ISSN / EISSN : 1916-2790 / 1916-2804
Published by: Canadian Science Publishing (10.1139)
Total articles ≅ 1,428
Latest articles in this journal
Botany pp 671-682; https://doi.org/10.1139/cjb-2021-0053
The Thomas Brook in the Annapolis Valley, Nova Scotia, was the focus of an Agriculture and Agri-Food Canada wastershed evaluation of beneficial management practices (WEBs) project from 2004–2008. The stream is impacted by human activities along its course, with residential influences and farming operations. The water quality in Thomas Brook was assessed in 2006, and the current study done in 2011–2012 used the same standard invertebrate metrics to measure water quality. This project also examined the prevalence of gut endosymbionts (trichomycetes) in aquatic invertebrates to determine whether water quality affects this community of obligate microorganisms in their hosts. The water quality was improved in Thomas Brook in 2011/2012 compared with that measured in the earlier study. There were 34 taxa of trichomycetes recorded in benthic insects in the stream, including two new species. The trichomycete community was rich in dipteran hosts (midges and black fly larvae), but the prevalence of gut fungi in ephemeropteran (mayfly) nymphs in the system was low, perhaps due to the impact of human activities on water quality.
Botany, Volume 99, pp 619-627; https://doi.org/10.1139/cjb-2021-0037
Swainsonine, an indolizidine alkaloid, is an α-mannosidase and mannosidase II inhibitor that alters glycoprotein processing and causes lysosomal storage disease. Swainsonine is the toxic principle in several plant species worldwide and causes severe toxicosis in livestock grazing these plants. All swainsonine-containing plant taxa investigated to date are associated with fungal symbionts that produce swainsonine. Among the swainsonine-containing convolvulaceous species, Ipomoea carnea Jacq. is associated with a seed-transmitted symbiont belonging to the fungal order Chaetothyriales. The nature of this association was unclear; therefore, this association was investigated further using microscopy. Macroscopic and microscopic data reported here demonstrate that the Chaetothyriales symbiont associated with I. carnea grows ectopically on the adaxial (upper) surface of leaves as lacy mycelia in plants that contain swainsonine and was not present on plants lacking swainsonine that were derived from fungicide-treated seeds. Hyphae were not observed on the surface of any other tissues including the abaxial (lower) leaf surface, petiole, and stem. Mycelia were not visible in internal tissues below the epidermis, and there did not appear to be any hyphal extensions within the fibrovascular bundles or stomata. Longitudinal and (or) cross sections of the stems or petioles did not show evidence of hyphae growing between cells. These results suggest an epibiotic growth habit of the Chaetothyriales symbiont in association with I. carnea.
Botany, Volume 99, pp 639-650; https://doi.org/10.1139/cjb-2021-0027
La présente étude porte sur la nature des rhizobia associés aux légumineuses du genre Hippocrepis qui compte une dizaine d’espèces en Algérie et pour laquelle très peu de travaux ont été jusqu’ici consacrés. Les résultats de nos investigations qui ont portés sur 26 plants représentant 8 espèces de ce genre et provenant de 17 localités du nord et du sud du pays révèlent que tous les plants étaient nodulés et fixateurs d’azote, ce qui indique que les 8 espèces identifiées sont capables d’établir une symbiose efficiente avec les rhizobia présents dans les sols qui les supportent. Le séquençage du gène de l’ARN 16S des 26 souches de rhizobia isolées et authentifiées par des tests de nodulation au laboratoire permet de les assigner à 16 espèces de rhizobia réparties sur 5 genres: Ensifer, Mesorhizobium, Bradyrhizobium, Rhizobium et Neorhizobium avec une prédominance des représentants des genres Ensifer et Mesorhizobium. Les résultats de cette étude qui est la première dédiée spécifiquement au genre Hippocrepis indiquent que la symbiose à rhizobia et la capacité d’utiliser, par ce biais, l’azote atmosphérique sont communes chez les représentants de ce genre en Algérie, ils révèlent aussi la grande diversité des rhizobia qui sont associés à ce genre.
