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Diagrammatic illustration of the process of Plant Molecular Farming (PMF). (Figure 1 from Ref. 5 below)

Diagrammatic illustration of the process of Plant Molecular Farming (PMF). (Figure 1 from Ref. 5 below)

Plant-Based Vaccines – A Great Idea

It’s been over 20 years since I introduced students in my plant sciences classes to the idea of using genetically-engineered plants (GMOs) as a source of edible vaccines.

Basically, the idea was that some crop plants could be genetically engineered to
produce vaccines in their edible parts, which could then be eaten when inoculations were needed.

I think it’s safe to say that one of the chief proponents of this idea, since the early 1990’s, has been Dr. Charles Arntzen.

When Dr. Charles Arntzen of Arizona State University visited Thailand in 1992, he was not expecting a moment of scientific “eureka” that would redirect his career. However, after observing a young Thai mother soothing her fussy infant with bits of banana, this plant molecular biologist was struck with an idea that is both startling and ingenious. What if, in addition to quieting her child, the mother could also administer a life-saving vaccine – in the banana?” (from Ref. 1 below)

(By the way, a recent review of plant-made pharmaceuticals by Dr. Arntzen – please see Ref. 2 below – is what prompted this post.)

–> Fast-Forward to 2016 –> Despite the scientific progress (e.g., see Ref. 3) and all the interest and excitement with regard to this idea (e.g., see Ref. 4) that existed nearly 20 years ago, to date, there is no commercially-available plant-based edible vaccine.

Why not?

Reality Bites….The Banana

Brilliant ideas are often tempered, even sometimes crushed, by reality. And such appears to be the case for edible vaccines.

By 2004, the cumulative number of antigens from pathogens of humans and/or animals successfully expressed in GMO plants had reached almost 50 (from Ref. 5 below). But, by then, the limitations of edible vaccines was also becoming evident.

These limitations included the following:

  • Effectiveness of plant-derived oral vaccines – The stability and immunogenicity of orally-delivered antigens from plants appears to be highly variable, often producing unsatisfactory results. Also, a related concern, especially from a regulatory point of view, is how to deliver a specific dose of vaccine.
  • Human risks – Oral ingestion of food containing antigens may elicit an immune tolerance. Also, there may occur adverse allergic reactions to plant-specific compounds in the edible vaccines.
  • Ecological risks – The risks from field-grown GMO plants expressing vaccine components are not fully known. For example, of serious concern is the potential contamination of non-GMO crop plants and/or wild plants by the “escape” from GMO plants of transgenes coding for antigens “into the wild” – typically via pollen.
  • Government approval – The regulatory obstacles to orally-delivered, plant-derived vaccines may, indeed, be insurmountable at the present time.
  • Social resistance to GMOs – The last, but by no means the least, concern is the anti-GMO attitude of many people, especially with regard to the ingestion of GMO crops.

    These problems have undermined interest from the vaccine industry, and unless financial incentives are found, serious work on edible vaccines will be likely be confined to research labs. But, even though much progress been made in research laboratories, the practical applications of edible vaccines in the “real world” may be up against seemingly overwhelming odds.

    In his own words, Dr. Arntzen explains why promoting the idea of edible vaccines was probably a mistake:

    As I have said in recent years that [the term “edible vaccine”] may have attracted attention in the plant biology realm, but it probably has been much more counterproductive in the traditional vaccine industry. I have come to regret coining the term. In my naiveté, I was ignoring the rigorous regulatory requirements that government agencies and the vaccine industry follow to give us today’s highly effective and wonderfully safe vaccines. I still believe that using plant tissue for low-cost delivery of unpurified (or partially purified) antigens, perhaps as a dry powder, is technically feasible for mucosal vaccination. I see progress in this direction for animal vaccines, which is needed.” (from Ref. 2 below)

    Still, There Is Hope Down On The “Pharm”

    Although it’s unlikely that plant-grown “edible vaccines” will ever be used as originally envisioned, the interest in plants as biosynthetic factories for human and livestock pharmaceuticals, including vaccines, is alive and well. (For example, please see Refs. 6 and 7.)

    The West Africa Ebola virus outbreak of 2014-15 is a good example. As described in a previous post, tobacco plants were used to make an Ebola therapeutic called ZMappTM. (See YouTube video below.)

