Growth of three cattail (<Emphasis Type="Italic">Typha</Emphasis>) taxa in response to elevated CO<Subscript>2</Subscript>

The establishment of non-native species and the increase in atmospheric CO₂, in combination, have the ability to alter current ecosystems. Previous studies have shown that invasive species tend to respond more strongly to CO₂ than natives, but these comparisons have been of different and unrelated species. To assess how response to CO₂ might be related to invasiveness per se, we compared a native (Typha latifolia) with a congeneric invasive (Typha angustifolia), as well as their hybrid (T. × glauca). All three taxa are common components of wetland vegetation, often occurring in near monocultures. An open-top chamber experiment was used to examine the effects of elevated and ambient CO₂ concentrations on the three taxa. All three increased rhizome biomass by 40% in elevated CO₂. Although the absolute increase did not differ among taxa, the invasive T. angustifolia had a much higher proportional response in biomass and photosynthetic rate (45 and 40% respectively). The weaker response of the two larger taxa native T. latifolia (16 and 2%) and hybrid T. × glauca (−4% and −1%) was possibly driven by soil nutrient deficiency, such that they were not able to benefit from increased CO₂. However, under low nutrients the smaller species T. angustifolia may become more a problematic invader in the future.     

Typha glauca Godron and its parental plants in Poland: taxonomic characteristics

Natural interspecific hybridization between Typha latifolia L. and Typha angustifolia L. was analyzed by morpho-anatomical and molecular methods to determine whether the hybrid Typha glauca Godr. is present in Poland and to identify the best diagnostic traits for its identification. Eighty-three samples of the Typha species were collected. Nine random amplified polymorphic DNA (RAPD) primers provided 12 fragments specific for T. angustifolia and eight fragments specific for T. latifolia. DNA of all sampled individuals was analyzed with 20 diagnostic RAPD markers. The morpho-anatomical variability of T. glauca F₁ was found to be quite similar to that observed in parental plants. All of the 41 traits examined in the hybrids overlapped with those observed in the parents, however, the hybrids were visibly closer to T. angustifolia than to T. latifolia. The most discriminate characteristics were the length and pedicel width, as well as the epidermal cell thickness located above vascular bundles in leaf blades. Moreover, preliminary observations of seed sculpture showed that the length of testa cells could also be used to identify T. glauca. Clusters and the hybrid index (for molecular and morphological data) were highly coincident and support the hybridization hypothesis.     

Habitat preferences of cattail species and hybrids (Typha spp.) in eastern Canada

Interspecific hybridization is widespread in plants and is an important evolutionary process. Hybrids may be fitter than their parental species, at least under some environmental conditions, and this may lead to partitioning of taxa by habitat. In eastern Canada, two cattail species (Typha latifolia and Typha angustifolia) and their hybrid (Typha x glauca) are known to have become increasingly widespread in recent decades, although their habitat preferences and patterns of co-existence at the local scale are not well known. We quantified the occurrence of these three taxa in three different habitat types (high traffic, low traffic, and ‘natural’) at 40 different sites along a sampling route of approximately 2000 km in eastern Canada. There were no significant overall associations between habitat type and taxon, although intraspecific comparisons among sites showed that the hybrid was most likely to grow in high traffic (highly disturbed) sites. In addition, pairwise comparisons revealed significant independence of T. latifolia and T. angustifolia, although the hybrid was equally likely to co-exist with either of its parental species. The presence of the three taxa in several habitats, including highly disturbed roadside areas, is consistent with their increasingly invasive tendencies.     

Isozyme gene markers in the dioecious species Asparagus officinalis L.

Summary Extracts from phylloclads of Asparagus officinails were electrophoretically analyzed for isozyme polymorphism. Fourteen enzyme systems were examined using four buffer systems: seven enzymes (acid phosphatase, catalase, glutamate-oxaloacetate transaminase, isocitrate dehydrogenase, malate dehydrogenase, peroxidase, and 6-phosphogluconate dehydrogenase) exhibited clear and consistent banding patterns. Isozyme polymorphism was studied in seven pairs of male and female doubled haploids and in their male F₁s. Segregation of polymorphic loci was examined in the backcross progenies and was found to be consistent with a simple Mendelian inheritance in all cases, except for three anodical peroxidases, where two factors have been hypothesized. No linkage could be found between isozyme markers that were segregating in the same cross, but association was demonstrated between one malate dehydrogenase locus and the sex determining genes. The availability of isozyme markers may be useful in breeding and, in particular, the localization of one malate dehydrogenase locus on the sex chromosomes may be helpful in mapping the sex genes.     

