New paper published – Both spatiotemporal connectivity and habitat quality limit the immigration of forest plants into wooded corridors

Text by Taavi Paal and Jaan Liira

What limits forest plant migration along wooded corridors?

Europe’s natural forest is heavily fragmented by agricultural land. Such isolation threatens the long-term persistence of forest biodiversity. The concept of patch-corridor-matrix system suggests that isolated patches can be ecologically connected by a corridor network. As forest-specialist plants (termed also as “ancient forest plants”) are adapted to a stable forest environment and are considered to be poor long-distance dispersers, their use of wooded corridors hasn’t got much attention. We asked why? As in the long run even slowly dispersing species should eventually immigrate into corridors. Maybe the edge effect limits the establishment? Or is the positive expectation on the functionality of corridors driven by the response of habitat generalist species?

To avoid the early-successional underestimation of arrival success, we concentrated our study on older (>50 years) wooded corridors. The isolation effect was evaluated by sampling two types of corridors: directly connected to source forest and isolated mid-field corridors, and margins of ancient forests were used as a comparison habitat (as they are also prone to edge effects).

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Forest connecting alley near Vara, Estonia (pic by Taavi Paal)

Overall, forest generalists prevailed over a small number of forest specialists in wooded corridors. The connectivity/isolation effect ruled over the edge effect as the number of forest specialists in connected corridors was analogous to forest edges. The expectation of ineffective immigration was met only in isolated corridors which harboured a few forest specialists, but still many generalists. Tested in other terms, forest specialists depended on historical stability of the surrounding forest landscape, while forest generalists reflected the status of present-day landscape configuration. The poorly detected edge effect was probably suppressed by overall canopy closure of overstorey and the width of the corridor. In semi-open corridors forest specialists were outcompeted by open habitat plants.

What can be done in order to improve the environment of corridors for forest specialists? As forest specialists cannot cope with rapid changes in forest landscape configuration, wide corridors with suitable shaded conditions and directly connected to ancient forests should be maintained for many decades. Ecologically functioning of wooded corridors can be ensured with the width of at least two lines of mature trees and with overhanging side branches. Ground disturbances should also be kept to a minimum (e.g. ditch construction, frequent mowing) as they promote generalist species. However, as the formation of shade providing overstorey takes decades, historical alleys should be sustainably managed and their connectivity with forests should be improved.

 

Citation: Paal, T., Kütt, L., Lõhmus, K. & Liira, J. 2017. Both spatiotemporal connectivity and habitat quality limit the immigration of forest plants into wooded corridors. Plant Ecology (in press). doi: 10.1007/s11258-017-0700-7 (link to full text)

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Anemone nemorosa growing in an alley (pic by Taavi Paal)

Abstract:

Extensive afforestation of agricultural areas has increased the importance of green corridors as a dispersal network. We tested the effect of spatiotemporal connectivity, edge effect and habitat structural quality of wooded corridors on the long-term immigration success of forest specialist plants relative to the performance of forest generalists. In agricultural landscapes of central and southern Estonia, we sampled 28 historically connected and 52 isolated tree lines and alleys with a minimum age of 50 years, and 93 edges of ancient forests. The regional pool of common forest plants was compiled using species’ frequency data in 91 ancient forests. Both landscape connectivity and habitat quality affected the richness of response groups, but specialists and generalists responded to different drivers. Forest specialists required long-term neighbourhoods of ancient forest and benefited from a direct connection between forest and corridor. Habitat generalists reacted positively to the recently modified structure of the landscape. When a corridor was connected to forest, the dual edge in the corridor did not result in an increased negative edge effect on forest specialist arrival. Even if both specialists and generalists required wide corridors with optimum shade, forest specialists also benefited from mature overstorey and outward overhanging branches, whereas forest generalists used disturbance-created microhabitats. We conclude that only wooded corridors with long-term connectivity to seed source forests and widely branched tree canopies will function as a green infrastructure supporting forest-specific biodiversity.

