2016
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Item Patterns of thermotolerance, chlorophyll fluorescence, and heat shock gene expression vary among four Boechera species and Arabidopsis thaliana(Canadian Science Publishing, 2016-09-19) Halter, Gillian; Simonetti, Nicole; Suguitan, Cristy; Helm, Kenneth; Soroksky, Jessica; Waters, Elizabeth R.Thermotolerance is a property of all organisms, but due to their sessile nature, this trait is particularly important in plants. Basal thermotolerance is based on inherent tolerance to heat stress. Acquired thermotolerance is attained through stress-induced gene expression, often of those genes encoding heat shock proteins (HSPs). Both basal and acquired thermotolerance have been extensively studied in model species such as A. thaliana but much less is known about thermotolerance in wild plant species. The aims of this study are to examine the basal and acquired thermotolerance of four species of Boechera, and of A. thaliana. Four species of Boechera native to California were collected and used for this study: B. arcuata, B. californica, B. depauperata and B. perennans. Seedlings were exposed to both basal and acquired heat stress and then monitored for leaf damage, chlorophyll fluorescence, and gene expression of HsfA3, Hsp101 and four sHSP genes. Analysis of organismal responses to heat stress demonstrated that all four Boechera species are more thermotolerant than is A. thaliana. Further we found that he species with the highest thermotolerance is B. depauperata.Item The effect of soil inoculants on seed germination of native and invasive species(Canadian Science Publishing, 2016-12-05) Balshor, Bailey; Garrambone, Matt; Austin, Paige; Balazs, Kathleen R; Weihe, Claudia; Martiny, Jennifer B.H.; Huxman, Travis E.; McCollum, Johannah Reed; Kimball, SarahSuccessful re-introduction of native species through ecological restoration requires understanding the complex process of seed germination. Soil microbes play an important role in promoting native establishment, and are often added to restoration sites during seed sowing. We tested the role of soil and lab-grown bacterial inoculants on germination timing and percent germination for nineteen species of plants commonly found in coastal California. Each species exhibited a different response to inoculant treatments, but overall time-to-germination was longer and percent germination was lower with soil inoculant compared to control or other treatments. The invasive species in our study had the highest percent germination of all species and germinated faster than all native shrubs. Germination timing was negatively correlated with percent germination and with seed weight. Our results suggest that lab grown inoculant and chemical treatment are effective at increasing germination in some native species, while soil inoculant is not. Given differences in germination timing between native and invasive species, restoration practitioners could consider using herbicide to treat areas seeded with native shrubs immediately following germination of invasive species without harming most natives, although germination timing and herbicides need further study in relation to microbial effects on seed germination.Item Syntrichia norvegica Shoots Exhibit a Complex Inducible Response to Desiccation: separating the effects of Rate of Drying and Water Content(Canadian Science Publishing, 2016-11-19) Stark, Lloyd R.; Greenwood, Joshua L.; Slate, Mandy L.; Brinda, John C.Plants in the moss genus Syntrichia are considered to be constitutively desiccation tolerant (DT) â able to tolerate a rapid drying event without incurring significant damage upon rehydration. However, few workers have considered the separate effects of rate of drying and water content and incorporated fully dehardened (to DT) plants in the experiments. Plants of S. norvegica were cultured under conditions of suprasaturation and adult shoots were exposed to a range of drying rates and equilibrating relative humidities, rehydrated and assessed for chlorophyll fluorescence and regeneration potential. Adult shoots exhibited severe damage across all drying rates when equilibrated at RHsItem DOES AVIAN GUT PASSAGE FAVOUR SEED GERMINATION OF WOODY SPECIES OF THE CHACO SERRANO WOODLAND IN ARGENTINA?