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Logo of annbotAboutAuthor GuidelinesEditorial BoardAnnals of Botany
 
Ann Bot. 2016 August; 118(2): iv–vii.
Published online 2016 July 28. doi:  10.1093/aob/mcw156
PMCID: PMC4970374

Plant Cuttings

The 21st century Prometheus

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The full title of Mary Shelley’s acclaimed 1818 novel “Frankenstein” [1] is “Frankenstein, or the Modern Prometheus” [2,3]. Well, fictional frightening-fellow fabricator Dr Frankenstein may have been the modern Prometheus of his day, but I’ve just chanced upon the 21st century version. Nothing to do with hard-copy science fiction of the late Georgian period, this truly modern Prometheus is science fact-based and exists virtually as an on-line Wiki (“a server program that allows users to collaborate in forming the content of a Web site” [4,5]). As befits the current obsession with initialisms[6], this Prometheus is a sort of acronym [7,8] that stands for PROtocols, METHods, Explanations and Updated Standards in ecological and environmental plant physiology[9]. Launched in 2010, it is ‘A unique web resource for physiology, ecology and the environmental sciences’[10]. Its four main categories are Sensing and environment, Structure, Function, and Experimental design and analysis, with each having several sub-categories and still lower level categories that contain the promethean items of the wiki’s name. To illustrate how this categorisation works – and in an attempt to boost a technique that is simple to use, requires little specialist equipment, is cheap, and can generate a tremendous amount of in-sight [you’ll see why I’ve chosen to present that word in this way shortly – I hope…] into plant biology – let’s look in more detail at the Structure category. Its four sub-categories are Anatomy and Microscopy, Architecture, Morphology, and Reproductive traits. Entering the first of those (well, what did you expect from one who is officially described as Senior Lecturer in Physiological Plant Anatomy..?), we have a summary of the microscopic techniques by Contributing Editors Brendan Choat[11] and Steven Jensen[12], and the list of lower level topics: Anatomical image analysis, Anatomical sectioning, and Tissue preparation, fixation, and embedding. Entering the second of those we reach the Protocols area, currently eight in total. Choosing ‘Making hand sections without support material’ we have detailed instructions for obtaining sections of plant material just using a double-edged razor blade, contributed by Rosemary White[13]. And – usefully! – photomicrographs that reveal what can be achieved by this basic procedure (and one of which shows lateral roots ‘trapped’ within the cortex of an aerenchymatous rice root – is this a first sighting of this phenomenon??). * There’s lots more to explore and discover (whether you’re into plant microstructure or other things!), but I’d thought I’d give this particular technique an airing since it is a great way to get students looking at plant anatomy and making their own discoveries – and is great for student projects… And, remember, they are the first person ever (ever, ever!) to have looked at that particular piece of plant that they’ve sectioned with their own razor-assisted hands! What better thrill is there in botany than that? Anyway, since this was a new discovery for me, I’d thought it might also be unknown to some of this column’s readers, hence this mention. It’s certainly a site that’s well worth exploring to see what useful protocols or methods might be there for your own exploitation (and which are free to use), or for you to consider supplementing with your own words of wisdom. It’s not the only free site that offers protocols, etc.,** but at least it’s one of the few dedicated to plant science so ought to offer more appropriately tailored solutions to your methodolobotanical queries.

*To further promote this technique, do also look at Peterson et al.’s Teaching plant anatomy through creative laboratory exercises[14], Kraehmer and Baur’s Weed Anatomy[15] and Yeung et al.’s Plant Microtechniques and Protocol[16].

**Others that readily come to mind are Nature Protocols[17], Protocol Exchange[18], BMC Plant Methods [19], and Springer Protocols[20].

Biomineralised barbed botanics bite back!

