The increasingly fluid Silk Road View largeDownload slide View largeDownload slide What would you imagine was carried along the Silk Road(s), that ancient route that connected the far-East to the near-East and Europe? Silks? Well, yes, and spices, etc.[2,3,4] (and not forgetting traffic in infectious human diseases). But those are tangible, tradable, items, ‘things’. What is being better appreciated nowadays is that it was also ideas that travelled along that circuitous conduit that linked West and East in times long gone by[6,7]. And one of the most important concepts that has recently been unearthed – quite literally! – is irrigation (‘the artificial application of water to land for the purpose of agricultural production’) practices. As all our readers should be aware, plants need water to grow, and simply to survive. In many terrestrial habitats – e.g. deserts – water is in short supply. To enable thirsty crops to survive and prosper to produce grain, etc. for hungry people, human ingenuity hit upon the idea of irrigating those parched soils by bringing in water from places where it is in abundance to those where it isn’t, and is sorely needed. Using drones and satellite imaging techniques, Yuqi Li et al. have uncovered a remarkably well-preserved example of a small-scale irrigation system dating from the 3rd or 4th century AD/CE in the otherwise barren foothills of China’s Tian Shan Mountains (part of a chain of mountain ranges serving as a central corridor for the Silk Road). The importance of this find is that the technology would have allowed the farmers to grow grain crops in a climate that historically receives less than 3 inches (66 mm) of rainfall per year, which is about one-fifth of what is considered necessary to cultivate even the most drought-tolerant strains of millet. Significantly, the irrigation system here in China’s Xinjiang region is similar to those found in other Silk Road sites at the Geokysur river delta oasis in southeast Turkmenistan, and further west at the Tepe Gaz Tavila settlement in Iran, and is nearly identical to that of the Wadi Faynan farming community in southern Jordan[16,17]. Although it is possible that such geographically-dispersed and remote groups could have reached near identical irrigation solutions independently, Li argues that knowledge of early irrigation technologies followed the Silk Route, being passed from one pastoral group to another over thousands of years. This work adds to that of Robert Spengler III et al. that underlines the importance of agriculture and exchange to social developments of the communities in Central Asia during the Iron Age, in the first millennium BC/BCE. Just as the internet is today, so, in days long gone by, it seems that the Silk Road was a sort of information superhighway too. ‘That which connects us truly binds us, each unto another, and both strengthens and emphasises our shared humanity’… [Anonymous]. [Ed. – But, lest we think of all roads as being ‘good’, we are reminded by those who examine the impact(s) of modern-day roads and highways that they aren’t necessarily so beneficial. There are in fact two quite distinct sides to most roads. For example, and on the plus side, roads can promote economic and social development, however, and on the downside, they can hasten deforestation and the rapid disappearance of wild areas and their related biodiversity. To learn more of the current concerns and debate about such developments, interested readers are directed at the papers by Mohammed Alamgir et al., William Laurance and Irene Arrea, Mohammed Alamgir et al., Alex Lechner et al., and Alexander Pfaff et al..] Image from: Wikimedia Commons References  https://festival.si.edu/2002/the-silk-road/smithsonian  https://en.unesco.org/silkroad/about-silk-road  http://factsanddetails.com/china/cat2/sub90/item50.html  http://www.silkroadencyclopedia.com/Orient/ItemsProductsTrade.htm  http://www.cam.ac.uk/research/news/ancient-faeces-provides-earliest-evidence-of-infectious-disease-being-carried-on-silk-road  https://en.unesco.org/silkroad/content/great-silk-roads  http://factsanddetails.com/china/cat2/sub90/item50.html#chapter-14  http://agriculture.vic.gov.au/agriculture/farm-management/soil-and-water/irrigation/about-irrigation  https://pubs.usgs.gov/gip/deserts/what/  Archaeological Research in Asia 12 : 23 – 32 , 2017 ; http://dx.doi.org/10.1016/j.ara.2017.09.005 CrossRef Search ADS  https://www.travelchinaguide.com/attraction/xinjiang/urumqi/tianshan-mountains.htm  https://phys.org/news/2018-01-ancient-irrigation-technology-silk-road.html#jCp  http://www.bbc.co.uk/news/world-asia-pacific-16860974  https://source.wustl.edu/2018/01/irrigation/  http://www.adias-uae.com/dates/dates.htm  http://ftp.jordantimes.com/news/local/scholar-points-out-wadi-faynan%E2%80%99s-economic-archaeological-potential  