Botany, Volume 99, pp 609-618; https://doi.org/10.1139/cjb-2020-0235
The alpine vegetation of Europe and the Caucasus has experienced substantial changes due to climate warming and reduced grazing. Exposed ridge communities, such as alpine heaths, are presumed to be less vulnerable to such processes. Herein, we analyze long-term dynamics (over 37 years) of an alpine lichen heath in the Teberda State Biosphere Reserve, Karachaevo-Cherkessian Republic, Russia. We counted the shoots of all vascular plants present on permanent plots. Autocorrelated linear regressions, a non-metric multidimensional scaling ordination, and a fourth-corner analysis were applied to characterize the relationships between shoot numbers, climate variables (temperatures and precipitation), functional traits, and species strategies. Nine species, including dominant Festuca ovina L. and Antennaria dioica (L.) Gaertn., increased their abundances, whereas Carex spp. were observed to decrease. The overall dynamics were mainly driven by increasing mean temperatures during the growing season (July and August). None of the changes observed in the selected traits were correlated with increasing or decreasing numbers of species; however, some traits (plant height, specific root length, specific leaf area, and leaf carbon content) were potentially associated with climate variables. The observed dynamics suggested an overall increase in the abundance of herbaceous plants. Generally, our results support “greening” effects in tundra and alpine biomes.
Botany, Volume 99, pp 601-608; https://doi.org/10.1139/cjb-2021-0039
Beyond strong inference that most of the 2600 known species of Arecaceae produce diaspores with an underdeveloped embryo and therefore have morphological dormancy (MD) or morphophysiological dormancy (MPD), little is known about the specific dormancy class or sub-class and how dormancy-break occurs under ecological conditions. Here, we found that mature seeds of Trachycarpus fortunei (Hook.) H.Wendl. collected at the time of natural dispersal had an underdeveloped embryo that was 10% of total seed length. No diaspores germinated over a wide range of temperatures in either light or darkness. Cold stratification at 4 °C for one, two, and three months or treatment with 100, 500, and 1000 ppm gibberellic acid (GA3) improved germination percentages, with three months cold stratification or 1000 ppm GA3 resulting in highest germination. The embryo grew inside the seeds during cold stratification; however, warm stratification did not improve germination. Therefore, seeds of T. fortunei have intermediate complex MPD. Cold-stratified seeds that were moved to spring conditions (night and day temperatures of 15 and 20 °C, respectively) had cotyledonary petiole (CP) elongated, but leaves developed only when the CP elongated seeds were moved to summer temperatures (night and day temperatures of 25 and 30 °C, respectively), suggesting the presence of shoot dormancy. The seedlings are remote-tubular type. This is the first report for Arecaceae indicating the presence of complex MPD.
Botany, Volume 99, pp 665-670; https://doi.org/10.1139/cjb-2020-0163
Nasa is the most diverse genus among the family Loasaceae and it is mainly distributed in Peru. Most species of this genus are microendemics, with distributions restricted to very specific locations; such is the case of Nasa colanii Dostert & Weigend. This species — previously only known from the type collected in 1978 from the Amazonas region of Peru — lacks information about its biology and ecology. To improve our understanding of the reproductive biology and pollination ecology of N. colanii, we observed flower development and insect floral visits in a cloud forest in the Amazonas region. The flowers of N. colanii are nectariferous and protandrous. The typical stamen movement to the flower center of the subfamily Loasoideae appears to be autonomous. Only well-developed (elongated) pistils showed positive stigmatic receptivity to 3% hydrogen peroxide. Syrphid flies (Baccha sp.) and small beetles (Baridinae spp. and Alticini sp.) were the only observed flower visitors. The syrphid flies visited the flower and foraged for pollen, whereas the small beetles were found already in the flowers and seemingly used it as a shelter. Results suggest that N. colanii might be adapted to fly pollination.