    And, more recently, tobacco plants were again in the news as “anti-malaria drug factories”.

    With the 2012 FDA approval of plant-made pharmaceutical (PMP) Elelyso for human use, the stage is set for other forthcoming PMPs. So, the future looks bright for “pharming” after all.

    Down on the “Pharm” (Some companies producing biologics and vaccines made in GMO plants that are in clinical development.)

    1. Mapp Biopharmaceutical, Inc. – Using tobacco plants to make components of Ebola vaccine ZMappTM.

    2. Medicago – Making vaccines against viruses (e.g., influenza and HIV) using tobacco plants.

    3. Ventria Bioscience – Making human lactoferrin (VEN 100) in rice as treatment against antibiotic-associated diarrhea.

    4. Planet Biotechnology – Using plants to produce treatment of MERS coronavirus infection.


    1. Mandy, R. (2005) “Banana Vaccines: A Conversation with Dr. Charles Arntzen.”, Journal of Young Investigators, published online September 2005. (Full Text)

    2. Arntzen, C. (2015) “Plant-made pharmaceuticals: from ‘Edible Vaccines’ to Ebola therapeutics.” Plant Biotechnology Journal, Vol. 13, pp. 1013-1016; DOI:10.1111/pbi.12460 (Full Text)

    3. Walmsley, A. M. and C. J. Arntzen (2000) “Plants for delivery of edible vaccines.” Current Opinion in Biotechnology, Vol. 11, pp. 126-129. (Abstract)

    4. Langridge, W. H. R. (2000) “Edible Vaccines.”, Scientific American, Vol. 283, pp. 66-71. (Full Text – PDF)

    5. Arntzen, C., S. Plotkin and B. Dodet (2005) “Plant-derived vaccines and antibodies: potential and limitations.” Vaccine, Vol. 23, pp. 1753–1756.

    6. Yao, J., et al. (2015) “Plants as Factories for Human Pharmaceuticals: Applications and Challenges.” International Journal of Molecular Sciences, Vol. 16, pp. 28549-28565; doi:10.3390/ijms161226122 (Full Text)

    7. Liew, P.S. and M. Hair-Bejo (2015) “Farming of Plant-Based Veterinary Vaccines and Their Applications for Disease Prevention in Animals.” Advances in Virology, Vol. 2015, Article ID 936940; doi.org/10.1155/2015/936940 (Full Text)

    YouTube Video – How to grow an Ebola vaccine with a tobacco plant

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    Tags: ,

  • A Flowering Uber?

    Batman has the Batmobile.

    Dr. Who has the Tardis.

    Is it possible that the protein that triggers flowering in plants also has its own special transport vehicle?

    A paper from Prof. Hao Yu’s lab at National University of Singapore published in the 6 June 2016 issue of Nature Plants appears to support this idea. (Please see Ref. 1 below.)

    Before I tell you about this report, let me remind you that:

  • 1 In many plants, flowering may be regulated by photoperiod, that is, the relative lengths of day and night, over a 24-hr period.
  • 2 This photoperiod is sensed in the leaves of the plant, mediated by the photoreceptor phytochrome.
  • 3 When the plant experiences a flower-inducing photoperiod, the leaves produce a substance long-known as “florigen”, whose true identity was discovered only about 10 years ago (see Ref. 2 below), namely, FT protein.
  • 4 The FT proteins are then transported via the phloem to the shoot apical meristems (SAMs).
  • 5 At the SAMs, the FT proteins interact with specific transcription factors called FD proteins to activate floral identity genes, thus inducing flowering.

    Today’s paper (Ref. 1) has to do with step 4 above, namely, how FT proteins are transported from leaves to SAMs.

    Briefly, Yang Zhu and co-investigators present several pieces of evidence that are consistent with the idea that proteins, with the unwieldy name of “SODIUM POTASSIUM ROOT DEFECTIVE 1”, abbreviated NaKR1, mediate the phloem transport of FT proteins from leaves to SAMs.

    First, let me tell you that the NaKR1 protein has previously been shown to travel in the phloem and to be involved in the long-distance phloem transport of sucrose and also, perhaps, mineral nutrients such as sodium (Na+) and potassium (K+). And, interestingly, it was also previously shown than NaKR1 affects flowering time under certain conditions.