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New paper published – Emissions of carotenoid cleavage products upon heat shock and mechanical wounding from a foliose lichen

Text by Lauri Laanisto

I like that this paper starts with a metaphor: “Chlorophyll (Chl) is a double-edged sword for plants.” Because “This molecule is capable of harvesting sunlight, initiating the process of photosynthesis, but it also involves an unavoidable risk of photooxidation.” Though I´m not sure whether this metaphor indeed holds water. The edges of this metaphoric sword seem to be awfully uneven. Especially because plants have developed pigments against it. And this paper tries to figure out which edge would cut the holder.

Another kind of curious aspect of this study is that while the whole Introduction part deals with vasular plants and how VCCPs (which are not defined in the paper so that I would actually understand what the acronym stands for) are stress regulated, the whole experiment was done with a lichen! The argument for that is: “We have chosen such a model and not a vascular plant to simplify the pathway between the thylakoids and the open atmosphere.” Is it really a substantial reason to make such a fundamental change in the study object? It´s a curious question…

Anyway, based on the results, the authors conclude that the presence of VCCPs could indicate the degradation process in caroteinoids. Whether the lichen was under heat stress or not. And in comparison with other volatiles, the emission rate of VCCPs had the lowest change. It went up just a little.

I kind of got the feeling that this paper represents the results of an experiment not going as expected. For example, the concluding paragraph reads as follows: “Overall, the present work shows that VCCPs are produced constitutively and released from the thalli of L. pulmonaria. However, although VCCP emissions from photosynthetic tissues might, potentially, serve similar functions as other well-recognized volatile infochemicals (LOX products, methyl salicylate, methyl jasmonate) that act as cues in biocommunication and plant signaling, low emission rates of VCCPs, and the absence of quantitative relationship with stress intensity, suggests that it is unlikely that these volatiles play such a role in the studied lichen species.”

Citation: García-Plazaola, J. I., Portillo-Estrada, M., Fernández-Marín, B., Kännaste, A., & Niinemets, Ü. (2017). Emissions of carotenoid cleavage products upon heat shock and mechanical wounding from a foliose lichen. Environmental and Experimental Botany, 133, 87-97. (link to full text)

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Lobaria pulmonaria (from Wikipedia)

Abstract:

Carotenoids constitute a major target of chloroplastic photooxidative reactions, leading to the formation of several oxidized derivatives and cleavage products, some of which are volatile (VCCPs). Among them, β-cyclocitral (β-CC), at least, is a retrograde signaling molecule that modulates the activity of many key physiological processes. In the present work, we aimed to study whether β-CC and other VCCPs are released into the atmosphere from photosynthetic tissues. To overcome stomatal limitations, the foliose chlorolichen Lobaria pulmonaria was used as the model system, and the emissions of biogenic volatiles, induced by heat and wounding stresses, were monitored by proton-transfer reaction time-of-flight mass-spectrometry (PTR-TOF-MS) and gas-chromatography (GC–MS). Prior to stress treatments, VCCPs were emitted constitutively, accounting for 1.3% of the total volatile release, with β-CC being the most abundant VCCP. Heat and wounding stresses induced a burst of volatile release, including VCCPs, and a loss of carotenoids. Under heat stress, the production of β-CC correlated positively with temperature. However the enhancement of production of VCCPs was the lowest among all the groups of volatiles analyzed. Given that the rates of carotenoid loss were three orders of magnitude higher than the release rates of VCCPs and that these compounds only represent a minor fraction in the blend of volatiles, it seems unlikely that VCCPs might represent a global stress signal capable of diffusing through the atmosphere to different neighboring individuals.

 

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New paper published – Selection of source material for introduction of the locally rare and threatened fern species Asplenium septentrionale

Text by Jaan Liira
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Asplenium septentrionale in nature (photo by Kai Rünk)

Forked spleenwort, Asplenium septentrionale, is a mainly petrophilous fern species in European mountains and rare on acidic siliceous rocks in lowland areas of the continent, where habitats are fragmented and populations isolated. In Estonia, the single extant population occupies a restricted area and is threatened by human disturbances. An introduction project of the species was prepared to estimate the potential to form new populations in new protected sites using ex-situ propagated young sporophytes as transplantation material, by comparing the recruitment biology of three different donor populations. First, we carried out a laboratory breeding experiment to evaluate the populations’ ability for intra-gametophytic selfing, and secondly, in a common garden estimated the fitness of offspring. The results showed that the only Estonian donor population showed very high capacity for intra-gametophytic selfing, as well as high rate of sporophytic mortality (83%), and these rates were comparable to one of two reference donor populations in Finland. However, plants of Estonian population were smaller, representing a unique locally adapted genotype. Therefore, it needs more efficient protection in its present location. We suggest that planting material for introduction into nearby new locations should be collected from the local population, as the best locally adapted. Only in the risk of severe environmental change and of extinction, several neighbouring populations could be pooled to maximise genetic diversity.

