic N (ammonium and nitrate) was higher, but soil total N was lower for soils with the invasive ecotype than soils with the native ecotype. Compared with native ecotypes, therefore, invasive ecotypes may have developed a competition advantage in accelerating soil processes and promoting more nitrogen uptake through soil–plant direct interaction. The results of this study suggest that soil and ecosystem processes accelerated by variation in traits of invasive plants may have implications for their invasiveness.     

Variable compatibility of clonedAlnus glutinosa ecotypes against ineffectiveFrankia strains

Nodulation tests onin-vitro propagated clones ofAlnus glutinosa ecotypes (forest ecotype, pioneer ecotype) withFrankia strains originating from both ecotypes indicated differences in host-plant compatibility. Inoculated plants of the pioneer ecotype clone were not infected by strains, that were unable to fix nitrogen in pure culture. Nodulation could only be induced on the clone of the forest ecotype, but no nitrogen-fixing activity could be detected. Ultra-structural observations of the nodules by SEM and TEM indicated that ineffectivity of these strains was correlated with the lack of vesicles in the infected cells. Cells were only filled with hyphae: neither sporangia nor vesicles could be detected. In contrast, effective nodules could be obtained on both alder clones after inoculation with an effective strain, showing normal development of vesicle clusters in infected cells. In pure culture the ineffective strains produced no vesicles; sporangia were found only during early stage of growth. The results demonstrate the existence ofFrankia strains which were either non-infective or ineffective on different clones ofAlnus glutinosa.     

Cellular and subcellular compartmentation of Ni in the Eurasian serpentine plants Alyssum bracteatum, Alyssum murale (Brassicaceae) and Cleome heratensis (Capparaceae)

This study investigated the cellular and subcellular compartmentation of Ni in the Eurasian serpentine species Alyssum murale, Alyssum bracteatum and Cleome heratensis and a non-serpentine population of A. murale (as a control) grown in hydroponic culture. Plant growth responses and Ni uptake clearly revealed the higher Ni tolerance of serpentine plants than the non-serpentine plants. Serpentine A. murale and A. bracteatum grew better at elevated (0.01 mM) Ni in the nutrient solution, supporting the view that the Ni hyperaccumulators have a higher requirement for Ni than normal plants. Low shoot Ni content of C. heratensis in response to the high Ni treatments indicated that this species employs an avoidance strategy for Ni tolerance. Energy-dispersive X-ray microanalysis showed that Ni was highly concentrated in the cell walls and cell lumen, most likely the vacuoles, of leaf epidermis of A. murale and A. bracteatum rather than in the mesophyll cells. EDX spectra from leaves of the non-serpentine A. murale suggested that Ni accumulated in both epidermal and mesophyll cells but not in the epidermal cell walls. Growth reduction and Ni toxicity in plants of the non-serpentine A. murale could be due to accumulation of Ni in the lumen of leaf mesophyll cells. Our data suggest that cellular and subcellular compartmentation are both possible mechanisms for Ni tolerance employed by the serpentine A. murale and A. bracteatum.     

Cd Hyperaccumulative Characteristics of Australia Ecotype Solanum Nigrum L. and Its Implication in Screening Hyperaccumulator

A pot culture experiment was used to determine the differences in uptake characteristics of a cadmium hyperaccumulator Solanum nigrum L. discovered in China, an ecotype from Melbourne, Australia and a non-hyperaccumulator Solanum melogena. Australian ecotype was not significantly different to the China ecotype. In particular, Cd concentration in leaves and shoots of S. nigrum collected from Australia were 166.0 and 146.3 mg kg^?1 respectively when 20 mg kg^?1 Cd spiked, and were not significantly different to the ecotype imported from China which had 109.8 and 85.3 mg kg^?1 respectively, in the stems and leaves. In contrast, the tolerance of the eggplant to Cd was significantly less than the two S. nigrum ecotypes. Although some morphological properties of S. nigrum collected from Australia were different from that of the plants collected from China, Cd hyperaccumulator characteristics of two ecotypes were similar. The results suggested that the tolerance and uptake of Cd may be a constitutive trait of this species.     