    Knowing all this, Zhu and co-workers (Ref. 1) found that the expression of the genes coding for FT and NaKR1 were similarly affected by photoperiod and by flowering-related genetic factors, and that the relative levels and cellular locations of both FT and NaKR1 coincided with each other.

    Moreover, “We provide evidence that NaKR1 interacts in vivo with FT, and promotes flowering by regulating long-distance movement of FT from leaves to the shoot apex through the phloem stream. Our results suggest that NaKR1 is a hitherto unknown regulator specifically required for photoperiodic control of long-distance delivery of florigenic signals.” (From Ref. 1 below)

    Although the evidence supports the idea that NaKR1 is important in long-distance phloem transport of the flowering signal (at least in Arabidopsis), it’s unclear exactly how it does so.


    1. Zhu, Y., L. Liu, L. Shen & H. Yu (2016) “NaKR1 regulates long-distance movement of FLOWERING LOCUS T in Arabidopsis.” Nature Plants, Vol. 2, Article number: 16075;
    doi:10.1038/nplants.2016.75. (Abstract)

    2. Corbesier, L., et al. (2007) “FT protein movement contributes to long-distance signaling in floral induction of Arabidopsis.” Science, Vol. 316, pp. 1030-1033; DOI: 10.1126/science.1141752 (Abstract).

    HowPlantsWork © 2008-2016 All Rights Reserved.

  • Land Plants Do Affect the Climate

    About 70% of the Earth’s surface is covered by oceans, and marine phytoplankton likely play a significant role in cloud formation via ice nucleation (and, thus, affect the weather and climate). For example, please see Ref. 1 below.

    But a paper published in 2015 (see Ref. 2 below) suggested that we have underestimated the impact of pollen from land plants on cloud formation. (A nice summary of this report: Pollen and clouds: April flowers bring May showers?)

    So this led me to wondering about the question of whether “macroscopic” land plants significantly affect the weather. (Let’s leave the microscopic phytoplankton for another time….)

    Of course, it follows that if 70% of the Earth’s surface is covered by oceans, then the remaining 30% is land. About 1/3 of the land is cold or hot desert (few or no plants). So, roughly speaking, about 20% of the Earth’s surface is covered with vegetation. And about half of this is forests. Thus, it’s not unreasonable to presume that terrestrial plants may affect the Earth’s climate (time frame = decades), and perhaps even the weather (time frame = minutes to months).

    It’s generally accepted that terrestrial ecosystems (especially forests) may have significant effects on the climate. (See, for example, forests’ roles in climate.) Terrestrial ecosystems influence climate by affecting how much solar energy is absorbed by the land surface and by exchanging climatically important gases with the atmosphere.

    But Do Land Plants Also Affect the Weather?

    I’m skeptical,…

    However, it is surprising how much plants affect weather. Plants process and release water vapor (necessary for cloud formation) and absorb and emit energy used to drive weather. Plants also produce their own micro-weather by controlling the humidity and temperature immediately surrounding their leaves through transpiration. Most plants and forest soils have a very low albedo, (about .03 to .20) and absorb a large amount of energy. However, plants don’t contribute to overall warming because the excess warmth is offset by evaporative cooling from transpiration.” (From the excellent website Vegetation: Its Role in Weather and Climate provided by North Carolina State University)

    I also found a good online resource for explaining the relationships between forests and weather (see Ref. 3 below) In it, the authors state that:
    “1. The main mechanisms by which forests modify weather have been identified. They are the surface albedo, transpiration and evaporation of water vapour, aerodynamic effects, and emission of hydrocarbons whose oxidation can form aerosol particles.
    2. Different mechanisms are dominant for each class of forest. Boreal forests affect local weather and climate via their low albedos, causing a local warming. Temperate forests modify weather via the albedo and transpiration of moisture, but their exact impacts on climate are the least certain. Tropical forests cool climate via their very high transpiration rates; the moisture transferred to the atmosphere forms large clouds which reflect incoming solar energy and cause a further cooling.”
    (from Ref. 3 below)

    And, if you consider seaweeds in the intertidal zone land plants, then:

    (1) Stressed seaweed contributes to cloudy coastal skies, study suggests and

    (2) Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry.