Citation: Rünk, K., Pihkva, K., Liira, J., & Zobel, K. (2016). Selection of source material for introduction of the locally rare and threatened fern species Asplenium septentrionale. Plant Ecology & Diversity, 9: 167-173 (link to full text)

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Asplenium in pot experiment (photo by Kai Rünk)

Abstract:

Background: Forked spleenwort, Asplenium septentrionale, is a mainly petrophilous fern species in European mountains and rare on acidic siliceous rocks in lowland areas of the continent, where habitats are fragmented and populations isolated. In Estonia, the single extant population is very small, occupies a restricted area and is threatened by human disturbances. An introduction project of the species was prepared to form new populations in new protected sites using ex-situ propagated young sporophytes as transplantation material.

Aims: To obtain data on the species recruitment population biology and provide context information for selecting donor plant material.

Methods: We sampled three regional/local donor populations. First, we carried out a laboratory breeding experiment to evaluate the populations’ ability for intra-gametophytic selfing. Second, to estimate differences in fitness of offspring among the populations, we grew young sporophyte plants in a pot experiment under controlled conditions in a common garden.

Results: The Estonian population showed very high capacity (90%) for intra-gametophytic selfing, as well as high rate of sporophytic mortality (83%), but the rates are comparable to one of the reference populations in Finland. However, plants of Estonian population were smaller.

Conclusions: The Estonian population may represent a unique pre-adapted or locally adapted genotype; therefore, it needs more efficient protection in its present location. Planting material for introduction should be collected from the local population, as the best locally adapted. Only in the risk of severe environmental change and of extinction, several neighbouring populations could be pooled to maximise genetic diversity.

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New paper published – Global leaf trait estimates biased due to plasticity in the shade

Text by Trevor Keenan

Our new paper, “Global leaf trait estimates biased due to plasticity in the shade” (link to full text) was published online in Nature Plants on December 19th. It highlights a literally shady issue in plant science that has in some cases led to the underestimation of plant rates of growth and photosynthesis, among other traits.

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The paper uses recent understanding of how leaf traits vary in response to light, along with a variety of global databases, to estimate trait values in fully sunlit conditions. It finds that a large proportion of trait values in current databases are significantly lower than our estimates, indicating that they were actually measured in the shade. As a result, global plant databases and models may require updating to better account for plant responses to full-sun conditions.

This issue may stem from a common tendency in fieldwork to report leaf measurements taken in partially shaded conditions as existing in more fully sunlit conditions. Often when researchers are in the field, it’s hard to get to leaves at the top of trees, particularly in densely vegetated areas such as tropical forests where the canopies can reach over 100 feet in height. In other cases, understory plants grow mostly in the shade, so it is impossible to sample in full sun. Traits vary quite a lot in the canopy, so if you don’t sample from the top all of your samples will be biased.

 

Large light-dependent variations in leaf traits

In plant fieldwork, full-sun conditions are defined as those in which a plant receives the maximum amount of sunlight, typically at the top of a canopy, but most leaves do not grow in full-sun conditions.

Leaves at the bottom of the canopy in a tropical rainforest may receive 100 times less sunlight than those at the top of the canopy. And many leaf characteristics—which are integral to vital leaf functions such as carbon uptake and photosynthesis—can vary 20-fold between the top and bottom leaves on the same plant. For example, the highest concentration in nitrogen is at the top, where you have the most sunlight. Plants allocate a lot of nutrients there so they can ‘profit’ from it the most.

 

Cutting to the root of a data problem

Together with Ülo Niinemets, we evaluated leaf data from several databases—covering hundreds of plant species and spanning most regions of the world. We used data from those studies that reported extra information about the specific location of the sampled leaves in the canopy as a benchmark for other studies’ data.