Respiration for maintenance and growth inReynoutria japonica ecotypes from different altitudes on Mt Fuji

Respiration for maintenance and growth ofReynoutria japonica ecotypes from altitudes of 700 and 2420 m on Mt Fuji were measured in two controlled thermal conditions. The maintenance respiration of the high-altitude ecotype at both 15 and 25°C was significantly (1.7-fold) higher than that of the low-altitude ecotype, whereas growth respiration was independent of both ecotype and temperature. The temperature coefficient (Q₁₀) of the maintenance respiration was about 1.9 in both ecotypes. The results show that there is ecotypic differentiation in the performance of maintenance respiration. It is suggested that the high maintenance respiration of the high-altitudeR. japonica ecotype is advantageous in severe upland environments but disadvantageous in a warm lowland climate in terms of carbon economy.     

Fractionation and Electrophoretic Patterns of Storage Proteins of Ebenus cretica. A preliminary Survey as a Tool in Taxonomy

Seed storage proteins of Ebenus cretica were fractionated to albumins, globulins, prolamins and glutelins according to their solubility in water, 0.5 M NaCl solution, 55 % propanol-2 and 0.125 M sodium borate (pH 9.0) containing 0.5 % SDS (sodium dodecyl sulfate) solution, respectively. Glutelins consist of the major (about 81 %) fraction of the total extracted proteins. Analysis by SDS-PAGE revealed that the total extracted protein patterns from different racemes of the same plant were similar, while those from seeds of different plants were different. In addition, distinct differences were observed within protein patterns of alkaline extractable glutelin fractions and salt soluble globulin fractions. In E. cretica four ecotypes (A – D) were distinguished by SDS-PAGE of total extracted seed proteins. The last method was more simple and rapid than others and was suggested for screening analysis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic transformation of Arabidopsis thaliana zygotic embryos and identification of critical parameters influencing transformation efficiency.

Summary An efficient procedure for Agrobacterium-mediated transformation of zygotic embryos derived from three different Arabidopsis thaliana ecotypes has been developed. This procedure yielded an average transformation rate of 76% for ecotype C24, and 15–20% for ecotypes Landsberg-erecta and Columbia. A critical step for optimal transformation was the preculture of embryos on a phytohormone-containing medium. Light and electron microscopical studies showed that, during preculture, procambium cells of embryos became highly susceptible to Agrobacterium infection. Transformed cells developed calli and regenerated shoots within 4–5 weeks of culture. A total of 1500 fertile transgenic plants were regenerated. In regenerated plants the presence of inserted DNA was verified by genomic Southern blot analysis, assays of enzymatic activities of reporter genes (neomycin phosphotransferase II and -glucuronidase) as well as by genetic segregation tests. R1 progenies of 45 randomly chosen transformed lines and 150 independent regenerants did not show any somaclonal variations as ascertained by both morphological and cytological criteria. Short duration (7–8 weeks), high efficiency, reproducibility and low frequency of somaclonal variation makes the zygotic embryo transformation particularly well-suited for T-DNA tagging mutagenesis.     

Plant regeneration from callus cultures in two ecotypes of reed (Phragmites communis Trinius)

Summary Different ecotypes of reed (Phragmites communis Trinius) provide an ideal resource for studies on plant environmental adaptations and presence of genes relating to stress resistance. Dune reed is a drought-tolerant reed ecotype growing in the desert regions of north-west China. In this work, in vitro culture systems of dune reed and local swamp reed (as control) were established by optimizing the culture conditions for each of them. Bright yellow calluses were induced on a Murashige and Skoog medium containing 4.5 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 5.4 μM naphthaleneacetic acid and 2.2μM benzyladenine. Benzyladenine promoted callus induction, but was not required for callus maintenance. Four types of callus have been identified from each of the reed ecotypes. Two types of callus, i.e. type A (formed normal green shoots) and type C (formed albino plants), were both found as embryogenic calluses. The optimal concentrations of 2,4-D to maintain embryogenic callus were 2.3–4.5 μM for dune reed and 9.0–13.5 μM for swap reed. Plant regeneration was achieved from types A and C callus in a hormone-free medium. The embryogenic calluses of swamp reed have been maintained for over 2 yr and still retain their strong embryogenic potential; however, those of dune reed gradually lost their embryogenic potential after only 7 mo. of culture. Regenerated plants from the two reed ecotypes showed, after a growth season, similar morphology and the same chromosome number (2n=8x=96, octoploid) as the wild plants.     