Molecular genetic data reveal hybridization between Typha angustifolia and Typha latifolia across a broad spatial scale in eastern North America

A recent increase in the abundance of cattails (Typha spp.) in North American wetlands has been anecdotally linked with hybridization between Typha latifolia and Typha angustifolia. In this study, we used molecular genetic markers (microsatellites) to investigate whether the hybrid lineage (Typha × glauca) is restricted to The Great Lakes region, or exists across a much broader spatial scale. We also investigated the possibility of backcrossing and genetic introgression in natural populations. Parental species could be distinguished from one another based on the distribution of alleles at six microsatellite loci. Species identification based on genetic data corresponded well with species identifications based on leaf width, a key morphological trait that can distinguish the two parental species. We found that hybrids occur in Ontario, Quebec, New Brunswick, and Nova Scotia, but we did not detect hybrids in Maine. F₁s are more abundant than backcrossed or intercrossed hybrids, although we also found evidence of backcrossing, particularly in Ontario. This indicates that hybrids are fertile, and are therefore potential conduits of gene flow between the parental species. Further work is needed to determine whether T. × glauca is particularly successful in the Great Lakes region relative to other areas in which the two parental species co-exist, and to assess whether introgression may lead to increased invasiveness in the species complex.     

Intercontinental dispersal of Typha angustifolia and T. latifolia between Europe and North America has implications for Typha invasions

The full effects of biological invasions may be underestimated in many areas because of cryptogenic species, which are those that can be identified as neither native nor introduced. In North America, the cattails Typha latifolia, T. angustifolia, and their hybrid T. × glauca are increasingly aggressive invaders of wetlands. There is a widespread belief that T. latifolia is native to North America and T. angustifolia was introduced from Europe, although there has so far been little empirical support for the latter claim. We used microsatellite data and chloroplast DNA sequences to compare T. latifolia and T. angustifolia genotypes from eastern North America and Europe. In both species, our data revealed a high level of genetic similarity between North American and European populations that is indicative of relatively recent intercontinental dispersal. More specifically, the most likely scenario suggested by Approximate Bayesian Computation was an introduction of T. angustifolia from Europe to North America. We discuss the potential importance of our findings in the context of hybridization, novel genomes, and increasingly invasive behaviour in North American Typha spp.     

Plagiothcium laetum in Britain

Abstract

Variations in (1) banding patterns of peroxidase, acid phosphatase and esterase isozymes and (2) morphological characters, of two British and two Finnish populations of Sphagnum recurvum var. mucronatum are described. No links were found between the presence of specific isozyme bands and individual morphological characters, nor were the individual populations typified by particular bands. The results do present some evidence for the linking of certain morphological characters with environmental conditions and suggest that there may be a relationship between the complexity of banding patterns and the stability of site conditions.     

Identification of aneuploids in Nicotiana tabacum by isozyme banding patterns

A biochemical system was devised to identify aneuploids of Nicotiana tabacum. Leaf tissue from 6 nullihaploids, 4 nullisomics, and 10 monosomics was analyzed electrophoretically on slab acrylamide gels. The staining systems used were for peroxidase, esterase, superoxide dismutase, malate dehydrogenase, and glutamate oxaloacetate transaminase. Nullihaploids and nullisomics could be distinguished from each other and from haploid or disomic types by their unique isozyme banding patterns. The banding patterns of the monosomics closely resembled those of the disomic. Morphologically similar aneuploids from different populations had similar isozyme banding patterns.This paper represents research completed in partial fulfillment of the requirements for the Ph.D. degree by the senior author. The investigations reported in this paper (No. 81-3-119) are in connection with a project of the Kentucky Agricultural Experiment Station, and the paper is published with the approval of the Director.     