The misreported sun vs. shade conditions are likely most pronounced in tropical regions. Because these regions of tropical vegetation are also considered to be the planet’s largest “carbon sinks” in removing carbon dioxide from the atmosphere, these are some of the most important areas to focus on.

Better accounting of light conditions that sampled leaves are growing in could help to improve models that account for plants’ total rate of photosynthesis and better quantify their role as a carbon sink, for example, and for plants’ adaptability to changing conditions. It can also identify important correlations between which plant traits are most pronounced under different lighting conditions.

More accurate sampling methods can ultimately help improve scientists’ understanding of whole ecosystem structure and function, and to understand how plants respond to factors such as climate change.In addition to improved reporting of sunlit conditions, there is also a need for better accounting of plant ages in field studies, as age may affect leaf chemistry and function, according to the study.

We conclude that field studies must take more care in accurately reporting sunlit vs. shaded conditions and age-driven trait responses in leaves.

New techniques are emerging to improve data collection in the field. The study notes that some field research has used a shotgun approach to sample leaves at the top of the canopy—firing a shotgun to clip off leaves that are otherwise out of reach—though this technique alters the water flow that exists in attached leaves, so it can affect photosynthesis measurements.

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LIDAR, a laser-based mapping technology, has found more use in plant field work, by providing 3-D images of forest structure, for example, and physics-based computer simulations are improving in their ability to model how leaves transfer energy from sunlight. There is definitely a path forward in technological and scientific advances, along with new measurement approaches.

 

This blog post was adapted from the Lawrence Berkeley National Lab. News Center: http://newscenter.lbl.gov/2016/12/19/new-leaf-study-sheds-light-on-shady-past/

 

Citation: Keenan, T. F. and Niinemets, Ü. (2016). Global leaf trait estimates biased due to plasticity in the shade. Nature plants, 3, 16201, DOI: 10.1038/nplants.2016.201 (link to full text)

 

Abstract:

The study of leaf functional trait relationships, the so-called leaf economics spectrum, is based on the assumption of high-light conditions (as experienced by sunlit leaves). Owing to the exponential decrease of light availability through canopies, however, the vast majority of the world’s vegetation exists in at least partial shade. Plant functional traits vary in direct dependence of light availability, with different traits varying to different degrees, sometimes in conflict with expectations from the economic spectrum. This means that the derived trait relationships of the global leaf economic spectrum are probably dependent on the extent to which observed data in existing large-scale plant databases represent high-light conditions. Here, using an extensive worldwide database of within-canopy gradients of key physiological, structural and chemical traits, along with three different global trait databases, we show that: (1) accounting for light-driven trait plasticity can reveal novel trait relationships, particularly for highly plastic traits (for example, the relationship between net assimilation rate per area (Aa) and leaf mass per area (LMA)); and (2) a large proportion of leaf traits in current global plant databases reported as measured in full sun were probably measured in the shade. The results show that even though the majority of leaves exist in the shade, along with a large proportion of observations, our current understanding is too focused on conditions in the sun.

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New paper published – Toxic Influence of Key Organic Soil Pollutants on the Total Flavonoid Content in Wheat Leaves

Text by Lauri Laanisto

Another study through Ülo Niinemets´connection in Romania (see the one about the effects of wifi and phone waves on volatiles here). This time they looked into how textile dyes and antibiotics (which are the main classes of organic pollutants in soils and fresh waters) affect wheat growth and development. It was an experiment done in the lab, where they already added pollutants to the soils 14 days after sowing the seeds. They took biochemically very detailed approach towards the pollutants. And as expected, dyes and antibiotics had significantly affected wheat leaf flavonoids, which in turn indicate the amount of stress plant is enduring. Significant differences were detected with all six pollutants studied.