A new,pathogen-inducible gene of Arabidopsis is expressed in an ecotype-specific manner

In this study we describe a novel gene, which was isolated in an attempt to search for specific plant resistance genes of Arabidopsis against isolates of the phytopathogenic bacterium Xanthomonas campestris pv. campestris. The gene was cloned by differential screening of a genomic library of the Xcc 750-resistant ecotype Col-0, using cDNA populations derived from ecotype Col-0 and the Xcc 750-susceptible ecotype Oy-0. The isolated gene, CXc750, is differentially expressed in ecotypes of Arabidopsis thaliana. In addition, although highly expressed in uninfected plants, gene expression increases in response to pathogen attack. CXc750 potentially codes for a small, basic protein of about 10 kDa. The predicted protein product contains a potential signal leader peptide at the amino-terminal end but no ER retention sequence and no further transmembrane domain. This indicates that the gene product is transported to other compartments or out of the cell.The possible function of CXc750 as a member of the plant defense response system is discussed.     

CHARACTERIZATION OF TWO CHLORELLA VULGARIS (CHLOROPHYCEAE) STRAINS ISOLATED FROM WASTEWATER OXIDATION PONDS1

We report here on the characterization and isolation of two ecotypes of Chlorella vulgaris Beyerinck that coexist in wastewater reservoirs. One ecotype (C1) contains high amounts of chlorophyll b, is capable of autotrophic growth, and can utilize only a few organic solutes for growth. The second ecotype (C2) contains low amounts of chlorophyll b, requires vitamin B₁₂, and can support its growth with a broad range of organic compounds. Of the two ecotypes, the latter showed slower growth rates when light was the sole source of energy. Cells of C2-type Chlorella attained higher photosynthetic activities than C1-type cells at saturating irradiances. However, their low chlorophyll b content and lower light utilization efficiency suggest that C2-type Chlorella contains relatively low amounts of light-harvesting antennae, a disadvantage in severely light-limited ecosystems like wastewater reservoirs. We hypothesize that the two Chlorella types coexist by adopting different lifestyles: C1-type cells rely largely on their photosynthetic potential for energy conservation and growth, whereas C2-type cells may exploit their heterotrophic properties for this purpose.     

四种生态型芦苇叶中离子分布对生境的生理适应

采用X射线微区分析技术 ,测定了 4种生态型芦苇 (Phragmitesaustralis (CaV .)Trin .exSteud .)叶的表皮泡状细胞、叶肉细胞和叶脉维管束鞘细胞离子的含量。结果表明 :沼泽芦苇的鞘细胞内 ,K 、Na 、Ca2 、Mg2 和Cl-分布均较叶肉细胞和泡状细胞高。沙丘芦苇的泡状细胞中Ca2 分布较叶肉细胞和鞘细胞高 ,而Mg2 在其叶肉细胞 ,以及K 、Na 和Cl- 在其鞘细胞内分布均较高。在轻度盐化草甸芦苇的叶肉细胞内分布较多的Na 和Mg2 ,而在鞘细胞内K 、Ca2 和Cl- 的分布均较叶肉细胞和泡状细胞为高。重度盐化草甸芦苇的泡状细胞内Na 和Mg2 的分布较多 ;同样 ,在叶肉细胞中K 、Ca2 和Cl- 的分布也较多。最后 ,讨论了上述各种离子在不同生态型芦苇叶内分布的状况 ,以及与其环境适应的生理意义。     

Experimental ecology of Dryas octopetala ecotypes

Summary Growth, survival and reproduction of adult plants from three reciprocally-transplanted populations of Dryas octopetala were followed over a seven year period, from 1979 to 1986. The two most different ecotypes, from snowbed and fellfield environments, were strongly selected against in extreme foreign environments via differential growth, survival, and reproduction. The more phenotypically-plastic ecotype from the snowbed experienced rapid, early mortality on the fellfield, prior to morphological adjustment, but no mortality in the last five years of the experiment. The less plastic fellfield ecotype showed no mortality for the first three years followed by a steady decline in numbers for the next four years. The ecotypic difference in plasticity may account for the contrasting mortality patterns. A population of plants with intermediate morphology was intermediate in fitness in extreme environments, but showed no superiority in its home site, suggesting that it is not a locally-adapted population. Natural selection maintains genetic differences between snowbed and fellfield populations in the face of gene flow. However, based on the response of intermediates, there appear to be limits to the degree to which selection can fine-tune adaptation along environmental gradients.     