(Canadian Science Publishing, 2016-12-15) Díaz Vélez, María Celeste; Ferreras, Ana Elisa; Silva, Wesley Rodrigues; Galetto, LeonardoFrugivorous birds are key dispersal agents of many plant species and also may facilitate seed germination after gut-passage. However, the general effects of gut-passage on seed germination are still not clear, with positive, negative and neutral effects reported on seed germination. We evaluated seed germination of seven bird-dispersed plant species of the Chaco Serrano Woodland in C贸rdoba, Argentina: Celtis ehrenbergiana, Condalia spp., Lantana camara, Lithraea molleoides, Lycium cestroides, Schinus fasciculatus and Zanthoxylum coco. We compared germination percentages and germination speed among seeds ingested by birds, manually extracted seeds, and seeds from intact fruits in order to understand which mechanisms are acting on bird gut-passed seeds. For six plant species, the action of frugivorous birds increased seed germination percentages and provides faster germination, either through scarification, deinhibition, or through combined mechanisms. Our results contribute to better understand the mechanisms acting on bird gut-passed seeds. Also, we show the pivotal role that frugivorous birds exert on the seed germination of native woody plant species in the threatened ecosystem of Chaco Serrano Woodland.Item COINOCULATION WITH AN ARBUSCULAR MYCORRHIZAL FUNGUS AND A PHOSPHATE SOLUBILIZING FUNGUS PROMOTES PLANT GROWTH AND PHOSPHATE UPTAKE OF AVOCADO PLANTLETS AT NURSERY(Canadian Science Publishing, 2016-12-05) Tamayo-Velez, Alvaro; Osorio, Nelson WalterAn experiment was conducted to evaluate the effects of individual and dual with the phosphate solubilizing fungus Mortierella sp. and the arbuscular mycorrhizal fungus Rhizoglomus fasciculatum on plant phosphate uptake and growth of avocado (Persea americana Mill.) plantlets cv. Hass at the nursery. A completely randomized design was used. Treatments consisted of individual and combined inoculations with R. fasciculatum and Mortierella sp. at two concentrations (106 and 108 CFU mL-1) and an uninoculated control. The plant height, shoot dry weight, and shoot phosphate uptake were significantly higher with the co-inoculation with both fungi than with individual inoculation or uninoculated control plants. The colonization of fine roots with both fungi decreased when both were coinoculated in comparison to when they were individually inoculated, which suggest that these fungi compete for root space. Despite this competition, the dual inoculation showed that both fungi had additive effects on plant performance. Thus, shoot phosphate in mycorrhizal plantlets was significantly higher when Mortierella sp. was co-inoculated at both concentrations as compared to individual and uninoculated control plants (mycorrhizal-free).Item Trabeculae and Al-accumulation in the wood cells of Melastomataceae species from Brazilian savanna.(Canadian Science Publishing, 2016-10-19) Milanez, Camilla Rozindo Dias; Marcati, Carmen Regina; Machado, Silvia RodriguesMelastomataceae is an important component of the Brazilian Cerrado flora inhabiting different environments from those with well-drained soil to swamp soil sites. Several members of this family are recognized as aluminum (Al)-accumulating. We studied the wood anatomy of six species of Melastomataceae (Miconia albicans, M. fallax, M. chamissois, M. ligustroides, Microlepis oleaefolia, Rhynchanthera dichotoma), growing in different environments of Cerrado, exploring the occurrence of trabeculae and Al-accumulation sites. We processed the material following usual techniques in wood anatomy and histochemistry. We used chrome azurol-S spot-test in fresh material to detect Al-accumulation. The common features were diffuse porosity, vessel elements with simple perforation plates and vestured pits, abundant parenchyma-like fiber bands and septate fibers, axial parenchyma scanty to vasicentric, and heterocellular rays. Presence of trabeculae in vessel elements, septa in parenchyma cells and aluminum in the G-layer of the gelatinous fiber walls, in the septa of fibers, in cambial initials and derivatives cell walls, and in the vacuole of ray cells are the first record for Melastomataceae. The results of this study indicate an additional role for gelatinous fibers in Al-accumulation and offer a new perspective on the Al-compartmentalization in the wood cells from Cerrado species.Item The Death Cap mushroom (Amanita phalloides) moves to a native tree in Victoria, British Columbia(Canadian Science Publishing, 2016-10-25) Berch, Shannon M.; Kroeger, Paul; Finston, TerrieAmanita phalloides (Vaill. ex Fr.) Link, the Death Cap mushroom, is an invasive ectomycorrhizal fungus in North America that was inadvertently introduced from Europe. Death Cap mushrooms are highly toxic and have caused three recorded poisonings in British Columbia, including one recent death. In British Columbia, these mushrooms fruit mostly in urban environments in the greater Vancouver and Victoria areas under planted exotic broadleaf trees. In California, A. phalloides was demonstrated to also form ectomycorrhizas with a native oak species. Here we report that A. phalloides forms ectomycorrhizas with Quercus