http://archaeologydataservice.ac.uk/archives/view/cbarl_2015/contents.cfm?mono=164  Journal of Anthropological Archaeology 48 : 295 – 308 , 2017 ; https://doi.org/10.1016/j.jaa.2017.09.002 CrossRef Search ADS  Current Biology 27 : R1130 – R1140 , 2017 ; doi: https://doi.org/10.1016/j.cub.2017.08.067 CrossRef Search ADS PubMed  Science 358 : 442 – 444 , 2017 ; doi: 10.1126/science.aao0312 CrossRef Search ADS PubMed  Jurutera: The Journal of Malaysian Engineers February 2018 : 13 – 16 ; http://www.myiem.org.my/download/downloadlink.aspx?fn= 14086_JURUTERA%20February%202018.pdf&id=14086  Nature Ecology & Evolution 2 : 408 – 409 , 2018 ; doi: 10.1038/s41559-017-0452-8 CrossRef Search ADS PubMed  Economics: The Open-Access, Open-Assessment E-Journal 12 (2018-11) : 1 – 25 ; http://dx.doi.org/10.5018/economics-ejournal.ja.2018-11 ).] Outer space comes to Cambridge View largeDownload slide View largeDownload slide We rightly celebrate the ability of plants to manufacture a wide range of organic compounds – many of whose function(s) we don’t yet understand (and to cover our ignorance we call them secondary metabolites or secondary plant compounds – SPCs[1,2]). But, plants are also adept at creating interesting inorganic compounds too. Arguably, nowhere has this recently been better demonstrated than by Raymond Wightman et al. working with saxifrages (plants of the genus Saxifraga). Scrutinising the white crust that develops on the leaves of Saxifraga scardica they found it to be composed of vaterite – a form of calcium carbonate[5,6]. More often associated with outer space – vaterite has been detected in planetary objects in the Solar System and meteorites – it does occur on Earth, but is rare and previously only known from geological and zoological sources. Its presence in plants is therefore novel. While this discovery poses questions of the mineral’s role in the biology of the plant (which are discussed in the Flora paper), its apparent abundance is also of biomedical interest because vaterite nanoparticles have potential for targeted delivery of anti-cancer drugs[7,8,9]. Since attempts to manufacture vaterite synthetically have proved difficult, this ready-made botanical source provides another example of the health-promoting power of plants. And where was this biomedical breakthrough made?* Not in some far-flung alpine habitat (as might be expected for Saxifraga spp.), but in the botanic garden of Cambridge University in the UK, using specimens from their National Collection of European Saxifrages. Proving – once again (if any further proof were needed…) – that amazing plant discoveries are all around us. *In the interests of balance, it should be pointed out that vaterite has another, albeit less glamorous, use in improving the quality of papers for inkjet printing by reducing the lateral spread of ink[13,14]. Image from: Wikimedia Commons References  http://www.biologyreference.com/Re-Se/Secondary-Metabolites-in-Plants.html  http://www2.nau.edu/~gaud/bio300w/secpd.htm  Flora 241 : 27 – 34 , 2018 ; doi: https://doi.org/10.1016/j.flora.2018.02.006 CrossRef Search ADS  http://www.botanic.cam.ac.uk/Botanic/Plant.aspx?p=27&ix=11&pid=0&prcid=0&ppid=0  http://webmineral.com/data/Vaterite.shtml#.WsTkO38h0dU  https://www.mindat.org/min-4161.html  http://www.cam.ac.uk/research/news/rare-mineral-discovered-in-plants-for-first-time  Daria Trushina et al. , Materials Science and Engineering: C 45 : 644 – 658 , 2014 ; https://doi.org/10.1016/j.msec.2014.04.050 CrossRef Search ADS  S P Dunuweera and R M G Rajapakse 2018 Biomed. Phys. Eng . Express 4 015017; doi: https://doi.org/10.1088/2057-1976/aa9719  https://www.encyclopedia.com/plants-and-animals/plants/plants/saxifrage  http://www.botanic.cam.ac.uk/Botanic/Home.aspx  http://www.botanic.cam.ac.uk/Botanic/TrailPlace.aspx?p=27&ix=522&pid=0&prcid=0&ppid=0  http://www.cam.ac.uk/research/news/rare-mineral-discovered-in-plants-for-first-time  Yohta Mori et al. , Journal of Imaging Science and Technology 54 ( 2): doi: 10.2352/J.ImagingSci.Technol.2010.54.2.020504 Root hairs to halt global warming View largeDownload slide View largeDownload slide Maire Holz et al. provide an intriguing insight into root biology, this time in terms of this organ’s impact upon carbon sequestration within the soil. Studying barley (Hordeum vulgare), they showed that root hairs[3,4,5] increased the rhizosphere (‘the narrow zone of soil surrounding plant roots that is characterised by root exudation and an abundance of micro-organisms which can be beneficial or harmful to plants, or have no effect on root growth and function’[6,7,8]) three-fold, to 1.5 mm. And, total exudation of carbon-rich materials – onto filter paper – was three times greater for wild type plants (which naturally had hairs) than for root-hairless mutants. Consequently, and