四种生态型芦苇叶中离子分布对生境的生理适应

采用X射线微区分析技术,测定了4种生态型芦苇(Phragmites australis (CaV.) Trin. exSteud.)叶的表皮泡状细胞、叶肉细胞和叶脉维管束鞘细胞离子的含量.结果表明:沼泽芦苇的鞘细胞内,K+、Na+、Ca2+、Mg2+和Cl-分布均较叶肉细胞和泡状细胞高.沙丘芦苇的泡状细胞中Ca2+分布较叶肉细胞和鞘细胞高,而Mg2+在其叶肉细胞,以及K+、Na+和Cl-在其鞘细胞内分布均较高.在轻度盐化草甸芦苇的叶肉细胞内分布较多的Na+和Mg2+,而在鞘细胞内K+、Ca2+ 和Cl-的分布均较叶肉细胞和泡状细胞为高.重度盐化草甸芦苇的泡状细胞内Na+和Mg2+的分布较多;同样,在叶肉细胞中K+、Ca2+和Cl-的分布也较多.最后,讨论了上述各种离子在不同生态型芦苇叶内分布的状况, 以及与其环境适应的生理意义.     

Asymmetric impacts of two herbivore ecotypes on similar host plants

1. Ecotypes may arise following allopatric separation from source populations. The simultaneous transfer of an exotic plant to a novel environment, along with its stenophagous herbivore, may complicate more traditional patterns of divergence from the plant and insect source populations. 2. The present study evaluated herbivory effects by two Cyrtobagous salviniae ecotypes on two species of Salvinia: the larger S. molesta and the smaller S. minima. Evaluations were based on relative growth rates, biomass production, coverage, and nutrient cycling in a series of complementary and comparative laboratory and outdoor tank experiments. 3. In general, the experiment results indicated that the smaller Florida ecotype of C. salviniae impacted both Salvinia species more than the larger Brazil ecotype. Herbivory, especially by the Florida ecotype, also improved water quality and accelerated nutrient cycling by increasing the rates of litterfall from the standing crops of salvinia. 4. The smaller size of the Florida ecotype may be adaptive by allowing maximal exploitation of host plants via internal larval feeding, which presumably reduces predation risk while increasing damage to the plant. These findings provide support for relying on the suppressive effects of the Florida ecotype in Florida, rather than introducing the Brazil ecotype to counter new infestations of S. molesta.     

Plant regeneration from mesophyll-protoplasts of four different ecotypes and two marker lines from Arabidopsis thaliana using a unique protocol

A protocol for obtaining regenerated fertile plants from mesophyll protoplasts of four ecotypes (Col C24, Per-1, Bur-0, Landsberg erecta) and two marker lines (M4 and M10) of Ardbidopsis thaliana is described. The different lines showed plating efficiencies between 1.0 and 3.9% using Nitsch medium or this medium supplemented with coconut water. For the differentiation of callus into normal shoots a single shoot regeneration medium was applicable to all ecotypes, but depending on the line other regeneration media showed to be more suitable. The results indicated that the protoplast culture procedure is applicable, with minor modifications, to all tested genotypes but the most suitable shoot regeneration medium should be established for each A. thaliana line.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - BAP 6-benzyl-aminopurine - IAA indole-3-acetic acid - IPA isopentenyladenine - IPAR isopentenyladenosine - MES 2-[N Morpholino]ethanesulfonic acid - MS Murashige and Skoog - NAA naphthaleneacetic acid     

Genetic similarity among Arabidopsis thaliana ecotypes estimated by DNA sequence comparison

DNA polymorphisms among Arabidopsis thaliana ecotypes are widely used as genetic markers in map-based cloning strategies. New PCR-based molecular markers do not only facilitate molecular mapping, but can also be used to obtain reliable sequence information for cladistic analyses. We have used CAPS (cleaved amplified polymorphic sequences) markers and a direct sequencing strategy to estimate genetic similarity among eighteen Arabidopsis ecotypes. Sequences at four loci, two from the nuclear and two from a non-nuclaar genome, were analysed. For each ecotype more than 1000pb of sequence information was obtained, and genetic similarity was calculated from a total of 35 polymorphic sites using a character-based approach. Divergence ranged from zero up to 50 discordant characters among the 72 characters defined by the polymorphisms. Separate calculations based on the nuclear and the non-nuclear sequences were performed and revealed a number of common features, including the existence of small clusters of very closely related ecotypes separated from each other by extensive sequence divergence. Our results provide information useful especially to investigators setting up crosses for chromosome landing strategies.