garryana, BCâ s only native species of oak, and can fruit in association with this tree host. If Death Cap mushrooms spread in Q. garryana habitat, the risk for serious mushroom poisoning will increase and mushroom harvesters, the medical community, and park managers need to be aware of this increased risk.Item Relation of antiglycation activity of leaves of 8 traditionally used wild blueberry species (Vaccinium L.) from northern Canada and Europe to phytochemistry(Canadian Science Publishing, 2016-10-06) Ferrier, Jonathan; Saleem, Ammar; Djeffal, Sabrina; Schlarb, James; Haddad, Pierre S.; Balick, Michael J; Cuerrier, Alain; Arnason, John T.Blueberry leaves (Vaccinium spp. L.) are used as a natural health product and traditional medicine for health maintenance in type 2 diabetes. In this study, 7 blueberry species available to northern communities in North America and one used by Lukomir Highlanders in Europe were assessed for phytochemical content and antidiabetic activity using an in vitro advanced glycation end product (antiglycation) assay. All Vaccinium spp were found to have potent antiglycation activity which was greater than that of the outgroup Gaylussacia sp. Inhibitory concentrations of Vaccinium spp leaf extracts varied from 4.1 to 79 Îźg/mL. The activity was correlated to phenolic content and eight phenolic metabolites were found to provide species markers. These species have potential for complementary dietary strategies for type-2 diabetics in northern communities.Item Auxin Cell Biology in Plant Pattern Formation(Canadian Science Publishing, 2016-12-01) Caragea, Adriana E.; Berleth, ThomasAuxin has always been implicated in a vast array of plant processes, but concomitant with a more detailed understanding of the cellular mechanisms underlying its biosynthesis, transport and perception, it has become increasingly clear that auxin has also instructive roles in plant pattern formation. Moreover, it turns out that in a multitude of instances, from early body axes establishment to organogenesis in shoot and root, plant tissue patterns owe their robust flexibility in part to feedback interactions involving auxin. Higher resolutions cell biology, molecular genetics and genomics as well as live imaging now are used together to define the parameters needed to generate more detailed and precise mathematical models of plant development.Item Genetic structure of the American ginseng (Panax quinquefolius L.) in Eastern Canada using reduced-representation high-throughput sequencing(Canadian Science Publishing, 2016-11-19) Joly, Simon; Archambault, Annie; Pellerin, Stéphanie; Nault, AndréeThe American ginseng (Panax quinquefolius L.) has been used for a wide range of medicinal purposes for more than 300 years and is at risk in most of its range due to harvesting in natural populations, herbivory, and habitat loss. Its genetic structure is largely unknown in the previously glaciated areas of Eastern Canada although such information could provide useful information for restoration strategies. We generated and analysed data from a reduced-representation high-throughput sequencing approach with a BAMOVA population model to partition the genetic variation within and among six natural populations of American ginseng in Eastern Canada. We found that an important and significant fraction of the genetic variation was structured among populations (ÎŚST = 42%; FST = 34%) at the geographical scale of the study (Item Comparative development of simple and compound leaves in the genus Cecropia(Canadian Science Publishing, 2016-09-05) Ogden, Michael Stephen; Lacroix, Christian R.Plants develop leaves that range from simple to compound in shape. The evolutionary divergence of simple and compound leaves has spurred research into identifying cellular and molecular processes involved in leaf shape determination. The roles of various genes and signalling pathways have been characterized in specifying leaf shape, however, few studies have investigated leaf primordium structure and shoot apex organization throughout development of both simple and compound leaves. Using Cecropia obtusa and Cecropia sciadophylla, two putatively closely related species bearing simple palmate and palmately-compound leaves, respectively, we compared the morphogenesis of leaves of both species at the shoot apex. Analysis of shoot apices using scanning electron microscopy yielded a non-significant difference in leaf primordium divergence angles and plastochron ratios, suggesting that divergence of the two leaf types occurred independently of primordium organization and growth rate at the shoot apex. Qualitative analysis of primordium initiation and morphogenesis revealed that both species share highly homologous development, as primordium structure and lobe/leaflet initiation sites are complementary in both leaf types. Our observations suggest a high degree of conserved ontogeny in the developmental pathways underlying the morphogenesis of simple palmate and palmately-compound leaves in these two species.Item Herbarium specimens as tools to assess the impact of large herbivores on plant species.