New paper published – Changes of secondary metabolites in Pinus sylvestris L. needles under increasing soil water deficit

Text by Lauri Laanisto

Together with Spanish colleagues, Ülo has published a study about how Scots pine´s primary and secondary metabolism in the needles changes when the tree is experiencing water deficit in soil. Frome the methodoligical point of view it is a rather run-of-the-mill small-scale study concentrating on a single stress factor in one species. Pretty self-explanatory stuff. Though, note the fact that the authors are also describing different phases of the response process, which is something that is not so common.

Such studies could be (or rather will be) vital for eventually drawing more comprehensive conclusions about how plants react to different stress factors. If you could put together 100+ of such studies, it could result in a pretty seminal meta-analysis (I am after all a macroecologist…). However, conducting such meta-analysis is currently not possible. Because such studies are actually not very abundant. We do not yet know the fundamentals in this fundamental area of research! Which for me is a quite convincing argument for publishing this kind of research.

Citation: Sancho-Knapik, D., Sanz, M. Á., Peguero-Pina, J. J., Niinemets, Ü., & Gil-Pelegrín, E. (2017). Changes of secondary metabolites in Pinus sylvestris L. needles under increasing soil water deficit. Annals of Forest Science, 74(1), 24. (link to full text)

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A dying Scots pine in southern France following the 2003 European heat wave and drought (pic from here)

Abstract:

Key message

A multiphasic response to water deficit was found in Scots pine primary and secondary metabolism. First, an increase of terpenoids coincided with the stomatal closure. Second, an accumulation of proline, ABA, and shikimic acid was detected when photosynthesis was negligible.

Context

Drought-induced mortality is characterized by a major needle yellowing followed by severe defoliation and whole branch death. Before these external visual symptoms of drought stress take place, different alterations occur in plant metabolism.

Aims

This study aims to detect changes in primary and secondary metabolism of Pinus sylvestris L. in response to a decrease in soil water availability.

Methods

We analyzed needle water potential, photosynthetic characteristics, and concentrations of proline, terpenoids, shikimic acid, total polyphenols, and abscisic acid (ABA) in P. sylvestris through a 55-day soil water deficit period.

Results

Concentrations of most metabolites varied with the decrease in soil water availability, but changes in different compounds were triggered at different times, highlighting a multiphasic response. Increases in monoterpene and sesquiterpenoid content at moderate water deficit coincided with stomatal closure which preceded the accumulation of proline, ABA, and shikimic acid under severe water deficit when net photosynthesis was negligible.

Conclusion

This work confirms that most of the secondary metabolites under investigation in Pinus sylvestris did not increase until a moderate to severe water deficit was experienced, when photosynthesis was limited by stomatal closure.

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Guest post – Hannes Kollist about the emperor´s new clothes

Text by Hannes Kollist

<From the editor: Our good colleague Hannes Kollist, professor of Molecular Plant Biology and the PI of Plant Signal Research Group at University of Tartu, participated recently in EU high-level conference “Modern Biotechnologies in Agriculture – Paving the way for responsible innovation” and wrote down some of his reflections from that meeting. This text was originally published in the EU´s parliament magazine The Parliament (link to the original text).>

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Hannes Kollist (pic from here)

The Emperor’s new clothes

It’s neither wise nor safe for EU policymakers to dismiss new breeding techniques as ‘dangerous’ without any real consideration of the facts, argues Hannes Kollist.

Hans Christian Andersen’s celebrated tale has served as an admirable metaphor for deception since its publication in 1837. It tells the tale of an Emperor who unknowingly parades naked before his subjects in a new suit of imaginary clothes sold to him by two swindlers. The truth is only revealed after a small child cries out, “But he has nothing on.” The recent EU high-level conference on “Modern Biotechnologies in Agriculture – Paving the way for responsible innovation”, highlighted that 180 years on from Andersen’s classic tale, deception remains rampant.

EU Commissioner for Health and Food Safety, Vytenis Andriukaitis called the meeting to discuss whether new breeding techniques (NBTs) should be classified as conventional, and accordingly be left out from those regulations that are in force for genetically modified (GM) plants. We are talking about recently developed methods that enable controlled and precise gene-editing and have been already used to give plants desired properties, similarly to those encountered throughout evolution.

There is a major difference between NBTs and GM methods. Many of these techniques do not introduce foreign DNA and often the resulting organisms have just a single nucleotide change to their DNA sequence: something that readily happens every time a DNA strand is naturally replicated.

New gene editing technologies are already revolutionising every field in life sciences, from plant breeding to human medicine. Obviously, these technologies will be effectively used in plant breeding and benefit in finding ways to boost nutritious plant growth while helping to minimise pesticide use, thus perfectly assisting organic farming objectives.

