Showing papers in "Botany in 2012"
TL;DR: Fungal endophytes tested dramatically increased the percent of germination, improved EG and HTT values, and diminished wheat susceptibility to heat and drought as measured by fresh weight of seedlings when colonized by the most effective fungal endophyte.
Abstract: Seed germination is a critical life stage for plants survival and timely seedling establishment especially in stressful environments. We hypothesized that fungal endophytes would improve wheat seed...
133 citations
TL;DR: Recent advances in wood physiology, molecular phylogeny, and ultrastructure (chiefly scanning electron microscopy, SEM), as well as important new knowledge in traditional fields, provide the basis for a new vision of how wood evolves.
Abstract: Recent advances in wood physiology, molecular phylogeny, and ultrastructure (chiefly scanning electron microscopy, SEM), as well as important new knowledge in traditional fields, provide the basis ...
113 citations
TL;DR: The dominating forest management model in Canadian boreal forests, based on clear-cut harvesting and regeneration of short rotation even-aged stands, does not reflect the complexities of the disturbance-succession cycle observed in Cana- dian natural Boreal forests.
Abstract: Boreal forests have commonly been described as dominated by monospecific postfire stands that are reburnt well before other ecological process than those occurring immediately after fire can take p...
101 citations
TL;DR: Analytical, enzyme-linked, and colorimetric methods for analyzing GABA and related metabolites are discussed, and tracer evidence for the derivation of GABA from glutamate and its subsequent catabo- lism to succinic semialdehyde and either succinate or g-hydroxybutyrate is reviewed.
Abstract: γ-Aminobutyrate (GABA) is a ubiquitous four-C, nonprotein, amino acid that has been linked to stress, signaling, and storage in plants. In this paper, we discuss analytical, enzyme-linked, and colo...
82 citations
TL;DR: In a companion paper, this article discussed the origin of GABA from glutamamide and discussed its role in plant growth and survival in response to abiotic and biotic stresses, and showed that it is a ubiquitous nonprotein amino acid that accumulates in plants.
Abstract: γ-Aminobutyrate (GABA) is a ubiquitous nonprotein amino acid that accumulates in plants in response to abiotic and biotic stresses. In a companion paper, we discussed the origin of GABA from glutam...
73 citations
TL;DR: The results suggest the use of photosynthesizing BM, sep- arated into PFTs, in modelling ecosystem carbon exchange instead of using just total BM, which could result in higher NEE than larger GBM.
Abstract: We compared the amount and composition of different aboveground biomass (BM) fractions of four mires with their net ecosystem CO2 exchange (NEE) measured by eddy covariance. We found clear differences in response of green bi- omass (GBM) of plant functional types (PFTs) to water table (WT), which resulted in larger spatial variation in GBM within a mire than variation between mires. GBM varied between mires from 126 ± 7 to 336 ± 16 g·m -2 (mean ± SE), while within mire variation at largest was from 157 ± 17 to 488 ± 20 g·m -2 (mean ± SE). GBM of dominant PFTs appeared to be better in explaining the peak growing season NEE than the total BM or GBM of a mire. The differences in photosyn- thetic capacity between PTFs had a major role, and thus a smaller GBM with different species composition could result in higher NEE than larger GBM. Vascular plant GBM, especially that of sedges, appeared to have a high impact on NEE. Eleven PFTs, defined here, appeared to capture well the internal variation within mires, and the differences in GBM between communities were explained by the water table response of PFTs. Our results suggest the use of photosynthesizing BM, sep- arated into PFTs, in modelling ecosystem carbon exchange instead of using just total BM.
72 citations
TL;DR: With the exception of LSU D2/D3, all markers trialed displayed the potential to resolve red algal species, however, shortened COI-5P (COIms) and ITS (ITS2r) markers displayed four to five times the intrageneric divergence of shortened plastid markers and are preferred for their resolving power.
Abstract: Two DNA extraction protocols and nine variations of advocated DNA barcode markers (nuclear LSU D2/D3, ITS1, ITS2, mitochondrial COI-5P, plastid rbcL, UPA) were assessed for their abilities to yield...
69 citations
TL;DR: The possibility that some endophytic diazotrophs facilitate pine seedling growth in N-poor soils is demonstrated, as shown in the results of two experiments.
Abstract: Diazotrophic bacteria previously isolated from internal tissues of naturally regenerating lodgepole pine (Pinus contorta var. latifolia (Dougl.) Engelm.) seedlings were tested for their ability to ...