(Canadian Science Publishing, 2016-10-10) Beauvais, Marie-Pierre; Pellerin, Stéphanie; Dubé, Jean; Lavoie, ClaudeHerbarium specimens can be used to reconstruct spatiotemporal changes in plant morphology caused by environmental pressures. The reliability of herbarium-derived data requires evaluation, because specimen collection is subject to biases. We used herbarium and field data to investigate the impact of large herbivore browsing on the size of a forb. White trillium (Trillium grandiflorum (Michaux) Salisbury) was studied because the impacts of white-tailed deer (Odocoileus virginianus Zimmermann) browsing on this species are well-known. A total of 692 herbarium specimens collected in Quebec (Canada) were used to evaluate leaf area. Leaf area values of herbarium specimens were compared to those of modern (2013, 2014) specimens collected in sites with > 8 deer per km2 or without deer. Flowering individuals in modern sites with deer had a significantly lower leaf area than herbarium specimens and modern specimens collected in sites without deer. The distribution of white trillium individuals in deer sites was also skewed towards plants with a smaller leaf area. Herbarium specimens may offer unique and inexpensive data, compared to methods traditionally used to assess the impacts of herbivores on plants such as exclosures or clipping experiments. Unfortunately, this rich data source is seriously jeopardized by the downtrend in specimen collecting.Item Root-endophytic fungi cause morphological and functional differences in Scots pine roots in contrast to ectomycorrhizal fungi(Canadian Science Publishing, 2016-09-13) Heinonsalo, Jussi; Buée, Marc; Vaario, Lu-MinEndophytic fungi and ectomycorrhizal fungi co-exist in the mycorrhizal root tips of boreal forest trees. However, very little is known about the functional role they play in their hostâ s biology. The activity of enzymes responsible for important biochemical processes is used to unravel the functional role of root-associated mycorrhizal fungi. However, enzyme activity is never studied in the presence of endophytic fungi in planta. The aims of the present study were to investigate the effect of Scots pine root-isolated fungal endophytes on the host plant root morphology, to determine their functional effect using host root-excreted enzyme activity measurements and to compare them to roots colonized by decomposer and ectomycorrhizal fungal strains and non-colonised Scots pine root tips. Our results show that endophytic fungi did not damage the pine roots in contrast to the decomposer fungi. The endophytic fungi penetrated the cortical cells of the host plant. The roots colonised by endophytic fungi produce different exo-enzymes compared to those produced by roots colonized by other fungal groups or non-colonized control root tips. Our results indicate that endophytic fungi are clearly a distinctive ecological group of fungi that have functional traits different from those of ectomycorrhizal and decomposer fungi.Item Seed dormancy in Camellia sinensis L. (Theaceae): Effects of cold-stratification and exogenous gibberellic acid application on germination(Canadian Science Publishing, 2016-08-28) Song, Danping; Jaganathan, Ganesh K.; Han, Yingying; Liu, BaolinThere are several different opinions about the presence of dormancy in tea (Camellia sinensis), but no strong evidence is available to conclude whether or not seeds are dormant. Freshly matured tea seeds collected from Hangzhou, China, at the natural dispersal time did not germinate in light at daily alternative temperature regimes of 10/15, 15/20, 20/25, 25/35ยบ C or at a constant temperature of 25ยบ C. Seeds were permeable to water and the embryos did not grow prior to radicle emergence, thus, the seeds have no physical, morphological or morphophysiological dormancy. When cold-stratified at 4ยบ C for 1, 2 and 3 months, 64, 88 and 93% of the seeds germinated respectively. Intact fresh seeds failed to germinate after treating with 0, 10, 500 and 1000 ppm GA3, whereas 3, 4, 61 and 86% of cracked seeds germinated respectively. Thus, the seeds have non-deep and intermediate physiological dormancy. Two-months cold-stratified seeds buried at 0, 1 and 5 cm soil depth in pots showed that seeds at 1 cm depth established significantly higher number of seedlings (PItem Revisiting the histological patterns of storage tissues: beyond the limits of gall-inducing