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Generally, plants don’t have the ability to run away if threatened by organisms that would cause them harm, e.g. by eating them. However, that doesn’t mean that they are defenceless in the face of such feeding attempts. Indeed, they are often armed with an impressive cocktail of chemicals that help to deter those who would dine upon their tasty tissues (e.g. [1,2]). And they also have an awesome armoury of surface-mounted hairs, prickles, thorns, spines, trichomes[3,4], and other enations[5] that deter all but the most determined of herbivores. Now, adding to this seriously hardcore catalogue of defences is the announcement by Hans-Jürgen Ensikat et al. that some plants are fighting back with added ‘bite’[6]. Studying members of the Loasaceae (the rock nettle family[7,8]) with electron microscopy and elemental analysis techniques, the team found that the cell walls of the tips of the stinging hairs and hooks of glochidiate trichomes of five species of the genus Loasa[9] contain nanocrystalline apatite-cellulose composite material. This apatite – a form of calcium phosphate[10,11] – is similar to the material found in animal teeth and bones of vertebrates[12,13], but is the first report of this form of biomineralisation in higher plants. Its presence in these defensive structures appears to reinforce the stinging hairs thereby helping them deliver the necessary ‘message’ – a painful sting from chemicals injected into the animal by the hypodermic nature of the stinging hair whose tip is broken off by contact with the animal. Ouch! However, arguably even more ingenious, is the news that other plants are very economical in their defence capabilities in using an environmentally produced coating. Examining naturally sand-coated Abronia latifolia (the aptly named sand verbena[14]) and plants of Navarretia mellita[15] supplemented with a sandy layer, Graduate Student Eric ‘Rick’ LoPresti and Prof. Richard ‘Rick’ Karban (University of California at Davis (USA), Department of Entomology and Nematology[16]) conclude that this mineral mantle has a protective role because such plants are less chewed by herbivores than those that are not so adorned[17]. They further deduce that it is a physical effect rather than one of camouflage whereby the plants are hidden from a herbivore’s sight by blending in as part of the sandy background. So, consumption-confounding psammophory (‘sand-carrying’[18]) is apparently not ‘cryptic’[19]. Importantly, this elegant study is the first experimental support for the hypothesis that a sand covering protects plants from herbivory.* And, why waste expensive and valuable resources on creating armour-coating when it’s provided by Mother Nature? Non-intelligent plants? I think not!

* However, listed in Norbert Jürgens’ review of the psammophorous species of southern Africa[20] is approx. eight potential roles for this phenomenon in the life of plants. So, there’s clearly more to examine in the intriguing lifestyle of these botanics that really show ‘true grit’ in surviving in some of the planet’s harshest environments.

369,400…and counting(!)

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Being an avid supporter of the importance of plants (I do hope that’s come over quite strongly in my various news items..?), I’m always keen to share with my students [well, any- and everybody really…] how many plant species there are. For several years the best – i.e. biggest! – number I’d found was 352,000 species of flowering plants[1]. Although officially an estimate, it’s quite impressive. However, the most up-to-date tally is 369,400 angiosperm[2] species (RBG Kew (2016) The State of the World’s Plants Report – 2016[3]).* But, and regardless of how many there are,** why should we be interested in all – or indeed any – plants anyway? Well, directly (e.g. as food for humans) or indirectly (as food for the animals whose flesh and/or other products we humans eat), plants are essential to keeping people alive. But they contribute so much more than that. That same Kew Report states that 31,128*** plant species currently have documented uses[4], over half (19,192) of which are used ‘socially’ or medicinally, more than a third have a materials use, and 9,187 are exploited as food for humans and other animals.**** All of that’s on the positive side for plants. On the negative side, 21 % of global plant species are currently threatened with extinction according to IUCN Red list criteria[5], i.e. are in the Vulnerable, Endangered, or Critically Endangered categories[6,7,8]. And – maybe surprisingly – almost a third of that risk is because of conversion of land for agriculture[9]. Which basically means that, if we are to have any chance of studying the plant diversity that exists (or is estimated so to do), we need to work to conserve the habitats wherein plants live (i.e. look after this planet a whole lot better than we’re doing at present! Now there’s a novel notion…). There’s a lot more in the Kew Report than what I’ve cherry-picked [10] above (but best to do so whilst there are still cherries left to pick…), so do download your own copy – it’s free – and find your own reasons to be cheerful, or scare yourself to sleep with its somewhat depressing statistics.

*Or 390,900 vascular plants (which includes angiosperms, gymnosperms[11], ferns[12] and fern-allies[13], but excludes the bryophytes[14,15] amongst the Kingdom Plantae[16,17]). But, if that’s too many species and too much information, remember that, according to Dr Markus Eichhorn, forest ecologist at The University of Nottingham, UK[18], all of this bewildering phytobiodiversity can be reduced to only four kinds of plants: Plants you can eat, Plants you can kill people with, Plants you can use to get high, and The rest[19].

