scholarly journals Differentiation in Leaf Physiological Traits Related to Shade and Drought Tolerance Underlies Contrasting Adaptations of Two Cyclobalanopsis (Fagaceae) Species at the Seedling Stage

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 844 ◽  
Author(s):  
Ai-Ying Wang ◽  
Guang-You Hao ◽  
Jing-Jing Guo ◽  
Zhi-Hui Liu ◽  
Jiao-Lin Zhang ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Environmental Gradients ◽  
High Irradiance ◽  
Tree Seedlings ◽  
Physiological Mechanisms ◽  
Full Sunlight ◽  
Leaf Hydraulics ◽  
Naturally Occurring ◽  
Species Specific ◽  
Distinct Distribution

Adaptation and acclimation of tree seedlings to different combinations of light and water conditions can determine the species-specific patterns of distribution along environmental gradients and the underlying physiological mechanisms are fundamental to the understanding of such patterns. Seedlings of two Cyclobalanopsis species naturally occurring in southwest China, with distinct distribution and regeneration characteristics, were grown under 100%, 50% and 4% sunlight conditions and traits related to shade and drought tolerance were studied. Particularly, we investigated whether leaf hydraulics, photosynthetic traits and their functional coordination play an important role in determining seedling environmental adaptation and acclimation of the two species. Seedlings of C. helferiana showed characteristics adapted to high irradiance while C. rex had traits adapted to partially shaded environments. Cyclobalanopsis helferiana had significantly higher maximum net photosynthetic rate (Amax), light compensation point and light saturation point than C. rex and the contrasts were particularly large when they were grown under full sunlight. Cyclobalanopsis helferiana showed the highest Amax when grown under 100% sunlight, while C. rex exhibited the highest Amax at 50% sunlight. Similarly, under full sunlight conditions C. helferiana showed significantly higher leaf hydraulic conductance (Kleaf) than C. rex, i.e., 13.37 vs. 7.09 mmol m−2 s−1 MPa−1 (p < 0.01). The correlation between Kleaf and Amax followed a unified positive correlation across different light treatments of both species. Moreover, leaves of C. helferiana showed greater resistance to drought-induced hydraulic dysfunction and to desiccation than C. rex. The contrasts in functional traits between the two Cyclobalanopsis species are consistent with the hypothesis that there is a trade-off between shade tolerance and drought tolerance. Findings of the present study contribute to a deeper understanding of mechanisms of divergence between closely related (congeneric) species with respect to key ecophysiology associated with natural regeneration.

scholarly journals Going Wild: Lessons from Naturally Occurring T-Lymphotropic Lentiviruses

2006 ◽  
Vol 19 (4) ◽  
pp. 728-762 ◽  
Author(s):  
Sue VandeWoude ◽  
Cristian Apetrei
Keyword(s):  
Immune Responses ◽  
Natural Populations ◽  
Host Immune Responses ◽  
Experimental Systems ◽  
Naturally Occurring ◽  
Immunodeficiency Virus ◽  
New Directions ◽  
Species Specific ◽  
Lentiviral Infections ◽  
Hiv Aids

SUMMARY Over 40 nonhuman primate (NHP) species harbor species-specific simian immunodeficiency viruses (SIVs). Similarly, more than 20 species of nondomestic felids and African hyenids demonstrate seroreactivity against feline immunodeficiency virus (FIV) antigens. While it has been challenging to study the biological implications of nonfatal infections in natural populations, epidemiologic and clinical studies performed thus far have only rarely detected increased morbidity or impaired fecundity/survival of naturally infected SIV- or FIV-seropositive versus -seronegative animals. Cross-species transmissions of these agents are rare in nature but have been used to develop experimental systems to evaluate mechanisms of pathogenicity and to develop animal models of HIV/AIDS. Given that felids and primates are substantially evolutionarily removed yet demonstrate the same pattern of apparently nonpathogenic lentiviral infections, comparison of the biological behaviors of these viruses can yield important implications for host-lentiviral adaptation which are relevant to human HIV/AIDS infection. This review therefore evaluates similarities in epidemiology, lentiviral genotyping, pathogenicity, host immune responses, and cross-species transmission of FIVs and factors associated with the establishment of lentiviral infections in new species. This comparison of consistent patterns in lentivirus biology will expose new directions for scientific inquiry for understanding the basis for virulence versus avirulence.

scholarly journals Evolution of halophytes: multiple origins of salt tolerance in land plants