taxa(Canadian Science Publishing, 2016-09-05) Ferreira, Bruno Garcia; Álvarez, Rafael; Avritzer, Sofia Caetano; Isaias, Rosy Mary SantosGall-inducing Aphididae may feed directly on phloem, while Eriophyidae and Nematoda feed on cells lining the gall chambers. We assume that a variation in structural complexity will occur within galls induced by each taxon, and that the complexity of the galls could be related with the types of storage tissue they have. Histological, histometric and histochemical analyses were used to compare six gall systems, which have different levels of complexity. Such levels are not taxon-related, even though eriophyid galls are usually simpler than nematode and aphid galls. The histological features of galls allowed the classification of storage tissues in three types: ‘typical nutritive tissues’ (TNT), ‘common storage tissues’ (CST), and ‘nutritive-like tissues’ (NLT). The TNT and NLT have cells with dense cytoplasm and a prominent nucleus. The CST cells are vacuolated, and may store starch and other energy-rich molecules, as do the NLT cells. In contrast to NLT or CST, the TNT serves as direct food source for gall inducers, and it is present in nematode and some eriophyid galls. NLTs may be present in some aphid galls, but are not the direct feeding site. The CST occurs on galls of all three inducing taxa.Item Taxonomic and cytogenetic studies in Opuntia ser. Armatae (Cactaceae)(Canadian Science Publishing, 2016-08-31) Las Peñas, Maria Laura; Oakley, Luis; Moreno, Natalia Cecilia; Bernardello, GabrielOpuntia series Armatae is evaluated considering morphological (vegetative, floral and carpological) and cytogenetical (diploid number, presence of heterochromatin and physical localization of ribosomal genes) features to shed light on their systematics and evolution. Three complexes (named O. elata, O. megapotamica and O. monacantha) are proposed to accommodate seven species according to the tepal, fruit, stigma and seed aril traits. Additional systematic conclusions include: 1. O. stenarthra, O. assumptionis, O. cognata and O. subsphaerocarpa are synonyms; 2. O. elata is a variable species with two varieties: var. cardiosperma and var. obovata; 3. O. rioplatense is a synonym of O. elata var. obovata and 4. O. megapotamica is a polymorphic species with two varieties (one newly described and a new combination). All species had small similar-sized symmetrical chromosomes and were tetraploid (2n=44), except for a population of O. arechavaletae and O. monacantha (2n=22). All showed one or two pairs with CMA+/DAPIâ NOR associated bands. The 18-5.8-26S rDNA loci seem to coincide with CMA+/DAPI-/NORs blocks. The number of 5S signals detected was proportional to the ploidy level of the species. A combination of cytogenetic and morphological features helped to differentiate the complexes, species, and varieties of Opuntia ser. Armatae.Item Geographic variation in floral traits is associated with environmental and genetic differences among populations of the mixed mating species Collinsia heterophylla (Plantaginaceae)(Canadian Science Publishing, 2016-08-17) Lankinen, Åsa; Madjidian, Josefin A.; Andersson, StefanRelatively few studies have investigated how geography, environmental factors and genetics affect floral trait variation. We used mixed-mating Collinsia heterophylla to explore variation in a suite of floral traits related to mating system in populations representing four geographic regions of California, USA, and relate this variation to geography, climatic factors and local site characteristics. We evaluated the environmental vs. genetic trait variability in the greenhouse. Stage of anther-stigma contact correlated positively with temperature, stage of stigma receptivity was negatively associated with vegetation cover and flower size differed among populations without any clear relation to environmental factors. Greenhouse data indicated heritability for stage of anther-stigma contact, flower size and time to flowering, and positive correlations between field and greenhouse for stage of stigma receptivity and flower size; however, stage of anther-stigma contact showed high degree of environmental influence. Stage of anther-stigma contact covaried positively with stage of stigma receptivity and flower size across maternal families, indicating genetic correlations between traits. In conclusion, phenotypic floral variation within mixed-mating C. heterophylla is mostly determined by a genetic component. Geography, environment and genetics affect traits differently, suggesting that ecological and evolutionary processes contribute to shaping variability in mating system-related traits.Item Corolla size and temporal displacement of flowering times among sympatric diploid and tetraploid highbush