Vesicular arbuscular mycorrhizae in floating wetland mat communities dominated by Typha

Low levels of vesicular arbuscular mycorrhizae were present in floating mats dominated by clones of Typha angustifolia L., T. x glauca Godr., and T. latifolia L. Floating mats composed of rhizomes (underwater-ground stems with high starch accumulation), roots, decaying organic matter, and wind deposited soil, easily supported human activities. The majority of roots isolated from the root cores were connected to Typha rhizomes. Tests employing the gridline intersect method, intensity, spore counts and most probable number (MPN) were used to define the level of colonization. Mycorrhizal colonization from the T. angustifolia and T. x glauca clones averaged 4 to 5%, while the T. latifolia clone averaged 13%. When colonization was encountered, intensities varied from a high of 3.0 to a low of 0.4 on a sclae of 0 to 4. Although arbuscules were not found, abundant hyphae, vesicles and spores indicated that presumed facultative associations occurred between the vesicular arbuscular fungi and the indicated that presumed facultative associations plant communities found on floating mats. The mycorrhizal fungi identified from these communities in cluded Glomus albidum Walker & Rhodes, G. caledonium (Nicol. & Gerd.) Trappe & Gerdemann, G. etunicatum Becker & Gerdemann, and G. microcarpum Tul. & Tul. Spore counts ranged from 16 to 76 spores per gram dried organic soil. The recolonization ability of VAM propagules by way of a most probable number bioassay with maize yielded numbers that ranged from zero to 96 propagules per gram soil, with G. etunicatum the only species recovered.     

Three-trophic-level interactions in cattail hybrid zones

Plant-herbivore and herbivore-parasitoid wasp interactions were examined in three hybrid zones of the cattails Typha latifolia and T. angustifolia in south-eastern Michigan over a 2-year period. Patterns of resource use by two lepidopteran species of seed-eating herbivores were studied and herbivore densities sustained by the hybrid cattail T. x glauca and its parental species were determined. Densities of the commoner seed-eating lepidopteran, Lymnaecia phragmitella, were found to be highest in seed heads of both parental species and lowest in hybrid seed heads in zones of hybridization, thus supporting the hybrid resistance hypothesis of Fritz et al. (1994). Densities of the second herbivore, Dicymolomia julianalis, on the hybrid were lower than on the parental T. latifolia, but did not differ from the mean of the combined herbivore densities of the two parental species. D. julianalis in cattails appears to fit the additive hypothesis (Fritz et al. 1994). Parasitism of L. phragmitella by four species of parasitoid wasp, Itoplectis conquisitor (Ichneumonidae), Scambus hispae (Ichneumonidae), Macrocentrus delicatus (Braconidae), and Temelucha gracilipes (Ichneumonidae), was studied to determine if rates of parasitization by these natural enemics on the different cattails were similar to the patterns of plant exploitation exhibited by their hosts. Parasitism rates of L. phragmitella were significantly higher in larvae reared on hybrid cattails. This study reveals two different patterns of hybrid utilization by two very similar herbivores. Opposite patterns of plant utilization were found for the parasitoids compared with their host (L. phragmitella) in cattail hybrid zones.     

Use of Isoenzymes to Differentiate Growth Categories of Pericopsis Mooniana Trees

Leaf isoenzymes of Pericopsis mooniana from twenty-one trees at forest plantation were evaluated for their use in identification of elite trees among heterogeneous population. Trees were grouped morphologically, before leaf extracts were separated by one-dimensional polyacrylamide gel electrophoresis. Isoenzyme analysis were carried out for peroxidase, esterase, alcohol dehydrogenase, formate dehydrogenase, acid phosphatase, aspartate aminotransferase, isocitrate dehydrogenase, malate dehydrogenase, leucine aminopeptidase, phosphoglucoisomerase, phosphogluconate dehydrogenase, phosphoglucomutase, and shikimate dehydrogenase. From the thirteen enzymes studied only four gave distinct banding patterns. Level of significance of appearing particular band for each enzyme of a given category was investigated using χ²-test, followed by cluster analysis for categorization. The isozyme type A of formate dehydrogenase showed promising results that could be used for differentiating trees of categories investigated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Isozyme Variation and Genetic Diversity of the European Barley Powdery Mildew Population

Isozyme and virulence analyses of Erysiphe graminis bordei were performed with samples collected from different sites from nearly all over Europe. Isozymes and unspecific proteins extracted from conidia were separated by starch gel electrophoresis and isoelectric focusing, respectively, and the resulting isozyme banding patterns were compared with the corresponding virulence data. One isozyme phenotype prevailed in all samples. Only 7.9% of 280 isolates showed divergent banding patterns. Expected frequencies of isolates with divergent banding patterns were calculated for each subsample. In the Italian subsample, isolates with divergent banding patterns were significantly more frequent than expected. At the same time, isolates from Italy had significantly fewer virulence factors than those from N.W. Europe, indicating weaker selection by host resistance genes. It is suggested that isozyme uniformity in the homogeneous north-western European barley powdery mildew population has arisen from strong selection pressures for specific virulence genes. The direction of this selection, acting upon a mainly asexually reproducing population, has changed over space and time due to the introduction of new resistance genes, forcing local populations through bottlenecks. This may have led to random loss of genetic variation (genetic drift) in the barley powdery mildew gene pool.     