I guess the results of this study are not very surprising. Unfortunately…

Citation: Copaciu, F., Opriş, O., Niinemets, Ü., & Copolovici, L. (2016). Toxic Influence of Key Organic Soil Pollutants on the Total Flavonoid Content in Wheat Leaves. Water, Air, & Soil Pollution, 227: 196, DOI 10.1007/s11270-016-2888-x. (link to full text)

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Inducing stress on what (pic… actually painting by Van Gogh, 1889)

Abstract:

Textile dyes and antibiotics are two main classes of environmental pollutants which could be found in soil and water. Those persistent pollutants can have a negative influence on plant growth and development and affect the level of secondary metabolites. In the present work, we studied the effect of textile dyes and antibiotics on total leaf flavonoid contents in wheat (Triticum aestivum L.). Contaminant solutions were applied daily using concentrations of 0.5 mg L−1 (lower) and 1.5 mg L−1 (higher dose) for either 1 or 2 weeks. We observed that exposure to the higher concentration of textile dyes resulted in a reduction in flavonoid content while antibiotics enhanced flavonoid contents at lower doses of exposure and reduced at higher doses of exposure. These results suggest that diffuse chronic pollution by artificial organic contaminants can importantly alter antioxidative capacity of plants.

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New paper published – Induction of stress volatiles and changes in essential oil content and composition upon microwave exposure in the aromatic plant Ocimum basilicum

Text by Lauri Laanisto

Ok, this study is basically about how phone and internet waves (i.e. electromagnetic pollution) affect the volatiles and essential oils in basil (and there are lots of them in basil). So, apparently these waves either lower the amount of some compounds and raise the others. It´s a stress! But, like the authors conclude that although: “However, the composition of the studied plant was significantly altered, and it remains to be investigated whether such changes alter culinary or health properties of the essential oil.”

Thus, so far we do not yet know whether it is ok to answer the phone or check mail while tending the herb garden or not… It´s a pretty avant garde(n) conundrum.

The study was conducted in Romania and authored by a former post-doc in Ülo Niinemets´s lab, Lucian Copolovici. And that is how Ülo and EcolChange got involved.

Citation: Lung, I., Soran, M. L., Opriş, O., Truşcă, M. R. C., Niinemets, Ü., & Copolovici, L. (2016). Induction of stress volatiles and changes in essential oil content and composition upon microwave exposure in the aromatic plant Ocimum basilicum. Science of The Total Environment, 569, 489-495. (link to full text)

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A sign for your garden. Just in case! (pic from here)

Abstract:
Exposure to sustained low intensity microwaves can constitute a stress for the plants, but its effects on plant secondary chemistry are poorly known. We studied the influence of GSM and WLAN-frequency microwaves on emissions of volatile organic compounds and content of essential oil in the aromatic plant Ocimum basilicum L. hypothesizing that microwave exposure leads to enhanced emissions of stress volatiles and overall greater investment in secondary compounds. Compared to the control plants, microwave irradiation led to decreased emissions of β-pinene, α-phellandrene, bornyl acetate, β-myrcene, α-caryophyllene and benzaldehyde, but increased emissions of eucalyptol, estragole, caryophyllene oxide, and α-bergamotene. The highest increase in emission, 21 times greater compared to control, was observed for caryophyllene oxide. The irradiation resulted in increases in the essential oil content, except for the content of phytol which decreased by 41% in the case of GSM-frequency, and 82% in the case of WLAN-frequency microwave irradiation. The strongest increase in response to WLAN irradiation, > 17 times greater, was observed for hexadecane and octane contents. Comparisons of volatile compositions by multivariate analyses demonstrated a clear separation of different irradiance treatments, and according to the changes in the volatile emissions, the WLAN-frequency irradiation represented a more severe stress than the GSM-frequency irradiation. Overall, these results demonstrating important modifications in the emission rates, essential oil content and composition indicate that microwave irradiation influences the quality of herbage of this economically important spice plant.
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New paper published – Regulation of Floral Terpenoid Emission and Biosynthesis in Sweet Basil (Ocimum basilicum)

Text by Lauri Laanisto

It´s a pretty chemical paper about the volatiles emitted by different organs of basil. This study was led by Chinese postdoc Yifan Jiang, who together with Jiayan, Shuai and Ülo (all from Ülo Niinemets´ workgroup) studied the volatile emissions of Sweet basil (Ocimum basilicum). The idea was to find out which organs emit which molecules and how much. Intraspecific volatile variability of 41 compounds (check table 2)!