    …but now I think it’s safe to say that land plants do indeed affect the weather (at least under certain circumstances).


    1. Amos, J. (2015) Ocean plants ‘can help freeze clouds’, BBC News Online

    2. Steiner, A. L., et al. (2015) “Pollen as atmospheric cloud condensation nuclei.” Geophysical Research Letters, Vol. 42, pp. 3596–3602. doi: 10.1002/2015GL064060 (Abstract)

    3. Sanderson, M., M. Santini, R. Valentini and E. Pope (2012) “Relationships between forests and weather.” EC Directorate General of the Environment. Full Text (PDF)

    HowPlantsWork © 2008-2016 All Rights Reserved.

    By Emily Stackhouse [Public domain], via Wikimedia Commons

    By Emily Stackhouse [Public domain], via Wikimedia Commons

    Potatoes And Tomatoes And Deadly Nightshade

    Two recent reports (1) that potato plants boost the chemical defenses in their leaves when their tubers are under attack (see Ref. 1 below) and (2) Why Tomato Leaves Smell “Grassy”? (see Ref. 2 below) reminded me of how fascinating the biochemistry is in solanaceous plants and, also, of a question I sometimes got when I was a botany professor.

    Is it safe to eat green potatoes?

    This question, I presume, was prompted by articles such as “Horrific Tales of Potatoes That Caused Mass Sickness and Even Death”.

    Potatoes and tomatoes are the most well-known members of the plant family Solanaceae, a.k.a., the nightshade family.

    Perhaps the most notorious member of this family, “deadly nightshade” (Atropa belladonna), is very toxic, even deadly.

    (By the way, a really good book about this and other poisonous plants is Wicked Plants: The Weed That Killed Lincoln’s Mother and Other Botanical Atrocities, which was featured in a previous post.)

    So, is it any wonder that people would expect the foliage of potatoes and tomatoes to also be very toxic?

    And, indeed, both tomato leaves and potato tubers that have turned green due to exposure to light contain relatively small amounts of toxic compounds called alkaloids.

    But according the “Curious Cook”, a.k.a., Harold McGee, the author of several books on the science of cooking (shown below), we may not have to worry too much about this.

    Please see the links below for why:

    Harold McGee on eating tomato leaves.

    Harold McGee on green potatoes.

    Though I wouldn’t eat a bunch of green potatoes, I may try a few tomato leaves in my next batch of pasta sauce.

    Thanks Curious Cook!

    Books by Harold McGee:

    The classic that every cook should own: On Food and Cooking and, more recently, The Curious Cook.


    1. Kumar, P., E. V. Ortiz, E. Garrido, K. Poveda, and G. Jander (2016) “Potato tuber herbivory increases resistance to aboveground lepidopteran herbivores.” Oecologia, doi: http://dx.doi.org/10.1007/s00442-016-3633-2 (Abstract)

    2. Kunishima, M. et al. (2016) “Identification of (Z)-3:(E)-2-hexenal isomerases essential to the production of the leaf aldehyde in plants.” Journal of Biological Chemistry, doi: 10.1074/jbc.M116.726687 (Abstract)

    HowPlantsWork © 2008-2016 All Rights Reserved.

    Pk16 clip image004Here, There, and Everywhere?

    Recent headlines – China to acquire Syngenta and Chinese farmers are illegally growing GMO corn: Greenpeace – got me wondering about the proliferation (or lack of it) of GMO crop plants outside the USA.

    It’s seems well-known that biotech crops are not welcome in most of Europe. But what about the rest of the world?

    As mentioned in a previous post, some countries have banned GMOs, including most of the EU countries, Russia, Philippines, Saudi Arabia, Egypt, and Tasmania (see here for a list of 36 countries that have banned the cultivation of GMO crops).

    However, as shown in the table on the right (from: Ref. 1 below), a number of other countries all around the world have indeed been actively engaged in cultivating GMO crops.

    Please see the references below – with a particular emphasis on China – for current information regarding this topic.