But instead of discussing the conference’s agenda, roughly 300 respected experts gathered and spent an entire day discussing unproven risks and the need for labelling organisms where NBTs are applied.

One of the priorities of the Estonian Presidency of the European Union is the development of an open and innovative economy. And I was proud to listen to the welcome speech given by Estonia’s rural affairs minister Tarmo Tamm, where he clearly stated that in addition to conventional breeding, the EU needs research-based solutions that have the potential to speed up breeding in a sustainable manner.

It would not be wise nor would it keep anyone more safe if these new technologies are brushed off as ‘dangerous’ without any real consideration.

Nevertheless, we spent the day in Brussels discussing scientifically unproven myths and legends concerning GM plants and NBTs. “There is no monopoly for being green”, Andriukaitis said to a Greenpeace representative at the meeting. I fully agree, I am ‘green’ as well, whenever possible I eat local unprocessed food, I am a hobby shepherd, and I am convinced that biodiversity is something we should be concerned about, as it’s vital to mankind’s sustainable development.

However, concerning the campaign against NBTs there is no doubt that this is one of the biggest public lies currently circulating and I simply do not understand how it is possible that despite all the facts 300 experts gathered in Brussels and no one dared to say that the Emperor was actually naked.

We should consider whether we want Europe to become a History Theme Park show-casing a “Museum of Agriculture” or whether we should aim to increase Europe’s competitiveness and be part of the next green revolution, possibly triggered by new innovative plant breeding techniques that will be a key component of sustainable development.

The EU and its institutions are perhaps the best possible platform that can be used to achieve this.

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New paper published – Physiological and structural tradeoffs underlying the leaf economics spectrum

Text and graph by Tiina Tosens

In the world-wide leaf economics spectrum (Wright et al. 2004, Nature) variability of three key traits: photosynthesis rate, leaf nitrogen content, and leaf dry mass per area of 2500 species (from study sites with highly variable mean annual humidity and temperature) fall along the single axis of this three-trait space. However, the striking question has been what actually is the parameter that drives LES relationships. Meta-analysis (lead by Dr. Yusuke Onoda from Kyoto University) confirms the speculations that this variation is caused by variable mesophyll conductance (e.g. CO2 diffusion efficiency from sub-stomatal cavities to chloroplasts) and different life strategies in terms of nitrogen investment into structural cell wall material rather than photosynthetic biochemistry (see the figure below).

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Illustration of structure-function relationships of two species with contrasting life strategies. Left: temperate decidous pioneer species Populus tremula and right side: evergreen Cycas taitungensis. Mesophyll tissue, epidermis, scleroids and cuticle are shown. Populus tremula leaf is positioned to fast return end of LES.  Populus invests  proportionally less resources into protective cells (scleroids, cuticle, thick mesophyll  cell walls) rather it invests into building 2 layers of thick physiologically active palisade tissue this in turn brings to high photosynthesis and fast growth rate while Cycads have proportionally more C and N invested into protective structural cells and therefore lower photosynthesis and slower growth rate. However, in longer perspective Cycas has longer leaf life span and slower energy return. That is, more nitrogen invested into cell walls means more durable and tougher leaves. On the other hand thick mesophyll cell walls represent longer liquid phase distance through cell walls (low mesophyll conductance) into the chloroplasts and therefore less efficient photosynthesis

 

Citation: Onoda, Y., Wright, I. J., Evans, J. R., Hikosaka, K., Kitajima, K., Niinemets, Ü., Poorter, H., Tosens, T. & Westoby, M. (2017). Physiological and structural tradeoffs underlying the leaf economics spectrum. New Phytologist, 214(4), 1447-1463. (link to full text)

Check also out a commentary titled “Peeking beneath the hood of the leaf economics spectrum” by by Reich and Flores-Moreno (link to full text) who emphasize the significance of this study: “What is most novel about their study is the bringing together of considerable data on rarely measured leaf traits, assessing both chemical (e.g. nitrogen (N) allocation) and diffusive (mesophyll conductance) constraints at the same time, and identifying a key role for cell-wall thickness in both of these.