Citation: Jiang, Y., Ye, J., Li, S., & Niinemets, Ü. (2016) Regulation of Floral Terpenoid Emission and Biosynthesis in Sweet Basil (Ocimum basilicum). Journal of Plant Growth Regulation, 35: 921–935, DOI 10.1007/s00344-016-9591-4 (link to full text)

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Basil! (pic from here)

Abstract:

Past studies have focused on the composition of essential oil of Ocimum basilicum leaves, but data on composition and regulation of its aerial emissions, especially floral volatile emissions, are scarce. We studied the chemical profile, within-flower spatial distribution (sepals, petals, pistils with stamina, and pedicels), diurnal emission kinetics and effects of exogenous methyl jasmonate (MeJA) application on the emission of floral volatiles by dynamic headspace collection, and identification using gas chromatography-mass spectrometry (GC–MS) and proton-transfer reaction mass spectrometry. We observed more abundant floral emissions from flowers compared with leaves. Sepals were the main emitters of floral volatiles among the flower parts studied. The emissions of lipoxygenase compounds and monoterpenoids, but not sesquiterpene emissions, displayed a diurnal variation driven by light. Response to exogenous MeJA treatment of flowers consisted of a rapid stress response and a longer-term acclimation response. The initial response was associated with enhanced emissions of fatty acid derivatives, monoterpenoids, and sesquiterpenoids without variation of the composition of individual compounds. The longer-term response was associated with enhanced monoterpenoid and sesquiterpenoid emissions with profound changes in the emission spectrum. According to correlated patterns of terpenoid emission changes upon stress, highlighted by a hierarchical cluster analysis, candidate terpenoid synthases responsible for observed diversity and complexity of released terpenoid blends were postulated. We conclude that flower volatile emissions differ quantitatively and qualitatively from leaf emissions, and overall contribute importantly to O. basilicum flavor, especially under stress conditions.

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New paper published – Multi-Substrate Terpene Synthases: Their Occurrence and Physiological Significance

Text by Leila Pazouki

Some months after we published the original research article entitled “Germacrene A Synthase in Yarrow (Achillea millefolium) Is an Enzyme with Mixed Substrate Specificity: Gene Cloning, Functional Characterization and Expression Analysis” in Frontiers in Plant Science journal (see the blog post here), they invited us to write Focused Review article based on the recommendation of Prof Kazuki Saito, the chief editor of the specialty section. The original research article was democratically chosen based on the Frontiers online analytics systems to “climb the tier”.

The idea was to put this work into a broader context, explain what the main questions are and where this work might lead.

As the main focus of the article (Germacrene A Synthase in Yarrow…) was the isolation of multi-substrate terpene synthase, we focused in this review paper on the occurrence, physiological significance and proposed process for the evolution of multi-substrate terpene synthases in plants.

Our study suggests that multi-substrate use is more common in plants than generally thought and advocates for conduction of further systematic studies using multiple substrates across phylogenetically different plant groups harboring terpene synthases (TPSs) from different clades to gain an insight into the existence of the capacity for multi-substrate use across plant kingdom. The overall significance of alternative activities of multi-substrate enzymes will critically depend on the enzyme specificity and relative availability for different substrates. Perturbation of terpenoid metabolism under stress conditions can lead to enhanced substrate exchange between cytosol and plastids as well as modifications in the expression of enzymes responsible for product pool sizes and thus, favor synthesis of terpenoids according to non-conventional pathways.

Citation: Pazouki, L., & Niinemets, Ü. (2016). Multi-Substrate Terpene Synthases: Their Occurrence and Physiological Significance. Frontiers in Plant Science, 7, DOI: 10.3389/fpls.2016.01019 (link to full text)

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Many shades of yarrow (pic from here)

Abstract:

Terpene synthases are responsible for synthesis of a large number of terpenes in plants using substrates provided by two distinct metabolic pathways, the mevalonate-dependent pathway that is located in cytosol and has been suggested to be responsible for synthesis of sesquiterpenes (C15), and 2-C-methyl-D-erythritol-4-phosphate pathway located in plastids and suggested to be responsible for the synthesis of hemi- (C5), mono- (C10), and diterpenes (C20). Recent advances in characterization of genes and enzymes responsible for substrate and end product biosynthesis as well as efforts in metabolic engineering have demonstrated existence of a number of multi-substrate terpene synthases. This review summarizes the progress in the characterization of such multi-substrate terpene synthases and suggests that the presence of multi-substrate use might have been significantly underestimated. Multi-substrate use could lead to important changes in terpene product profiles upon substrate profile changes under perturbation of metabolism in stressed plants as well as under certain developmental stages. We therefore argue that multi-substrate use can be significant under physiological conditions and can result in complicate modifications in terpene profiles.