    1. James, C. (2014) “Global Status of Commercialized Biotech/GM Crops: 2014.” ISAAA Brief No. 49. ISAAA: Ithaca, NY. (Full Text – PDF)

    2. Talbot. D. “China’ GMO Stockpile“, MIT Technology Review online, October 21, 2014.

    3. Larson, C. “Can the Chinese Government Get Its People to Like G.M.O.s?“, The New Yorker online, August 31, 2015.

    4. Li, Y., Y. Peng, E. M. Hallerman, and K. Wu (2014) “Biosafety management and commercial use of genetically modified crops in China.”, Plant Cell Reports, Vol. 33, pp. 565-573. (Abstract).

    5. Li, Y., E. M. Hallerman, Q. Liu, K. Wu and Y. Peng (2015) “The development and status of Bt rice in China.” Plant Biotechnology Journal, doi: 10.1111/pbi.12464. (Full Text)

    6. Thomson, J. A. (2015) “Why genetically modified crops have been slow to take hold in Africa.” The Conversation, published online July 13, 2015. (Full Text).

    7. Kumar, S. (2015) “India eases stance on GM crop trials.” Nature, Vol. 521, pp. 138-139. (Full Text)

    HowPlantsWork © 2008-2016 All Rights Reserved.

    Tearing Down The Paywalls?

    Over the years scribbling this blog, I’ve often been frustrated when trying to provide readers with links to material I’ve referenced. This is because, in many cases, the scientific information in question has been published in a journal article that is blocked by a paywall.

    But just like with newspapers and magazines, the world of scientific journal publications has dramatically changed in the past 10 years.

    Frustration with blocked online-access to scientific papers, the majority of which were the result of publicly-funded research, led many people, including scientists, to demand that publishers provide less restrictive access.

    Bowing to this outcry (and likely fearing legislation requiring free access to publicly-funded research results), many publishers responded by providing partial open-access options to authors (for a fee, of course).

    Alternatively, some scientists (and even some publishers) established fully open-access scientific journals, where authors could publish peer-reviewed scientific research free to view on the Internet. (In most cases, authors are charged a “publication fee” that varies from several hundred dollars to several thousand dollars.)

    You may have noticed that almost everything involved with the Internet these days seems to be in a constant state of flux. And scientific publication on the Internet is no exception (see Addendum below, for example).

    But since I don’t have the time or space here to cover all the myriad of ways one can publish scientific information these days, please allow me to offer you a few tidbits.

    What is meant by: Open Access (Wikipedia)

    For your perusal: a Directory of Open Access Journals

    Some recent news: Handful of Biologists Went Rogue and Published Directly to Internet

    And, of course, we can’t forget Caveat emptorPredatory publishers are corrupting open access, and be sure to check potential open-access journals at the great website Scholarly Open Access.

    Here’s my list – in no particular order – of full open-access plant science journals*:

    *Please note, this list is biased. These journals tend to feature articles in the realms of plant physiology and/or plant molecular biology, because, after all, this blog is about how plants work.

    For each journal, I’ve included the year of first publication, relative ranking (citations), publisher information, and publication fee. (Please also see legend below for further explanation.) Also, I may have missed a journal or two (or even more than two), so please leave a comment if I’ve overlooked your favorite open-access plant science journal.

  • AoB Plants (0,624) [16] (Oxford) 2010 {$1,000}
  • International Journal of Plant Biology (0,107) [5] 2010 {$560}
  • Frontiers in Plant Science (1,552) [36] 2007 {$2,490}
  • Applications in Plant Science* [6] (Botanical Society of America) 2013 {$1,200}
  • Current Plant Biology* (Elsevier) 2014 {$2,000}
  • Plant Biotechnology Journal (2,034) [51] (Wiley) 2003 {$2,720}
  • PLOS ONE – Plant Science [161 for PLOS ONE] 2006 {$1,495}

    ( ) = SJR Journal Rankings – Plant Science – 2014 (* indicates journal likely too new for ranking)

    [ ] = Google Scholar Metrics value

    { } = publication fee (Please note: actual fee may differ depending on various factors, such as society membership, type of publication, type of open access, etc.)

    Partial Open-Access Plant Science Journals

    To be fair, I should also mention that some plant science journals now offer authors the option to publish open-access articles (typically, for a publication fee). However, journals published by scientific societies, such as the ASPB and BSA, discount (even waive) this fee if the corresponding authors are members of the society or if their institution subscribes to the journal (please see Ref. 1 below, for example).