**And don’t forget, that this is still many fewer than the 386,500 species of beetles on the planet (Slipinski et al.[20])! Now, it may be the case that ‘the Creator has an inordinate fondness for these insects’ (a quote attributed to JBS Haldane – British geneticist, biochemist, professor and writer[21,22]) over plants because of the multilegged animals’ numerical taxonomic superiority. However, might it not be the case that God, in her infinite wisdom, actually created many more plant species than beetles but chose to hide them in places so that we might not discover all of those extremely useful organisms until we had learnt to look after them..? If that’s the case, apparently the most likely hiding places are Brazil, Australia, and China[3]. However, if there are really 450,000 flowering plant species – as Stuart Pimm and Lucas Joppa suggest[23] – it’s Plants 1: Beetles 0… [Ed. – all of this numerical nonsense is trumped by the estimated 1 trillion (i.e. 1012) species of microbes on the planet anyway[24]. So, all bets are now off!]

***Interestingly, if you add up the number of species in each of the 10 categories that are listed, you get a total of 59,029, which gives an indication of how many plants have multiple uses. Somewhat irritatingly, though, I couldn’t find a list – or reference to a source that contains the list – of all of those (or indeed any of them by name!) species and what they are used for…

****I.e. plants keep us healthy and cheerful, clothed, and fed. Which trio of testamentary tracheophyte truths is reminiscent of the three words ‘Miserable’, ‘Naked’, and ‘Hungry’ that Prof. Armstrong[25] displays on the ‘board’ to start his classes in economic botany[26], and which is what us humans would be without plants.

Image: Wikimedia Commons

[1] Alan Paton et al., Taxon 57: 602–611, 2008; http://www.jstor.org/stable/25066027

[2] http://tolweb.org/Angiosperms/20646

[3] http://science.kew.org/strategic-output/state-worlds-plants

[4] https://stateoftheworldsplants.com/useful-plants

[5] http://www.iucnredlist.org/

[6] Neil Brummitt et al., PLoS ONE 10(8): e0135152. doi:10.1371/journal.pone.0135152

[7] http://www.threatenedplants.myspecies.info/

[8] http://www.kew.org/science-conservation/research-data/science-directory/projects/sampled-red-list-index-plants

[9] https://stateoftheworldsplants.com/extinction-risk

[10] http://idioms.thefreedictionary.com/cherry-pick

[11] http://www.conifers.org/zz/gymnosperms.php

[12] http://creationwiki.org/Fern

[13] https://en.wikipedia.org/wiki/Fern_ally

[14] http://www.theplantlist.org/1.1/browse/B/

[15] http://www.rbge.org.uk/science/cryptogamic-plants-and-fungi/bryology

[16] http://waynesword.palomar.edu/trmar99.htm#plantae

[17] http://www.fossilmuseum.net/Tree_of_Life/KingdomPlantae.htm

[18] https://www.researchgate.net/profile/Markus_Eichhorn

[19] https://treesinspace.com/2016/05/23/the-four-types-of-plants/

[20] http://www.mapress.com/zootaxa/2011/f/zt03148p208.pdf

[21] http://www.biography.com/people/jbs-haldane-37847

[22] https://en.wikiquote.org/wiki/J._B._S._Haldane

[23] Annals of the Missouri Botanical Garden 100(3):170-176, 2015; doi: http://dx.doi.org/10.3417/2012018

[24] Kenneth Locey and Jay Lennon, PNAS 113: 5970–5975, 2016; www.pnas.org/cgi/doi/10.1073/pnas.1521291113

[25] Professor of Botany at Illinois State University, USA – http://www.botany.org/Profiles/Joseph_Armstrong.php