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EcolChange seminar on 17th of January – Jörg-Peter Schnitzler

Seminar of the Centre of Excellence EcolChange

Prof. Dr. Jörg-Peter Schnitzler: „Population dynamics in a plant (tansy)-aphid-ant system influenced by chemotypic variations in terpenes emitted from storage pools“

Tuesday, 17 January 2017 at 11:15, Tartu, Kreutzwaldi 5 (Metsamaja), room D143

Prof. Dr. Jörg-Peter Schnitzler from German Research Center for Environmental Health is visiting Estonia as the oponent of Leila Pazouki PhD Thesis.

More information: Tiia Kurvits tiia.kurvits@emu.ee

Aphids Ants Leaf Kennel Macro

Aphids and ants inducing volatiles (pic from here)

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New paper published – Shedding light on shade: ecological perspectives of understorey plant life

Text by Lauri Laanisto

This paper has been out already since August. But as this is a review paper, hopefully the point of this paper has not yet became obsolete. Shade seems to be a pretty sustainable property of almost all communities dominated by woody plants. And if shade is present, then all the shade-accompanying factors are probably present as well, in some form or another. And these accompanying factors are mostly what our review is about. Shade is not just lack of light, but also changed humidity, soil conditions, different herbivores and no on. Moreover, shade affects species´ capability to polytolerate other abiotic stresses as well.

A while ago Ülo received an invitation to contribute with a review paper to a new review series in Plant Ecology & Diversity called Grubb review. Obviously after Peter J. Grubb. (Read more about these reviews.) Fernando, Ülo and Miguel had written a review paper couple of years ago, which had stayed unpublished. So we decided to use it as foundation for our Grubb review. I updated the literature, wrote couple of additional sections and deleted some sections that we thought were not relevant any longer. And that was it…

Full citation: Valladares, F., Laanisto, L., Niinemets, Ü., & Zavala, M. A. (2016). Shedding light on shade: ecological perspectives of understorey plant life. Plant Ecology & Diversity, 9(3), 237-251. (link to full text)

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Shady forest in Puhtu, Estonia (pic from here)

Abstract:

Shade, in ecological sense, is not merely a lack of light, but a multi-faceted phenomenon that creates new and complex settings for community and ecosystem dynamics. Tolerating shade therefore affects plants’ ability to cope with other stressors, and also shape its interactions with surrounding organisms. The aim of this broad review was to map our current knowledge about how shade affects plants, plant communities and ecosystems – to gather together knowledge of what we know, but also to point out what we do not yet know. This review covers the following topics: the nature of shade, and ecological and physiological complexities related to growing under a canopy; plants’ capability of tolerating other stress factors while living under a shade – resource trade-offs and polytolerance of abiotic stress; ontogenetic effects of shade tolerance; coexistence patterns under the canopy – how shade determines the forest structure and diversity; shade-induced abiotic dynamics in understorey vegetation, including changing patterns of irradiance, temperature and humidity under the canopy; shade-driven plant–plant and plant–animal interactions – how shade mediates facilitation and stress, and how it creates differentiated environment for different herbivores and pollinators, including the role of volatile organic compounds. We also discuss the ways how vegetation in understorey environments will be affected by climate change, as shade might play a significant role in mitigating negative effects of climate change. Our review shows that living under a shade affects biotic and abiotic stress tolerance of plants, it also influences the outcomes of both symbiotic and competitive plant–plant and plant–animal interactions in a complex and dynamic manner. The current knowledge of shade-related mechanisms is rather ample, however there is much room for progress in integrating different implications of the multifaceted nature of shade into consistent and integral understanding how communities and ecosystems function.

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