Outer space comes to Cambridge

Some saxifrages are almost literally out of this world.

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 compoundsSPCs). But, plants are also adept at creating interesting inorganic compounds too.

Saxifraga decipiens
Saxifraga decipiens. Photo: Anneli Salo / Wikipedia

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. 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.

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.

Reference List

Wightman, R., Wallis, S., & Aston, P. (2018). Leaf margin organisation and the existence of vaterite-producing hydathodes in the alpine plant Saxifraga scardica. Flora, 241, 27–34. https://doi.org/10.1016/j.flora.2018.02.006

Trushina, D. B., Bukreeva, T. V., Kovalchuk, M. V., & Antipina, M. N. (2014). CaCO3 vaterite microparticles for biomedical and personal care applications. Materials Science and Engineering: C, 45, 644–658. https://doi.org/10.1016/j.msec.2014.04.050

Dunuweera, S. P., & Rajapakse, R. M. G. (2017). Encapsulation of anticancer drug cisplatin in vaterite polymorph of calcium carbonate nanoparticles for targeted delivery and slow release. Biomedical Physics & Engineering Express, 4(1), 015017. https://doi.org/10.1088/2057-1976/aa9719

Mori, Y., Enomae, T., & Isogai, A. (2010). Application of Vaterite-Type Calcium Carbonate Prepared by Ultrasound for Ink Jet Paper. Journal of Imaging Science and Technology, 54(2), 020504. https://doi.org/10.2352/J.ImagingSci.Technol.2010.54.2.020504

  • […] 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..?* […]