Ecophysiological responses to different forest patch type of two codominant tree seedlings

According to gap‐phase dynamics theory, forests can be divided into four distinct patch types: gap patch (G), building patch (B), mature patch (M), and degeneration patch (D). Varying light conditions across patch types are one of the most important factors affecting the coexistence of vegetation. Mechanisms of coexistence can be understood through detailed knowledge of ecophysiological responses of codominant tree seedlings to patch types. The following study was conducted to determine ecophysiological responses of Cyclobalanopsis glauca (an evergreen broad‐leaved species) and Bothrocaryum controversum (a deciduous broad‐leaved species) to four different patch types. During the gap‐phase dynamics, light intensity and the magnitude of change in the four different patches followed the order of: G > B > D > M. Both species had the greatest photosynthetic capacity in the G patch. Dry leaf mass per area (LMA), Chlorophyll a + b concentration (Chl), carotenoids (Car), and nitrogen content per area (N_a) all responded to changes in light across patch type, but B. controversum showed greater sensitivity and changes than C. glauca. From G to M patch, the maximal quantum efficiency of PSII (F_v/F_m) had a larger variation magnitude for B. controversum than for C. glauca. From G to M patch, B. controversum showed significant changes in gas exchange, while C. glauca showed only small changes. Ecophysiological trait partitioning of response to light in different patches provides a possible explanation of a coexistence mechanism.     

Genetic diversity in the top onion,Allium ×proliferum (Alliaceae), analysed by isozymes

Polymorphisms for six enzyme systems (GPI, IDH, PDG, PGM, SKD, and TPI) were analysed in the top onion,Allium ×proliferum. Five multilocus isozyme genotypes were found. The banding patterns of top onions were compared with those ofA. ×wakegi, A. cepa, A. fistulosum, A. altaicum, and artificial hybrids between these three species. One top onion type and one artificial hybrid had identical banding patterns. Shallots andA. altaicum, the wild progenitor ofA. fistulosum, cannot be distinguished from the common onion andA. fistulosum, respectively; these species are also potential contributors to the top onion's gene pool.     

Genetic variability for esterase enzyme in Onobrychis species

Summary Understanding polymorphism at the enzyme level is basic to its use in population and genetic studies. However, no such information is available on the variability among different sainfoin (Onobrychis) species. Therefore, our objective was to study the existence of genetic polymorphism for esterase in 17 Onobrychis species and three cultivars of O. viciifolia Scop. Three regions of banding were observed in all the materials tested, with the number of bands varying from 0 to 3, 3 to 14, and 1 to 2 bands in each of these zones, which have been designated EST1, EST2, and EST3 respectively. All the materials studied had unique banding patterns, the only common feature being that all of them, except one species, had isozyme 1. Identification was possible only for four species (O. iberica, O. kachetica, O. transcaucasica, and O. bieberstenii) and one cultivar (Nova) based on the banding patterns. Large diversity was evident from the wide range of percent similarity values (0%–79%). Subsequent studies should be directed in using these isozyme banding patterns as markers to the desirable agronomic and quality traits of different germplasm lines.This work was supported by USDA Specific Cooperative Agreement No. 58-7MN1-8-143 from the Plant Stress and Water Conservation Unit, USDA-ARS, Lubbock, Texas. Joint contribution of the Texas Tech University, Lubbock, Texas and the USDA-ARS. TTU Journal no. T-4-302     

Allelopathy as a mechanism for the invasion of <Emphasis Type="Italic">Typha angustifolia</Emphasis>