if these results are found in nature, they not only suggest that root hairs enhance rhizosphere interactions and nutrient cycling in the soil, but also that root hairs may therefore be beneficial to plants under nutrient-limiting conditions. But, one of the biggest potential impacts of these root outgrowths may be that greater carbon allocation below ground – via the organic exudates – may facilitate carbon sequestration[9,10]. Which would have benefits to a world where increases in atmospheric CO2 concentrations are of global concern[11,12,13]. Global warming, finally getting to the root of the solution..? But, just as root hairs have a hitherto unappreciated role in carbon sequestration, another easily overlooked resource in that regard is the dirt in one’s backyard. Well, not ‘dirt’ exactly, as this is rather a dismissive term to apply to the life-sustaining component of the biosphere we consider next – but soil[15,16]. In the intriguingly-titled ‘Current and historical land use influence soil-based ecosystem services in an urban landscape’, Carly Ziter and Monica Turner examine the value of soils in an urban setting from an ecosystem services point of view[18,19]. In particular they emphasise the role that such soils can play in terms of their ability to store carbon – and may even be better than soil in some natural habitats at this. In this way, such ‘green’ spaces not only improve well-being of humans (e.g. [20,21]), but of the whole planet in playing an important part in storing carbon, and keeping some of that out of the atmosphere. Such findings are some comfort when one considers how important are ecosystems such as mangal (what we used to call mangrove swamps in less enlightened times[22,23]). Mangroves in mangal store large amounts of carbon[24,25], and are therefore important sinks in combatting carbon-created climate change. Yet, mangroves are being cut down for various reasons – such as the creation of ‘shrimp’ farms[26,27,28] – and their important ecosystem service in carbon-sequestration is thereby diminished. If one is to influence human behaviour and show such deforesters the error of their ways it is important to provide evidence of the ill effects of those activities. In an attempt to provide such ‘ammunition’, Stuart Hamilton and Daniel Friess have assessed global carbon stocks within mangroves, and potential emissions due to their deforestation, during the period 2000 to 2012[29,30]. But, in the meantime, and until we stop unnecessary destruction of the mangal carbon sink, don’t rush to replace your backyard with a concreted drive for your car(s) – especially given the carbon emissions involved in cement production[31,32]! Image from: Wikimedia Commons References  Annals of Botany 121 : 61 – 69 , 2018 ; doi: 10.1093/aob/mcx127 CrossRef Search ADS PubMed  http://eol.org/pages/1114455/overview  https://www.biology-online.org/dictionary/Root_Hair  Tatiana Bibikova and Simon Gilroy , J Plant Growth Regul 21 : 383 – 415 , 2003 ; doi: 10.1007/s00344-003-0007-x CrossRef Search ADS  Sourav Datta et al. , Plant Soil 346 : 1 – 14 , 2011 ; doi: 10.1007/s11104-011-0845-4 CrossRef Search ADS  http://plantsinaction.science.uq.edu.au/content/421-rhizosphere  David McNear Jr ( 2013 ) Nature Education Knowledge 4 ( 3 ): 1 ; https://www.nature.com/scitable/knowledge/library/the-rhizosphere-roots-soil-and-67500617  Laurent Philippot et al. , Nature Reviews Microbiology 11 : 789 – 799 , 2013 ; doi: 10.1038/nrmicro3109 ) three-fold, to 1.5 mm CrossRef Search ADS PubMed  https://www.greenfacts.org/glossary/abc/carbon-sequestration.htm  https://www.usgs.gov/faqs/what-carbon-sequestration?qt-news_science_products=0#qt-news_science_products  https://www.ucsusa.org/global-warming/science-and-impacts/science/CO2-and-global-warming-faq.html#.WpvIKnzLgdU  https://www.skepticalscience.com/empirical-evidence-for-co2-enhanced-greenhouse-effect.htm  https://climate.nasa.gov/vital-signs/carbon-dioxide/  https://www.soilassociation.org/soil/  http://www.soils.org.uk/1-what-soil  https://www.greenfacts.org/glossary/def/ecosystem-services.htm  Ecological Applications 0(0): 1 – 12 , 2018 ; https://doi.org/10.1002/eap.1689  https://www.nytimes.com/2018/03/06/climate/yard-garden-global-warming.html  Collins Mensah et al. , International Journal of Wellbeing 6 : 142 – 163 , 2016 ; doi: 10.5502/ijw.v6i1.445 CrossRef Search ADS  Yanan Shen et al. , Urban Forestry & Urban Greening 27 : 59 – 68 , 2017 ; https://doi.org/10.1016/j.ufug.2017.06.018 CrossRef Search ADS  http://www.floridaocean.org/uploads/docs/blocks/169/mangals-of-the-world.pdf  https://serc.si.edu/mangrove-ecology-manual-field-course23 : Daniel Alongi , Carbon Management 3 ( 3): 313 – 322 , 2012 ; https://doi.org/10.4155/cmt.12.20 CrossRef Search ADS  Daniel Alongi , Annu. Rev. Mar. Sci . 