2010 ◽  
Vol 37 (7) ◽  
pp. 604 ◽  
Author(s):  
Timothy J. Flowers ◽  
Hanaa K. Galal ◽  
Lindell Bromham
Keyword(s):  
Salt Tolerance ◽  
Novel Species ◽  
Complex Trait ◽  
Land Plants ◽  
Salt Tolerant ◽  
Physiological Mechanisms ◽  
Multiple Origins ◽  
Naturally Occurring ◽  
Tolerant Plants

The evolution of salt tolerance is interesting for several reasons. First, since salt-tolerant plants (halophytes) employ several different mechanisms to deal with salt, the evolution of salt tolerance represents a fascinating case study in the evolution of a complex trait. Second, the diversity of mechanisms employed by halophytes, based on processes common to all plants, sheds light on the way that a plant’s physiology can become adapted to deal with extreme conditions. Third, as the amount of salt-affected land increases around the globe, understanding the origins of the diversity of halophytes should provide a basis for the use of novel species in bioremediation and conservation. In this review we pose the question, how many times has salt tolerance evolved since the emergence of the land plants some 450–470 million years ago? We summarise the physiological mechanisms underlying salt-tolerance and provide an overview of the number and diversity of salt-tolerant terrestrial angiosperms (defined as plants that survive to complete their life cycle in at least 200 mM salt). We consider the evolution of halophytes using information from fossils and phylogenies. Finally, we discuss the potential for halophytes to contribute to agriculture and land management and ask why, when there are naturally occurring halophytes, it is proving to be difficult to breed salt-tolerant crops.

scholarly journals Nanopore amplicon sequencing reveals molecular convergence and local adaptation of opsin genes

2020 ◽  
Author(s):  
Katherine M. Eaton ◽  
Moisés A. Bernal ◽  
Nathan J.C. Backenstose ◽  
Trevor J. Krabbenhoft
Keyword(s):  
Local Adaptation ◽  
Environmental Gradients ◽  
Parallel Evolution ◽  
Amplicon Sequencing ◽  
Species Flock ◽  
Closely Related Species ◽  
Oxford Nanopore ◽  
Opsin Genes ◽  
Potential Case ◽  
Species Specific

AbstractLocal adaptation can drive diversification of closely related species across environmental gradients and promote convergence of distantly related taxa that experience similar conditions. We examined a potential case of adaptation to novel visual environments in a species flock (Great Lakes salmonids, genus Coregonus) using a new amplicon genotyping protocol on the Oxford Nanopore Flongle. Five visual opsin genes were amplified for individuals of C. artedi, C. hoyi, C. kiyi, and C. zenithicus. Comparisons revealed species-specific differences in the coding sequence of rhodopsin (Tyr261Phe substitution), suggesting local adaptation by C. kiyi to the blue-shifted depths of Lake Superior. Parallel evolution and “toggling” at this amino acid residue has occurred several times across the fish tree of life, resulting in identical changes to the visual systems of distantly related taxa across replicated environmental gradients. Our results suggest that ecological differences and local adaptation to distinct visual environments are strong drivers of both evolutionary parallelism and diversification.

Salt Marsh Light Use Efficiency is Driven by Environmental Gradients and Species‐Specific Physiology and Morphology

2021 ◽  
Author(s):  
Peter A. Hawman ◽  
Deepak R. Mishra ◽  
Jessica L. O’Connell ◽  
David L. Cotten ◽  
Caroline R. Narron ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Environmental Gradients ◽  
Light Use Efficiency ◽  
Use Efficiency ◽  
Species Specific

scholarly journals Responses of Parameters for Electrical Impedance Spectroscopy and Pressure–Volume Curves to Drought Stress in Pinus bungeana Seedlings

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 359
Author(s):  
Ai-Fang Wang ◽  
Bao Di ◽  
Tapani Repo ◽  
Marja Roitto ◽  
Gang Zhang
Keyword(s):  
Drought Stress ◽  
Impedance Spectroscopy ◽  
Drought Tolerance ◽  
Osmotic Potential ◽  
Electrical Impedance ◽  
Electrical Impedance Spectroscopy ◽  
Tree Seedlings ◽  
Intracellular Resistance ◽  
Pinus Bungeana ◽  
Extracellular Resistance