blueberry (Vaccinium corymbosum)(Canadian Science Publishing, 2016-10-06) Poster, Lauren S.; Handel, Steven N.; Smouse, Peter E.Polyploidy (whole-genome duplication) is common in vascular plants, but the modes of establishment and persistence, as well as the ecological consequences, of polyploidy remain vague. Highbush blueberry (Vaccinium corymbosum L.) is an ecologically and economically important understory shrub with an unclear species definition, coexisting in sympatric populations of diploid and tetraploid cytotypes. This study analyzes differences in bloom time between sympatric diploid and tetraploid V. corymbosum in natural populations, testing the potential for these cytotypes to interbreed and contributing to the formation and continuity of ploidy-level diversification within this species. Ploidal level was confirmed through DNA flow cytometry of sympatric plants from two populations in New Jersey, USA. Flower bloom date and corolla size were recorded over a three-year period. Diploid corollas were 32% smaller than tetraploid corollas, making them easily identifiable in the field. Ploidy accounted for 55-69% of the variation in bloom date, with diploids flowering about one week before tetraploids, and the remaining variation distributed among plants, among branches, and within branches. Notwithstanding these differences, there was modest overlap in flowering time between cytotypes, suggesting that cross-pollination is possible. This contributes evidence to the most current species definition of V. corymbosum as a single (mixed ploidy) species.Item Seedling recruitment in subalpine grassland forbs: Predicting field regeneration behaviour from lab germination responses(Canadian Science Publishing, 2016-06-19) Vandvik, Vigdis; Elven, Reidar; Töpper, JoachimEnvironmental cueing that restricts seed germination onto times and places where mortality risk is relatively low may have considerable selective advantage. The predictive power of lab germination responses for field regeneration behaviour is rarely tested. We screened 11 alpine grassland forbs for germination behaviours predictive of microsite and seasonal selectivity, and seed carry-over across years. The predictions were tested in a field experiment. Germination in the lab ranged from 0.05% to 67.9%, and was affected by light (5 species), temperature (6), fluctuating temperatures (4), moist chilling prior to germination (cold-stratification) (6), and dormancy-breaking by means of gibberellic acid (8). Seedling emergence in the field varied from 0.1% to 14.1%, and increased in low-competition microsites (bare-ground gaps and cut vegetation; 7 species), and showed seasonal timing (1 in autumn and 1 in spring), and seed carry-over across years (7). Lab germination responses successfully predicted microsite selectivity in the field and to some extent seed carry-over across years but not seasonal timing of germination. Gap-detecting species were generally small-seeded, low-growing, and found in unproductive habitats. Larger-seeded species germinated in all microsites but experienced increased mortality in high-competition microsites. Seed carry-over across years was lower in alpine specialists than in more widely-distributed species.Item Comparison of synandrium structure and development in three species from Myristicaceae(Canadian Science Publishing, 2016-08-27) Yang, Gui-Fang; Xu, Feng-XiaSpecies of Myristicaceae have diverse synandria morphology and structure, making them an interesting group for androecium evolution research. To clarify the morphology, structure, and origin of the synandrium, scanning electron microscopy and histology were performed on staminate flowers of Horsfieldia pandurifolia, H. tetratepala, and Myristica fragrans at different developmental stages. A whorl of stamen primordia was initiated rapidly around the margin of the floral apex in groups of two in H. pandurifolia and groups of three in M. fragrans. Each stamen primordium grew longitudinally, producing a pair of anther lobes and four microsporangia, accompanying one vascular bundle in H. pandurifolia and M. fragrans. In H. tetratepala, three stamen primordia groups were formed and each group with several anthers was supported by one vascular bundle, indicating a secondary increase of stamen. Three types of synandria origins were observedâ in M. fragrans, the central sterile column tissues originated from the elongate receptacle; in H. pandurifolia and H. tetratepala, they were derived from a combination of floral meristem and fused connectives, and a combination of receptacular tissue and stamen groups. The diverse origins of the central sterile column suggest that the synandrium develops differently and independently in different genera and species of Myristicaceae.