6 : 195 – 219 , 2014 ; doi: 10.1146/annurev-marine-010213-135020 CrossRef Search ADS  http://mangroveactionproject.org/shrimp-farming/  http://www.csus.edu/envs/documents/theses/fall%202015/vincelli.thesisfinal.fall2015.pdf  Elizabeth Ashton , CAB Reviews Perspectives in Agriculture Veterinary Science Nutrition and Natural Resources 3 ( 003 ); doi: 10.1079/PAVSNNR20083003  Nature Climate Change 8 : 240 – 244 . 2018 ; doi: 10.1038/s41558-018-0090-4 CrossRef Search ADS  https://natureecoevocommunity.nature.com/users/85094-stuart-hamilton/posts/30912-global-carbon-stocks-and-potential-emissions-due-to-mangrove-deforestation-from-2000-to-2012)  http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/  Robbie Andrews , Earth Syst. Sci. Data 10 : 195 – 217 , 2018 ; https://doi.org/10.5194/essd-10-195-2018 ]! CrossRef Search ADS Mouldy concrete is fit for purpose View largeDownload slide View largeDownload slide Human ingenuity is quite a remarkable thing and has allowed us to undertake great projects. But we shouldn’t be so impressed with our own handiwork that we can’t look for help from other lifeforms to improve what we’ve created. Take, for example, concrete. Defined as ‘a blend of aggregates, normally natural sand and gravel or crushed rock …bound together by a hydraulic binder e.g. Portland Cement and activated by water to form a dense semi homogenous mass’, concrete is a construction material at the heart of such impressive buildings as the Pantheon in Rome. But, although concrete is very strong, it is prone to cracking, which can weaken the construction – with potentially lethal consequences if we’re talking about such things as concrete radiation-shielding around a nuclear reactor. Although cracked concrete can be replaced, it will probably only crack again, and again. A better fix would be concrete that could fill in its own cracks – ‘heal’ itself, much as the way bones do when fractured[5,6]. Well, such ‘living-repairing’ concrete is a very real possibility thanks to work by Jing Luo et al.. They prepared concrete in which spores of the fungus Trichoderma reesi[8,9] were embedded. As cracks formed in the concrete, water and oxygen entered the gaps and promoted germination of the spores. As the fungus grew it precipitated calcium carbonate, which eventually filled the newly-created gap, i.e. it effectively ‘healed the cracks’. This crack-closure caused conditions within the concrete to change such that they no longer supported fungal growth. Instead, the fungus formed spores that remain until a new crack forms and calcium carbonate-precipitating filaments can once more develop and seal the cracks. Although this discovery has great potential, one does wonder how much fungal material you’d need to add to make a large concrete structure self-healing and whether all that organic material might actually undermine the strength-giving properties of this otherwise inorganic material. But, that’s a consideration and calculation for the engineers; the biologist in me just thinks this is a rather neat fungus-human ‘mutualism’. And, if that fails to take hold, why not just clad the exterior of the concrete with vaterite-generating saxifrages [see Outer space comes to Cambridge item above]..?* In any event, repairing the concrete has got to be a much more carbon-sensitive solution than replacing it with more carbon-polluting cement [see Root hairs to halt global warming item above…]. *Or, maybe, the outside of the concrete could be sprayed with sea water to mimic the type of concrete used by Roman engineers to construct their famous marine concrete that remarkably continues to strengthen with age[10,11,12]? Image from: Wikimedia Commons References  http://geo.msu.edu/extra/geogmich/portland_cement.html  https://www.hanson.co.uk/en/technical-information/what-is-concrete  https://www.theguardian.com/artanddesign/2016/jan/08/10-best-concrete-buildings-architecture-pantheon-gaudi-corbusier  https://www.sciencedaily.com/releases/2018/01/180117152511.htm  https://www.medicalnewstoday.com/articles/318961.php  https://askabiologist.asu.edu/bone-healing  Construction and Building Materials 164 : 275 – 285 , 2018 ; https://doi.org/10.1016/j.conbuildmat.2017.12.233 CrossRef Search ADS  https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/trichoderma-reesei  https://genome.jgi.doe.gov/Trire2/Trire2.home.html  https://www.theguardian.com/science/2017/jul/04/why-roman-concrete-still-stands-strong-while-modern-version-decays  Marie Jackson et al. , American Mineralogist 102 : 1435 – 1450 , 2017 ; doi: https://doi.org/10.2138/am-2017-5993CCBY CrossRef Search ADS  http://www.bbc.co.uk/news/science-environment-40494248 © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
Annals of Botany – Oxford University Press
Published: Jun 8, 2018
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