Background and Objectives: Drought occurs more frequently in Northern China with the advent of climate change, which might increase the mortality of tree seedlings after afforestation due to hydraulic failure. Therefore, investigating water relations helps us understand the drought tolerance of tree seedlings. Electrical impedance spectroscopy (EIS) is widely used to assess the responses of plant tissues to stress factors and may potentially reveal the water relations of cells. The aim of this study is to reveal the relationships between EIS and water related parameters, produced by pressure–volume (PV) curves in lacebark pine (Pinus bungeana Zucc.) seedlings reacting to drought stress. Materials and Methods: Four-year-old pot seedlings were divided into three parts (0, 5, and 10 days of drought) before planting, the treated seedlings were then replanted, and finally exposed to post-planting drought treatments with the following soil relative water contents: (i) adequate irrigation (75%–80%), (ii) light drought (55%–60%), (iii) moderate drought (35%–40%), and (iv), severe drought (15%–20%). During the post-planting growth phase, the EIS parameters of needles and shoots, and the parameters of PV curves, were measured coincidently; thus, the correlations between them could be obtained. Results: The extracellular resistance (re) of needles and shoots were substantially reduced after four weeks of severe post-planting drought stress. Meanwhile, the osmotic potential at the turgor-loss point (ψtlp) and the saturation water osmotic potential (ψsat) of shoots decreased after drought stress, indicating an osmotic adjustment in acclimating to drought. The highest correlations were found between the intracellular resistance (ri) of the shoots and ψtlp and ψsat. Conclusions: EIS parameters can be used as a measure of drought tolerance. The change in intracellular resistance is related to the osmotic potential of the cell and cell wall elasticity. Extracellular resistance is a parameter that shows cell membrane damage in response to drought stress in lacebark pine seedlings.

scholarly journals A framework to bridge scales in distribution modeling of soil microbiota

2020 ◽  
Vol 96 (5) ◽  
Author(s):  
Jonas J Lembrechts ◽  
L Broeders ◽  
J De Gruyter ◽  
D Radujković ◽  
I Ramirez-Rojas ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Spatial Scales ◽  
Biotic Interactions ◽  
Environmental Niche ◽  
Distribution Models ◽  
Soil Microbiota ◽  
Soil Microbial ◽  
Critical Issues ◽  
Multiple Species ◽  
Species Specific

ABSTRACT Creating accurate habitat suitability and distribution models (HSDMs) for soil microbiota is far more challenging than for aboveground organism groups. In this perspective paper, we propose a conceptual framework that addresses several of the critical issues holding back further applications. Most importantly, we tackle the mismatch between the broadscale, long-term averages of environmental variables traditionally used, and the environment as experienced by soil microbiota themselves. We suggest using nested sampling designs across environmental gradients and objectively integrating spatially hierarchic heterogeneity as covariates in HSDMs. Second, to incorporate the crucial role of taxa co-occurrence as driver of soil microbial distributions, we promote the use of joint species distribution models, a class of models that jointly analyze multiple species’ distributions, quantifying both species-specific environmental responses (i.e. the environmental niche) and covariance among species (i.e. biotic interactions). Our approach allows incorporating the environmental niche and its associated distribution across multiple spatial scales. The proposed framework facilitates the inclusion of the true relationships between soil organisms and their abiotic and biotic environments in distribution models, which is crucial to improve predictions of soil microbial redistributions as a result of global change.

scholarly journals The effect of flooding on the exchange of the volatile C<sub>2</sub>-compounds ethanol, acetaldehyde and acetic acid between leaves of Amazonian floodplain tree species and the atmosphere

2008 ◽  
Vol 5 (4) ◽  
pp. 1085-1100 ◽  
Author(s):  
S. Rottenberger ◽  
B. Kleiss ◽  
U. Kuhn ◽  
A. Wolf ◽  
M. T. F. Piedade ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Ethanol Production ◽  
Tree Species ◽  
Proton Transfer Reaction ◽  
Early Morning ◽  
Enzymatic Oxidation ◽  
Tree Seedlings ◽  
Emission Rates ◽  
Transpiration Stream ◽  
Species Specific

Abstract. The effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid in relation to assimilation and transpiration was investigated with 2–3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited measurable emissions of any of the compounds, but rather low deposition of acetaldehyde and acetic acid was observed instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid were only observed from the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning suggest that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted, though we can not totally exclude other production pathways. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (25–1700 nmol m−2 min−1 for ethanol and 5–500 nmol m−2 min−1 for acetaldehyde). Acetic acid emissions reached 12 nmol m−2 min−1. The observed differences in emission rates between the tree species are discussed with respect to their root adaptive strategies to tolerate long term flooding, providing an indirect line of evidence that the root ethanol production is a major factor determining the foliar emissions. Species which develop morphological root structures allowing for enhanced root aeration produced less ethanol and showed much lower emissions compared to species which lack gas transporting systems, and respond to flooding with substantially enhanced fermentation rates and a non-trivial loss of carbon to the atmosphere. The pronounced differences in the relative emissions of ethanol to acetaldehyde and acetic acid between the tree species indicate that not only the ethanol production in the roots but also the metabolic conversion in the leaf is an important factor determining the release of these compounds to the atmosphere.