60 citations
TL;DR: Understanding how avocado responds to the presence of this pathogen could assist the de- velopment of laurel wilt-resistant avocado genotypes and inform efforts to manage this disease with other measures.
Abstract: Raffaelea lauricola causes laurel wilt of avocado, Persea americana. Host × pathogen interactions were examined with light and scanning electron microscopy. The susceptible avocado cultivar ‘Simmon...
59 citations
TL;DR: Endophytic fungi from Astragalus locoweeds were compared to Undifilum oxytropis isolates obtained from dried plant material of Oxytropis lamberteii from New Mexico and Oxy Tropis sericea from Arizona, Colorado, New Mexico, Utah, and Wyoming.
Abstract: New species of Undifilum, from locoweeds Astragalus lentiginosus Vitman and Astragalus mollissimus Torr., are described using morphological characteristics and molecular phylogenetic analyses as Un...
58 citations
TL;DR: These findings, along with data from the last 13 years in which the authors have sequenced over 100 historical and type specimens, indicate that with proper controls, amplifying DNA from red algal herbarium specimens of any age is possible.
Abstract: Saunders and McDevit recently reported their efforts to extract and amplify DNA by PCR in successively older red algal (Rhodophyta) herbarium specimens. They found that recent collections (4-11 years old) readily amplified but that archival material (decades to a century old) yielded contamination problems, diminished success correlated with age, or failed to amplify. As a solution, they proposed that epitypes be designated based on contemporary sequenced specimens. In response, we extracted and amplified in independent laboratories three loci (COI, ITS2, and rbcL) from the same 1836 Sparlingia pertusa specimen that Saunders and McDevit were unable to amplify. The use of Q-solution enhanced amplification success and likely is partly responsible for our achievements with archival specimens. These findings, along with data from the last 13 years in which we have sequenced over 100 historical and type specimens, indicate that with proper controls, amplifying DNA from red algal herbarium specimens of any age ...
TL;DR: It is suggested that monocultures of lowbush blueberries are not suit- able for optimal brood rearing, and the impact of surrounding pollen diver- sity on the health of honey bee colonies introduced in lowbushblueberries in June and cranberries in July is determined.
Abstract: Access to a rich diversity of flowering plants is very important for the development of honey bee colonies introduced in crops for pollination. The aim of this observational study was to determine ...
TL;DR: White spruce (Picea glauca (Moench Voss) cone crops were measured from 1986 to 2011 in the Kluane region of southwestern Yukon to test the hypothesis that the size of cone crops could be predicted.
Abstract: White spruce (Picea glauca (Moench) Voss) cone crops were measured from 1986 to 2011 in the Kluane region of southwestern Yukon to test the hypothesis that the size of cone crops could be predicted...
TL;DR: The molecular phylogeny recovers a similar topology to that published in recent studies and confirms three major evolutionary lines and patterns of radiation regarding the ancestors of subgenera Amerallium and Anguinum in the genus.
Abstract: This study was undertaken to better understand Allium infrageneric taxonomy, character evolution, species diversification, and patterns of radiation in disjunct species between the New and Old Worl...
TL;DR: The following hypotheses that throughfall from Populus elevates bark pH; increases relative growth rate in cephalolichens; and stimulates their growth through phosphorus (P) fertilization are tested.
Abstract: Overstory Populus has been shown to facilitate establishment by cyano- and cephalolichens on conifer branches within its dripzone; though the mechanisms behind this “dripzone effect” have yet to be...
TL;DR: The effects of a decrease in red to far-red (R/FR) ratio on shoot growth of two-week-old Arabidopsis thaliana (L.) Heynh seedlings were examined in the context of possible causal involvement of ke...
Abstract: The effects of a decrease in red to far-red (R/FR) ratio on shoot growth of two-week-old Arabidopsis thaliana (L.) Heynh. seedlings were examined in the context of possible causal involvement of ke...
TL;DR: Four frequently used methods of AMF colonization of the roots of plant species were evaluated and compared and revealed that a root length of at least 150 cm should be examined to represent a single root sample whatever the method used.