    I’d like to highlight the journal Plant Physiology in this regard. If the corresponding author is a member of the ASPB, then there is no publication fee to make the paper fully open-access. A brief accounting of the number of fully open-access papers published in 2015 for this relatively high-impact plant science journal (please see here, for example) revealed that the majority of the published papers were fully open-access articles. Thanks Plant Physiology!

    Addendum: Different Categories of “Open-Access”

    Apparently there exists at least two levels of “open-access”, so-called “gold” and “green”.

    I’ll leave it to the Nature Publishing Group to define:

    Gold open access:

    “Article is made open access immediately on publication.
    Usually associated with an Article Processing Charge (APC).
    Article is freely available on our platform.
    Article is the version of record, i.e. publisher’s typeset PDF.
    CC BY licence allows unrestricted reuse of the article providing the author(s) and original source are properly cited. CC BY is the default license for all NPG-owned fully open access titles. Other licences are available.”

    versus, Green open access:

    “Open access after an embargo period (though an embargo will not apply in all cases).
    Article is made freely available but somewhere other than the publisher’s website, e.g. in a subject or university repository, or the author’s homepage.
    Open access article is not necessarily the version of record – it could be the typeset PDF or the author’s final version after peer review but before typesetting.
    Rights/re-use may be limited.”

    Update: E.U. urged to free all scientific papers by 2020

    In Related News:
    Springer Nature to extend content sharing to whole Springer Nature-owned journal portfolio

    Who’s downloading pirated papers?…Everyone!


    1. Ort, D. (2006) “RT-Plant Physiology: Full Open Access Publishing at No Charge to ASPB Members” Plant Physiology, Vol. 142, p. 5. (Full Text)

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  • GMO? OMG!

    Back in the day, I used to be a member of the American Society of Plant Physiologists (ASPP), which morphed into the American Society of Plant Biologists (ASPB) in 2001 to better reflect the diverse fields of plant science (read “plant molecular biology”) emerging in the 21st century.

    Anyway, I noticed that the ASPB was recently in the news because of a petition it sponsored (which has been signed by well over 1,500 scientists, to date) supporting GMO technology for crop improvement.

    The petition has been generally perceived as a warning to the anti-GMO folks that they are hindering the next Green Revolution presumably needed to feed the 9.6 billion people that’ll likely be on this planet in about 35 more trips around the sun (that is, in 2050).

    Despite the preponderance of scientific evidence in favor of GMO crops (see here, here and here, for example, and also Refs. 1 & 2 below):

  • Some countries have banned GMOs, including most of the EU countries, Russia, Philippines, Saudi Arabia, Egypt, and Tasmania (see here for a list of 36 countries that have banned the cultivation of GMO crops).
  • Recent polls indicate that over 50% of Americans think that it’s unsafe to eat genetically modified foods.

  • Last year, Chipotle declared it was the first national restaurant chain to cook with only non-GMO ingredients (although this claim has been challenged).

    An Unconscious Decision?

    Despite the overwhelming scientific evidence in favor of the safety and efficacy of the use of plant genetic engineering for crop improvement, there exists strong public opposition to GMO’s. This opposition has motivated some companies to ban GMO-derived ingredients from their products and some countries to ban, or significantly limit, the cultivation of GMO crops (see above).

    The seemingly irrational, yet strong, objections to GMO crops has long frustrated many members of the plant science community, which presumably motivated the ASPB to sponsor its petition supporting GMO technology.

    This frustration has recently led some plant biotechnologists to collaborate with cognitive scientists in order to understand WHY there is such widespread opposition GMO’s despite the scientific evidence to the contrary.

    This collaboration resulted in a paper published last year (see Ref. 3 below) that concluded that human emotion, not reason, was why arguments against GMO’s had such resonance with the general public. They found that the human mind may be highly susceptible to negative, and frequently emotional, arguments by opponents of GMOs.

    According to the lead author of the paper Stefaan Blancke: “Negative representations of GMOs–for instance, like claims that GMOs cause diseases and contaminate the environment–tap into our feelings of disgust and this sticks to the mind. These emotions are very difficult to counter, in particular because the science of GMOs is complex to communicate.” (from: Psychology of the appeal of being anti-GMO).

    So I guess it’s no big surprise that in the case of public opposition to GMO crops, emotions often trump reason (like so many other things in life).