Botany, Volume 99, pp 651-664; https://doi.org/10.1139/cjb-2020-0140
As habitats change, species with higher intraspecific variation have more resources to adapt. Medicinal plants in the Himalayas are increasingly threatened by climate change and other anthropogenic influences. The intraspecific variation within and among 17 populations of the high-elevation herb Trillium govanianum Wall. ex D.Don was studied as an indicator of adaptability. The variation in 19 traits of population structure, morphology, and phytochemistry was assessed across habitats that varied in elevation (2452–3432 m a.s.l.), aspect, latitude (30.1–31.7°N), and arboreal community. The morphology and population structure were conserved among populations but varied among regions. The populations in the lower elevation mixed forests of Tirthan Valley produced smaller rhizomes but larger plant densities, such that plant biomass per square metre was conserved. The phytochemistry varied among regions and populations within regions, indicating significant variation among habitats. The aboveground morphology of the species masks considerable variations in belowground morphology and phytochemistry. The observed variations can help the species to adapt to the changing environmental conditions by provoking a functional response.
Botany, Volume 99, pp 629-638; https://doi.org/10.1139/cjb-2020-0229
Gametophytes of the fern Ceratopteris richardii Brongn. are either male or hermaphrodite. The presence of hermaphrodite-secreted antheridiogen influences gametophytes to develop as male (induction), while its absence leads to hermaphrodite development. Males require the continued presence of antheridiogen to remain male. Removal of males from antheridiogen leads to sex change (conversion) of males to hermaphrodites. The density of hermaphrodites that males were exposed to and the amount of time males were exposed to antheridiogen were experimentally manipulated to determine whether conversion time was affected. Analysis of covariance was employed with male size serving as a covariate. The results suggest that males continuously sample the neighborhood for information regarding the density of hermaphrodites by perceiving hermaphrodite-secreted antheridiogen, then use this information to determine whether to convert to hermaphrodite. Larger males converted faster than smaller males, suggesting a potential for smaller males to remain male once larger males convert. Conversion time was longer in males grown in higher densities of hermaphrodites and shorter in males exposed to antheridiogen for a longer time, suggesting that males increase sensitivity to antheridiogen with higher doses but decrease sensitivity as they age. It is thought that such “decision making” is important for C. richardii populations to maintain beneficial sex ratios.
Botany, Volume 99, pp 589-600; https://doi.org/10.1139/cjb-2021-0023
The cherry spruce rust caused by Thekopsora areolata (Fr.) Magnus results in significant losses in spruce seed production in the forest industry. The pathogen is present in Asia and Europe but absent from North America where it has been considered as a potential threat and listed as a quarantine organism by the United States Department of Agriculture. A comprehensive list and in-depth information regarding the alternate hosts of this pathogen are important for conducting epidemiological studies and for optimal disease control. Prunus padus L. is the main alternate host reported for T. areolata. In this study, we investigated the susceptibility of domestic and exotic Prunus spp. and other potential alternate host-plant species native to Scandinavia to T. areolata infection through a field survey and aeciospore inoculation experiments in the greenhouse and laboratory. No new susceptible species were found. In Sweden, a new record of Prunus grayana Maxim. with low susceptibility to T. areolata was found. In addition, we updated the list of currently confirmed alternate hosts of T. areolata according to field observations and inoculation results. Prunus padus and Prunus serotina Ehrh., as well as their hybrids and subspecies of Prunus padus, are highly susceptible, while Prunus depressa Pursh, Prunus grayana, Prunus spinosa L., and Prunus tenella Batsch are considered slightly susceptible.
Changes in climate are leading to modifications in the timing of seasonal events such as migrations and flowering. Erythronium americanum (trout lily) can break bud early in response to warming, but changes to its growing season may be limited by early shade from canopy trees and frost. I experimentally assessed the impact of shade and frost on senescence in E. americanum and descriptively monitored the response of E. americanum to vernal air and soil temperatures in a garden setting. Early shade did not affect the timing of senescence. Experimental exposure to frost resulted in increased leaf damage, earlier senescence, and greater corm death than in control plants. Despite ten days in which the air temperature dropped below freezing, there was no evidence of leaf damage in the field. These results suggest that early shade from canopy trees will not hasten the end of the future growing season for E. americanum, but that late frost could bring about early senescence if that frost is sufficiently hard.