The direct competitive effects of exotic plants on natives are among the leading causes of plant extinctions worldwide. Allelopathy, one type of direct plant competition, has received relatively little research, particularly in aquatic and wetland systems, even though allelopathy can be a potent mechanism through which plant communities are structured. Typha angustifolia (narrow-leaved cattail) is an invasive exotic plant in North America that often forms monocultures in disturbed wetlands and is more invasive than native members of its genus. We tested whether T. angustifolia was allelopathic and whether it produced different biochemicals than a native congener by growing it with the native bulrush Bolboschoenus fluviatilis (river bulrush) in soil with and without activated carbon and by qualitatively and quantitatively comparing soluble phenolics produced in the roots of T. angustifolia and the native Typha latifolia (broad-leaved cattail). T. angustifolia had a strong allelopathic effect on B. fluviatilis, reducing the longest leaf length and root, shoot, and total biomass of B. fluviatilis. When the allelopathy of T. angustifolia was ameliorated by activated carbon, however, longest leaf length, ramet number, root biomass, shoot biomass, and total biomass of T. angustifolia were greatly reduced due to resource competition with B. fluviatilis. Furthermore, T. angustifolia produced different, but not more, soluble phenolics than T. latifolia suggesting that the identity of the phenolics is different between the two species rather than the concentrations. The allelopathic effects of T. angustifolia on a North American native wetland plant and its production of root biochemicals that appear to differ from those produced by a native congener are consistent with the possibility that T. angustifolia may use a novel allelochemical in its invasion of North American wetlands.     

BIOLOGICAL AND HISTORICAL FACTORS INFLUENCING GENETIC DIVERSITY IN THE SCUTELLARIA ANGUSTIFOLIA COMPLEX (LABIATAE)

Studies of genetic diversity at isozyme loci were used to examine the phylogenetic distribution of several frequently reported population-genetic parameters in a putatively monophyletic group of plant species, the Scutellaria angustifolia complex. The influence of taxon-specific differences in habitat preference, breeding system, degree of endemism, and phylogenetic relatedness was examined. Many characters of reproductive morphology traditionally used in phylogenetic inference vary with breeding system. To the extent that reproductive systems are conservative markers of phylogenetic relationships, one would expect the distribution of genetic variation to be similar in closely related taxa. Results showed that closely related taxa may exhibit very different genetic-diversity statistics and that distantly related taxa may exhibit very similar genetic-diversity statistics. This suggests that complex patterns of evolution of breeding systems and morphological characters have occurred in the ten taxa included in the Scutellaria angustifolia complex. Similarity in habitat is not associated with similarity in genetic diversity in this group of species.     

Genetic Diversity Among Iranian Isolates of Rhizoctonia solani Kühn Anastomosis Group1 Subgroups Based on Isozyme Analysis and Total Soluble Protein Pattern

Rhizoctonia solani is a destructive fungal pathogen with a wide host range. The R. solani complex species includes several divergent groups delimited by affinities for hyphal anastomosis. In this study, genetic variation among 20 isolates of R. solani anastomosis group 1 (AG1) subgroups (AG1‐IA and AG1‐IB) collected from Mâzandaran province, Iran, and standard isolates of these subgroups, was determined by isozyme analysis and total soluble protein profile. Mycelial protein pattern and isozyme analysis were studied using denaturing and non‐denaturing polyacrylamide gel electrophoresis, respectively. A total of 15 enzyme systems were tested, among which six enzymes including esterase, alkaline phosphatase, superoxide dismutase, octanol dehydrogenase, lactate dehydrogenase and mannitol dehydrogenase generated distinct and reproducible results. The soluble protein patterns were similar among the R. solani isolates examined; however, minor differences in banding pattern were observed between the two subgroups. In isozyme analysis, a total of 64 electrophoretic phenotypes were detected for all six enzymes used. Based on cluster analysis and similarity matrix, the fungal isolates were divided into two genetically distinct groups of I and II consistent with the previously reported AG1‐IA and AG1‐IB subgroups in AG1. Group I represented all isolates belonging to AG1‐IA subgroup, whereas group II represented all isolates belonging to AG1‐IB subgroup. Results from isozyme analysis suggest that the subgrouping concept within AGs is genetically based.     

Mating system analysis in a natural population of Acacia nilotica subspecies leiocarpa

The mating-system was investigated in a natural population of the tetraploid taxon Acacia nilotica ssp. leiocarpa using open-pollinated seeds from 15 families. Six-day-old germinated seeds were used for starch-gel electrophoresis. Three enzyme systems (ADH, EST-1, and 6PGD) were scored. Isozyme banding patterns and segregation of isozyme variants within families suggest that the species is an autotetraploid displaying tetrasomic inheritance. Estimates of single-locus (t_s=0.358) and multilocus (t_m=0.384) population outcrossing rates were homogeneous, and indicate substantial selfing in the population. Heterogeneity of outcrossing estimates among loci and families were marked, suggesting departure from the assumptions of the mixed-mating model. Implications of the result for the utilization of germplasm in tree-improvement programmes are noted.