Abstract:

  • The leaf economics spectrum (LES) represents a suite of intercorrelated leaf traits concerning construction costs per unit leaf area, nutrient concentrations, and rates of carbon fixation and tissue turnover. Although broad trade-offs among leaf structural and physiological traits have been demonstrated, we still do not have a comprehensive view of the fundamental constraints underlying the LES trade-offs.
  • Here, we investigated physiological and structural mechanisms underpinning the LES by analysing a novel data compilation incorporating rarely considered traits such as the dry mass fraction in cell walls, nitrogen allocation, mesophyll CO2 diffusion and associated anatomical traits for hundreds of species covering major growth forms.
  • The analysis demonstrates that cell wall constituents are major components of leaf dry mass (18–70%), especially in leaves with high leaf mass per unit area (LMA) and long lifespan. A greater fraction of leaf mass in cell walls is typically associated with a lower fraction of leaf nitrogen (N) invested in photosynthetic proteins; and lower within-leaf CO2 diffusion rates, as a result of thicker mesophyll cell walls.
  • The costs associated with greater investments in cell walls underpin the LES: long leaf lifespans are achieved via higher LMA and in turn by higher cell wall mass fraction, but this inevitably reduces the efficiency of photosynthesis.
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Workgroup and EcolChange seminar – Joao Carlos Bespalhok about the production chain of sugarcane in Brazil

Seminar of Chair of Field Crop and Plant Biology and Centre of Excellence EcolChange

This week we have a quest giving seminar: professor Joao Carlos Bespalhok from the Universidade Federal do Paraná, Brazil. He´ll be talking about the biotechnological ways of processing sugarcane into other things than sugar…

Title of the talk: The production chain of sugarcane in Brazil: from plant to bioethanol

Time: Monday, 09. October 2017 at 10.00

Place: Tartu, Kreutzwaldi 5 – C25 (Metsamaja)

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Sugarcane fuel! (pic from here)

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Redwood forests through pinhole

Text and pics by Lauri Laanisto

Couple of months ago I attended 102nd annual ESA meeting in Portland, USA (link to conference page). After that we (my PhD student was attending as well) rented a car and drove couple of hundred miles south to visit coastal redwood forests in Northern California and Southern Oregon. In addition to redwoods, we saw huge sitka spruces, Darlingtonias, fern canyon, Crater lake, huge forest fires, whales and different marine ecosystems. It was quite an experience! Here is a selection of pictures that I took with my pinhole camera. If the pinhole camera is built into a matchbox – and mine is -, then it has a very wide angle. Which, of course, makes the trees significantly skinnier than they actually are. So, if anyone wants to see “normal” pictures more or less from the same places taken by smartphone, click this link here. (The text in that blog post is however in Estonian.) Although I must say that the majesty of these huge trees cannot be captured in pictures – at least we weren´t able to do it. You really have to be among them to get the “real picture”…

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Workgroup and EcolChange seminar – Valentina Zolotarjova about nonmetric multidimensional scaling

Seminar of Chair of Field Crop and Plant Biology and Centre of Excellence EcolChange

Valentina Zolotarjova is PhD student and junior research fellow in the Chair of Field Crop and Plant Biology. (Oh, FYI, we had a structural reform in the university and the former Department of Plant Physiology was renamed as the Chair of Field Crop and Plant Biology.)

Title of the talk: Introduction to NMS (Nonmetric multidimensional scaling)

Time: Monday, 02. October 2017 at 10.00

Place: Tartu, Kreutzwaldi 5 – C25 (Metsamaja)

 

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Comparison of nonmetric (left panel) and metric (right panel) systems (pic from here)

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EUCYS exhibition 2017 Tallinn

Text and pics by Linda-Liisa Veromann-Jürgenson

The 29th European Union Contest for Young Scientists (EUCYS) took place for the first time in Estonia. According to their webpage: “The European Union Contest for Young Scientists was set up at 1989 to promote the ideals of co-operation and interchange between young scientists. The Contest is the annual showcase of the best of European student scientific achievement.” Brilliant students from 38 countries presented their work. We saw very high level and clever solutions from high school students to serious problems. For example, Jasper Tootsi, a student from Tartu presented his research into screening galactosemia to prevent infant mortality from this rare but extremely serious disease.

Fig. 1. EUCYS

Fig. 1. Our corner of the Research Estonia exhibition booth

In concert with this event, there was an exhibition organized by Research Estonia on Sunday where PhD students from different Estonian universities and fields of research introduced their work. I was lucky enough to be invited to talk about the research I do in plant physiology as one of the young members of the top group in Estonia in this field.

Fig. 2. EUCYS

Fig. 2. Demonstrating the differences of leaves between plant groups

There was a lot of interest in our group’s research both from the public as well as the international students competing in EUCYS. I think the exhibition was a success.

Fig. 3. EUCYS

Fig. 3. Research Estonia’s very serious Sunday team measuring the muscle tone and elasticity of a Zamia plant. The plant was tense

EUCYS webpage: https://eucys2017.eu/

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