    Please Note: Don’t get me wrong. As discussed in a previous post, there are some rationale reasons to seriously question some GMO’s, including economic, political and ecological arguments.


    1. Klümper, W. and M. Qaim (2014) “A Meta-Analysis of the Impacts of Genetically Modified Crops.” PLoS ONE, 9(11): e111629. doi:10.1371/journal.pone.0111629. (Full Text)

    2. Nicolia, A., A. Manzo, F. Veronesi and D. Rosellini (2013) “An overview of the last 10 years of genetically engineered crop safety research.” Critical Reviews in Biotechnology, Vol. 34, pp. 77-88. (Abstract)

    3. Blancke, S., F. Van Breusegem, G. De Jaeger, J. Braeckman, and M. Van Montagu (2015) “Fatal attraction: the intuitive appeal of GMO opposition.” Trends in Plant Science, Vol. 20, pp. 414-418. (Abstract)

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  • Cover tifWhy Do Flowers Smell?

    A couple of the most common questions that people have about flowers are: (1) Why do flowers have scents? and (2) Why do many flowers smell good to us?

    The first question is fairly easy to answer, but the second one is a bit trickier to try to answer.

    The short answer to “Why do flowers smell? is: because floral scents help to attract pollinators. A more detailed answer to this question is provided courtesy of Scientific American online: Why do flowers have scents?

    As to why some flowers smell good to us, a reasonable answer has been provided by the Smithsonian.com: Why do flowers smell good?

    However, there is certainly a lot of speculation out there regarding this question. And I was able to find only one recent paper regarding peoples’ physiological responses to floral scents (please see Ref. 1 below).

    And don’t forget, some flowers smell absolutely terrible to us, especially ones that are pollinated by flies that are attracted to rotting flesh (carrion) and animal feces. (Please see, for example, Stinking Flowers – Not All Flowers Smell As Sweet As A Rose.)

    Currently, my own personal favorite is the following: Orchids give off human ‘body odor’ to attract mosquitoes.

    Anyway, what got me interested in this subject at the present time is a recent opinion piece in the journal Trends in Plant Science (see Ref. 2 below).

    In this article, the authors discuss four basic suppositions:

  • Plants emit volatile organic compounds that can function as cues to other plants.
  • Plants may use floral volatiles from their neighbors to sense their mating environment.
  • Plants could respond by adjusting floral traits that affect pollination and mating.
  • Plant responses to floral volatiles cues are particularly likely to be adaptive.
  • (from Ref. 2 below)

    In other words, volatile organic compounds produced by some flowers provide a complex array of chemical signals that may be detected by neighboring plants and that, in turn, may influence their reproductive physiology.


    1. Jo, H., et al. (2013) “Physiological and Psychological Response to Floral Scent.” HortScience, Vol. 48, pp. 82-88. (Full Text).

    2. Caruso, C. M. and A. L. Parachnowitsch (2016) “Do Plants Eavesdrop on Floral Scent Signals?” Trends in Plant Science, Vol. 21, pp. 9-15. (Abstract)

    HowPlantsWork © 2008-2016 All Rights Reserved.

    From “Smart” Plants to “Resurrection” Grass

    Last month’s plant science news featured many familiar topics from 2015, including plant-microbe interactions and the effects of increased atmospheric CO2 on plants.

    But perhaps the most interesting story from December 2015 involved a new theory from Princeton University biologists regarding the notion that “…ecosystems of the world take their various forms because plant “decisions” make them that way.”

    One of the current “big” questions in plant biology is how the increased atmospheric CO2 that has occurred in the past century has affected plants, if at all. A report published last month provided a very interesting assertion.

    Why have seed plants been so successful at spreading around the world? The answer, dear reader, may be “wax”.

    When I was a professor in the Biology Department at Montana State University in the mid 1980’s, a colleague in the Plant Pathology Department, Prof. Gary Strobel, created quite a kerfuffle by attempting to combat Dutch elm disease by injecting young elm trees with genetically-altered bacteria, which, it turned out, was an unauthorized experiment at the time. When Stobel voluntarily (and somewhat dramatically) halted his experiments, this became national news.

    Fast-forward nearly 30 years…there has been little, if any, subsequent evidence published that supports Strobel’s idea (see here, for example). But a new report published last month suggests that there may exist another potential biocontrol agent.