Abstract: Quantifying the proportion of roots colonized by arbuscular mycorrhizal fungi (AMF) is routine work for researchers conducting AMF studies. However, in practice, the methods are always misused, with their adaptability to different conditions neglected. In this study, four frequently used methods (root segment ±, root segment estimation, grid-line intersect, and magnified intersections) were evaluated and compared. Using the light microscopy based staining technique, we assessed AMF colonization of the roots of five plant species (Trifolium repens Linn., Zea mays Linn., Robinia pseudoacacia Linn., Populus simonii Carr., and Caragana korshinskii Kom.). The results revealed that a root length of at least 150 cm (rather than the usual 30 or 50 cm or 100 to 150 intersections generally used when following these four methods) should be examined to represent a single root sample whatever the method used. All four methods had good reproducibility, even though there was a high level of divergence among the results ...
TL;DR: Transpiration rates were manipulated by changing humidity and air movements around pot-grown plants receiving a daily supply of solutions containing 0, 1, 1.5, and 2 mmol Si·L -1 to conclude that the relative importance of active and passive processes in silica accumulation is poorly understood.
Abstract: Regulation of the uptake of silicon (Si) varies among plant species; some species may passively transport Si, through transpiration, from soils to shoots, while others actively transport silica and...
TL;DR: An architectural analysis of the structural and ontogenic properties of common buckthorn growing in the understory and under an open canopy found that ontogenic effects on growth need to be calibrated if a full description of phenotypic plasticity is to be obtained.
Abstract: While phenotypic plasticity is considered the major means that allows plant to cope with environmental heterogeneity, scant information is available on phenotypic plasticity of the whole-plant arch...
TL;DR: The results showed that four compounds had no significant effect on germination of maize seeds; however, SA or ASA soaking treatments significantly increased the root length, shoot height, and shoot and root dry weights of seedlings grown under chilling stress.
Abstract: One kind of biologically active salicylic acid (SA) analogue (acetylsalicylic acid, ASA) and two inactive compounds (4-aminosalicylic acid and 4-aminobenzoic acid), along with SA were chosen to evaluate their role in inducing chilling tolerance of two different chilling-tolerant maize (Zea mays L.) inbred lines. These compounds were applied as seed treatments or as a hydroponic application. The results showed that four compounds had no significant effect on germination of maize seeds; however, SA or ASA soaking treatments significantly increased the root length, shoot height, and shoot and root dry weights of seedlings grown under chilling stress. Hydroponic applications of SA or ASA significantly alleviated the accumulation of malondialdehyde, hydrogen peroxide, and superoxide radicals in roots and leaves of both lines under chilling stress, and the applications also increased the photosynthetic pigments, including chlorophyll a, chlorophyll b, and carotenoids. However, 4-aminosalicylic acid and 4-aminob...
TL;DR: Lichen richness and cover were significantly lower on the rock climbing sections compared with unclimbed sections and linear regression models indicated significant relationships with cover and richness to environmental response variables and climbing treatment.
Abstract: Lichen community composition was evaluated for both lichen cover and richness on a cliff face commonly used for recreational rock climbing. The sandstone outcrop is located on the Sibley Peninsula,...
TL;DR: Crop wild relatives are wild taxa with close genetic relationships to species with direct socioeconomic importance, as essential components of natural habitats and agricultural systems, their conservation and sustainable use are vital.
Abstract: Crop wild relatives (CWRs) are wild taxa with close genetic relationships to species with direct socioeconomic importance. As essential components of natural habitats and agricultural systems, thei...
TL;DR: In this article, a recombinant Arabidopsis GLYR1 was demonstrated to catalyze the NADPH-dependent reduction of both glyoxylate and SSA simultaneously to glycolate and GHB, respectively.
Abstract: Succinate semialdehyde (SSA) is a mitochondrially generated intermediate in the metabolism of γ-aminobutyrate (GABA), which accumulates in response to a variety of biotic and abiotic stresses. SSA can be reduced to γ-hydroxybutyrate (GHB) in plants exposed to various abiotic stress conditions. Recent evidence indicates that distinct cytosolic and plastidial glyoxylate reductase isoforms from Arabidopsis thaliana (L.) Heynh (GLYR1 and GLYR2, respectively) catalyze the in vitro conversion of SSA to GHB, as well as glyoxylate to glycolate, via NADPH-dependent reactions. In the present study, recombinant Arabidopsis GLYR1 was demonstrated to catalyze the NADPH-dependent reduction of both glyoxylate and SSA simultaneously to glycolate and GHB, respectively. Six-hour time-course experiments with intact vegetative wild-type Arabidopisis plants subjected to submergence demonstrated that GHB accumulates in rosette leaves, and this is accompanied by increasing levels of GABA and alanine, NADH/NAD+ and NADPH/NADP+ r...