[26] https://aobblog.com/2011/07/appealing-botany/#comment-2323

Fillyphyllophilia…

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We like plants-and-people stories in the Plant Cuttings collections – especially those that demonstrate the benefits of Man’s association with our vegetable co-habitants of planet Earth. We also like slightly unusual tales, too. This item delivers on both scores. Firstly this is a nice study whose main message is elegantly summarised thus: ‘Women in the U.S. who live in homes surrounded by more vegetation appear to have significantly lower mortality rates than those who live in areas with less vegetation, according to a new study’[1]. That new study – of 108,630 women in the USA – by Peter James et al.[2] demonstrates that those living in the greenest areas (chlorophyll levels were determined by a satellite image-based vegetation index) had a ‘12% lower rate of all-cause non-accidental mortality’. Although the team acknowledge that more research is required to determine the nature of this relationship between other natural environments and health, the results do at least show that green vegetation has some ‘protective effect’ on humans. Well, at least for the study’s cohort, who were primarily white non-Hispanic women of normal weight, but with low levels of physical activity living in metropolitan areas of the USA. However, Mr Cuttings suspects this green advantage can be found for all peoples – even men – but is enough of a scientist to acknowledge that we ought to await evidence-based reports before we can conclude that definitively. The second part of this item is an article by McGill University (Canada)’s Faculty of Dentistry member Louis Z. G. Touyz[3,4] and presents his musings on the role of trees and their relationship to human health, in particular oral health and human teeth[5].* Amongst the items covered is the importance of ‘oral biofilms’ (‘three-dimensional structured bacterial communities … embedded in an exo-polysaccharide matrix’[6]) that can develop on teeth.** This malevolent microbial mantle contributes to several dental problems such as removal of calcium from the mineral hydroxyapatite[7], which comprises >95% of enamel (the hard protective outer layer of the tooth[8]), and the diseases gingivitis (‘gum disease’) and periodontitis (a condition affecting the tissues and bone that support the teeth, and which can develop from gingivitis[9]). A plant-related way of removing this bacterial build-up – revealed to me in Touyz’s paper – is the oral hygiene practice of chewing miswaak (‘a teeth cleaning twig made from the Salvadora persica[10] tree’[11]). Apparently this natural alternative to the toothbrush has been in use for thousands of years, and features prominently in Muslim hygienical jurisprudence[12], and has many benefits compared to synthetic toothbrushes[13,14,15]. Although this plant-people relationship might not lead you to live longer, you should at least reach the end of your days with a full set of teeth – which must be something to smile about (and to smile with)!

*This intriguing article – which also discusses elephants and beavers, herbivores that use their teeth to eat trees to survive in nature – was brought to my attention by Dr Peter Barlow (School of Biological Sciences, University of Bristol, UK). Cheers, Peter!

**Also known commonly as ‘plaque’[16,17].

[Ed. – if you’re now itching to try out miswa(a)k for yourselves, there’s a rather charming ‘how to do it’ video[18].]

Image: Wikimedia Commons

[1] www.sciencedaily.com/releases/2016/04/160414170015.htm

[2] Environ Health Perspect; DOI:10.1289/ehp.1510363

[3] https://www.mcgill.ca/dentistry/research/our-researchers/touyz

[4] https://louistouyzadventures.wordpress.com/about/

[5] (‘Trees, Tusks, and Roots Relating to Human Health and Teeth’, Jacobs Journal of Physiology. 2015, 1(2): 008

[6] Vincent Zijnge et al. (2010) PLoS ONE 5(2): e9321; doi:10.1371/journal.pone.0009321

[7] http://www.dentalcare.com/en-US/dental-education/continuing-education/ce410/ce410.aspx?ModuleName=coursecontent&PartID=2&SectionID=1

[8] http://www.webmd.boots.com/oral-health/guide/tooth-enamel-erosion-restoration

[9] http://www.nhs.uk/Conditions/Gum-disease/Pages/Symptoms.aspx

[10] http://www.kew.org/science-conservation/plants-fungi/salvadora-persica-toothbrush-tree#

[11] https://en.wikipedia.org/wiki/Miswak

[12] https://en.wikipedia.org/wiki/Muslim_hygienical_jurisprudence

[13] Parveen Dahiya et al., J Ayurveda Integr Med. 3(4): 184–187, 2012; doi: 10.4103/0975-9476.104431

[14] Akhilanand Chaurasia et al., J. Oral Biol. Craniofac. Res. 3(2): 98–101, 2013; doi: 10.1016/j.jobcr.2012.09.004

[15] Fayez Niazi et al., Eur. J. Dent. 10: 301-308, 2016; DOI: 10.4103/1305-7456.1782971

[16] https://microbewiki.kenyon.edu/index.php/Dental_Plaque_Biofilms

[17] Rita Chandki et al., J. Indian Soc. Periodontol. 15(2): 111–114, 2011; doi: 10.4103/0972-124X.84377

[18] https://www.youtube.com/watch?v=eamh-GNUsnI

Nigel Chaffey

E-mail: ku.ca.apshtab@yeffahc.n

Chaffey N. 2016. Plant Cuttings, August, Annals of Botany 118(2): iv–vii.


Articles from Annals of Botany are provided here courtesy of Oxford University Press