    There are some plants, sometimes called “resurrection plants”, that can “come back to life” after nearly completely drying out. How can they do this? Some Australian scientists may have some clues to this mystery.

  • It’s easy to think of plants as passive features of their environments, doing as the land prescribes, serving as a backdrop to the bustling animal kingdom. But what if the ecosystems of the world take their various forms because plant “decisions” make them that way?Theory of ‘smart’ plants may explain the evolution of global ecosystems.
  • Swedish plant scientists “…have discovered that increasing levels of carbon dioxide in the atmosphere have shifted photosynthetic metabolism in plants over the 20th century. This is the first study worldwide that deduces biochemical regulation of plant metabolism from historical specimens.Has increased carbon dioxide altered the photosynthesis of plants over the 20th century?
  • Having emerged late during evolution, seeds have transformed many plants into miniature travelers, contributing greatly to their colonization of terrestrial habitats. Researchers at the University of Geneva (UNIGE), Switzerland, have just discovered one of the keys to this success: the cuticle.A wax shield to conquer the Earth.
  • According to a research of UPM along with other five European research centres, health of some elm trees could be related to the endophyte flora that inhabits inside these trees.Endophytic fungi in elm trees help protect them from Dutch elm disease.
  • A native Australian grass that “plays dead” during droughts and selectively culls its own cells to survive could provide genetic keys to help world food crops like chickpea withstand global climate change.Back from the “Dead” – Scientists unlock the secrets of “resurrection” grass.

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  • From Sexy Mushrooms to Electric Algae

    The rains of November help to bring out the mushrooms in the forests of North America. And, fittingly, one of the most popular plant-related stories of November 2015 was a tale of “Sex, death and mushrooms”.

    According to a report published last November, wheat “…provides a fifth of global caloric intake.” And “Estimates put potential losses from wheat rust diseases in Australia alone at more than one-and-a-half billion dollars each year.” So, it wasn’t surprising that a paper, published late last year, announcing the identification of a key wheat disease-resistance gene attracted a lot of interest.

    I’ve long believed that most people underestimate the importance of plants. But some people also believe that plants possess some sort of innate “intelligence”. What do you think? The BBC weighed in on the subject last November…..

    Are algae plants? According to one botanical webpage: “Most algae are traditionally considered as a plant subkingdom within the 5-kingdom classification. The diagnostic characters of the algal group as a whole were ill-defined, but nevertheless vastly different from the well-defined traits of the other two plant subkingdoms, namely the bryophytes and vascular land plants. Other biologists who were convinced that not all algae are plants revised the classification, preferring algae to be placed in Kingdom Protista, with only some multicellular phyla, particularly the Chlorophyta, Rhodophyta and Phaeophyta, remaining as plants. Then there were other biologists who regarded some of these multicellular forms to be placed in Kingdom Protista. The result was, and still is confusion.

    Anyway, however you consider algae, they were in the plant news several times in November 2015.

  • The unpredictable flowering of beautiful alien forms from rotting wood, dung or leaf litter in a forest moving toward winter is a strong and strange conjuration of life-in-death — in Baltic mythology, mushrooms were thought to be the fingers of the god of the dead bursting through the ground to feed the poor.Sex, death and mushrooms.
  • An international team of scientists has identified a gene that can prevent some of the most significant wheat diseases-…Wheat disease-resistance gene identified, potential to save billions.
  • Research suggests plants might be capable of more than we suspect. Some scientists – controversially – describe plants as “intelligent”.Do we underestimate the power of plants and trees?
  • Scientists from the John Innes Centre, the universities of Cambridge and Edinburgh and Stanford University in California, have shown that genes from an alga which is capable of very efficient photosynthesis can function properly when introduced into Arabidopsis, a plant commonly used for scientific experiments.New progress towards maximising photosynthesis in plants.
  • To limit climate change, experts say that we need to reach carbon neutrality by the end of this century at the latest. To achieve that goal, our dependence on fossil fuels must be reversed. But what energy source will take its place? Researchers from Concordia just might have the answer: algae.Harnessing the electrical energy from plants – Algae could be new green power source.
  • Next-Time: Wrapping up the 2015 plant news retrospective….

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