TL;DR: Examination of ethylene as a potential signalling molecule in lace plant PCD and investigates climacteric-like behaviour during lace plant leaf development are examined.
Abstract: Programmed cell death (PCD) plays an important role in several plant developmental processes. The phytohormone ethylene has been implicated in PCD signalling in many plant systems, but it is also important in developmental processes such as seed germination, flowering, and climacteric fruit ripening. Lace plant (Aponogeton madagascariensis (Mirbel) H. Bruggen) is an aquatic monocot that develops perforated leaves via the deletion of cells through developmentally regulated PCD. The plant is ideal for studying PCD; however, little is known about the regulation of cellular death involved in this system. The current study examines ethylene as a potential signalling molecule in lace plant PCD and investigates climacteric-like behaviour during lace plant leaf development. Whole plants were treated with the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG), the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), or a combination of both. Subsequently, ethylene levels were monitored, and l...
TL;DR: A demographic history in which eastern and western distributions were disjunct during the Last Glacial Maximum and remained so through the Holocene, forming the present-day metapopulations in the Mojave Desert and Colorado Plateau is illustrated.
Abstract: Coleogyne ramosissima Torr. (blackbrush) is a dominant xerophytic shrub species in the ecotone between the warm and cold deserts of interior western North America. Amplified fragment length polymorphisms (AFLPs) were used to survey genetic diversity and population genetic structure at 14 collection sites across the species range. Analysis revealed significant population differentiation (FST = 0.103, p < 0.0001) and reasonably high levels of genetic diversity (expected heterozygosity; HE = 0.26), a surprising result for a putative paleoendemic species. Model-based Bayesian clustering, princi- pal coordinates analysis, and neighbor-joining analysis all produced support for the existence of two metapopulations, the first centered on the Mojave Desert and the second on the Colorado Plateau. These genetic data, coupled with information from Late Pleistocene and Holocene packrat (genus Neotoma Say and Ord, 1825) middens, illustrate a demographic history in which eastern and western distributions were disjunct during the Last Glacial Maximum and remained so through the Holocene, forming the present-day metapopulations in the Mojave Desert and Colorado Plateau. This strong regional genetic differentiation has implications for population persistence and migration in response to future climate change, as well as for shrubland restoration following anthropogenic disturbances such as annual grass invasion and wildfire. Resume : Coleogyne ramosissima Torr. (blackbrush) constitue une espece arbustive xerophyte de l'ecotone entre les deserts chauds et froids de l'interieur de l'ouest Nord-Americain. Les auteurs ont utilise les polymorphismes de la longueur des fragments amplifies (PFLAs) pour examiner la diversite genetique et la structure genetique des populations sur 14 sites de recolte distribues sur l'ensemble de l'aire de l'espece. Les analyses revelent une differenciation significative des populations (FST = 0,103, p < 0,0001) ainsi que des degres relativement eleves de diversite genetique (heterozygosie attendue; HE = 0,26), un resultat surprenant pour une espece presumee paleoendemique. Une modelisation basee sur le regroupement baye- sien, l'analyse des coordonnees principales et l'analyse des liaisons entre voisins (neighbor-joining analysis), toutes suppor- tent l'existence de deux metapopulations, la premiere centree sur le Desert Mojave et la seconde sur le Plateau du Colorado. Ces donnees genetiques, couplees avec l'information provenant des monticules de detritus de rats du genre Neotoma Say and Ord, 1825, illustrent une histoire demographique dans laquelle les distributions orientales et occidentales se sont disjoin- tes au cours du maximum de la derniere glaciation, pour demeurer telles quelles tout au long de l'Holocene, formant les me- tapopulations du Desert Mojave et du Plateau du Colorado. Cette forte differenciation genetique regionale a des implications pour la persistance des populations et leur migration en reaction au changement climatique future, ainsi que pour la restaura- tion des arbustaies, suite aux perturbations anthropiques comme l'invasion par des graminees annuelles et les incendies. Mots-cles : polymorphismes des longueurs des fragments amplifies, biogeographies, Plateau du Colorado, Mojave, colonisa- tion postglaciaire. (Traduit par la Redaction)
TL;DR: This study of 24 natural populations of herbaceous angiosperms shows that leafing intensity and axillary meristem size also have a general trade-off relationship at the between-plant level within a species.