scholarly journals The Effects of Forestry Site Preparation on Mountain Beaver Demographics and Associated Damage to Tree Seedlings

2010 ◽  
Vol 25 (3) ◽  
pp. 127-135
Author(s):  
Wendy Arjo
Keyword(s):  
Pacific Northwest ◽  
Management Practices ◽  
Site Preparation ◽  
Home Ranges ◽  
Tree Seedlings ◽  
Animal Damage ◽  
The Pacific ◽  
Mountain Beaver ◽  
Aplodontia Rufa ◽  
Species Specific

Abstract Timber resources are a vital part of the economy in the Pacific Northwest, yet reforestation efforts are often hampered by animal damage. Understanding the factors that influence seedling damage can assist managers in implementing appropriate techniques to reduce species-specific damage. I radio-collared and monitored mountain beavers (Aplodontia rufa) from preharvest to seedling planting to determine the impacts of forest management practices on demographics. In addition, I monitored Douglas-fir (Pseudotsuga menziesii) seedlings on 28 plots on two harvest units (Vesta and Schoolhouse) to determine the effects of chemical site preparation on mountain beaver foraging and subsequent seedling damage. Mountain beaver densities differed between silvicultural treatments (F3,39 = 3.58, P < 0.02), although reproductive success did not (χ2 = 0.14, df = 1, P = 0.70). Larger mountain beaver home ranges were documented in the mature timber compared with those following harvest. Home ranges were also larger in the chemical site preparation portion of the unit (mean = 3.37 ± 0.9 ha) than in the nontreated portion of the unit (mean = 0.82 ± 0.17 ha) on Vesta. Herbicide treatment did not promote seedling damage on either unit. Vegetation does not appear to be the only factor influencing mountain beaver movements and seedling damage. Availability of water is very important for mountain beavers and may also influence their foraging choice, as well as contributing to their increased movements in mature timber (reduced groundwater) versus clearcut areas. Understanding the effects of vegetation on population demographics and subsequent seedling damage may allow for initiating a nonlethal management method using alternative forage.

scholarly journals Growth, photosynthesis and stress indicators in young rosewood plants (Aniba rosaeodora Ducke) under different light intensities

2005 ◽  
Vol 17 (3) ◽  
pp. 325-334 ◽  
Author(s):  
José Francisco de Carvalho Gonçalves ◽  
Denize Caranhas de Sousa Barreto ◽  
Ulysses Moreira dos Santos Junior ◽  
Andreia Varmes Fernandes ◽  
Paulo de Tarso Barbosa Sampaio ◽  
...  
Keyword(s):  
Photochemical Efficiency ◽  
Biomass Accumulation ◽  
Photosynthetic Performance ◽  
High Irradiance ◽  
Relative Growth Rates ◽  
Full Sunlight ◽  
Light Intensities ◽  
The Family ◽  
Protection Mechanisms ◽  
Intense Exploitation

Aniba rosaeodora is an Amazonian tree species that belongs to the family Lauraceae. Due to intense exploitation for extraction of essential oils (mainly linalol), A. rosaeodora is now considered an endangered species. On the other hand, there is little information about its ecophysiology which would be useful to support future forest planting programs. Hence, the effect of different light intensities on the growth and photosynthetic characteristics of young plants of A. rosaeodora was studied. Nine-month-old plants were subjected to four light treatments (T1= 10 a 250 µmol.m-2.s-1 / control; T2=500 to 800, T3=700 to 1000 and T4=1300 to 1800 µmol.m-2.s-1 / full sunlight). Allometric variables, gas exchange, contents of pigments and chlorophyll a fluorescence were analysed. As to the relative growth rates, it was found that plants of A. rosaeodora showed higher biomass accumulation when grown under intermediary irradiance conditions (T2). The best photosynthetic performance was achieved under conditions of T3. When growth was correlated with photosynthesis, it was found that plants under treatments T2 and T3 presented better responses in comparison with the lowest (T1) and highest (T4) light extremes. The highest pigment contents were obtained for plants in the shade (T1) and the lowest for those exposed to full sunlight (T4). The photochemical efficiency of photosystem II (Fv/Fm) was found that only plants in the shade treatment (T1) presented no stress from high irradiance. These findings suggest that both treatments (T1 and T4) altered the function of the A. rosaeodora plants, inhibiting photosynthesis and growth. Plants of A. rosaeodora developed photo-protection mechanisms under full sunlight. However, the species presented better photosynthetic response and biomass gain under intermediary irradiance conditions, displaying relative physiological plasticity, during the seedling phase.

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