Abstract: Leafing intensity—number of leaves produced per unit of supporting (nonleaf, aboveground) dry mass—determines the size of a plant’s “bud bank”, i.e., the number of axillary meristems per unit plant body or shoot size. This in turn determines the plant’s capacity for flexible and economic meristem deployment strategies as vegetative or reproductive structures. From recent research, it is now widely established that leafing intensity has a strong and isometrically negative relationship with individual leaf mass at the between-species level for both woody and herbaceous species. In the present study of 24 natural populations of herbaceous angiosperms, we show that these two traits also have a general trade-off relationship at the between-plant level within a species. Smaller resident reproductive (i.e., mature) plants generally produced smaller leaves, and plants with smaller leaves generally had higher leafing intensity, in most cases involving an isometric trade-off. For several species, however, the trade...
TL;DR: Inoculation trials identified several new hosts for C. flaccidum in Fennoscandia, namely Impatiens balsamina, Swertia fedtschenkoana, Loasa tricolor, Myrica gale, Verbena canadensis, Saxifraga spp.
Abstract: Attached and detached leaves of 60 potential host species were inoculated in the greenhouse and laboratory with aeciospores of Cronartium ribicola J.C. Fisch. from six Finnish locations and of Cron...
TL;DR: This study demonstrates a novel, systemic latitudinal gradient in lags among a large species assemblage in responses to recent climate change, particularly among the most mobile species and without anthropogenic influences.
Abstract: Contemporary climate change is driving widespread geographical range shifts among many species. If species are tracking changing climate successfully, then leading populations should experience sim...
TL;DR: Treatment of geranium foliage with the biocontrol agent Clonostachys rosea f.
Abstract: The ecological requirements for the colonization of geranium leaves by the biocontrol agent Clonostachys rosea f. catenulata strain J1446 were investigated. Although this biocontrol agent is a soil...
TL;DR: It is suggested that extended flower longevity is selected because it assures pollination suc- cess under scarce insect visits and is a selective advantage under unpredictable or scarce pollination activity.
Abstract: Flower longevity, the period of time that a flower remains open, is a crucial factor in plant reproductive fitness. Though longevity varies substantially among angiosperm species, longer flower longevities may be a selective advantage under unpredictable or scarce pollination activity. This study examined this hypothesis in Narcissus serotinus L. (Amarylli- daceae), a small Mediterranean geophyte that blooms during the autumnal rainy season. Field experiments performed in three natural populations through 3 consecutive years shows that N. serotinus has the ability to expand flower longevity when pollination has not occurred. Flowers that were open longer to pollination have higher reproductive fitness than younger flowers. As N. serotinus flowers age, there was a shift in pollination patterns since flower visits by butterflies be- came scarcer and are replaced by one small pollen beetle. Given that there was evidence of pollen limitation and that this species produces one single flower, we suggest that extended flower longevity is selected because it assures pollination suc- cess under scarce insect visits. Resume : La longevite florale, duree pendant laquelle la fleur reste ouverte, constitue un facteur crucial chez la plante pour sa performance reproductive. Bien que la longevite varie substantiellement entre les diverses especes d'angiospermes, des longevites plus etendues peuvent constituer un avantage selectif sous des conditions d'activite de pollinisation imprevisi- bles ou reduites. Les auteurs ont examine cette hypothese chez le Narcissus serotinus L. (Amaryllidaceae), une petite geo- phyte mediterraneenne fleurissant au cours de la saison pluvieuse automnale. Des experiences conduites sur le terrain dans trois populations naturelles au cours de 3 annees consecutives montrent que le N. serotinus a la capacite d'etendre sa longe- vite florale, lorsque la pollinisation n'a pas ete realisee. Les fleurs plus longuement ouvertes a la pollinisation montrent une performance reproductive plus importante que les fleurs plus jeunes. A mesure que les fleurs du N. serotinus prennent de l'âge, on observe un deplacement des patrons de pollinisation puisque les visites des fleurs par les papillons deviennent ra- res et sont remplacees par celles d'un petit insecte pollinisateur. Sachant qu'il y a une preuve de limitation pollinique et que cette espece produit une seule petite fleur, les auteurs suggerent qu'une longevite florale etendue est favorisee parce qu'elle assure le succes de la pollinisation en presence de visites rarefiees par les insectes. Mots-cles : longevite florale, pollinisation automnale, performance reproductive, pollinisation limitee, Narcissus serotinus. (Traduit par la Redaction)