Every dog has its day

One of the great hopes of the 1980s (and as far back as the 1940s) was that one plant species would be typical of all plants and could be used as a model for the entirety of plant biology. The plant chosen for that singular honour was thale cress – Arabidopsis thaliana (e.g. Maarten Koornneef and David Meinke). In today’s more enlightened times, we now recognise that this tiny, weedy, short-lived member of the cabbage family is not the one-stop answer to all things rooted and photosynthetic. Accordingly, many plant species have been sought and exploited as models for different aspects of plant biology.

De Aardappeleters / The Potato Eaters.
De Aardappeleters / The Potato Eaters. Vincent Van Gogh / Wikipedia

Now, proudly added to that growing list are Solanum morelliforme and S. clarum. Why? Shelley Jansky et al. propose these two taxa as model species for study of the phenomenon of epiphytism.

An epiphyte is a plant that “grows harmlessly upon another plant (such as a tree)”. Epiphytes are therefore not rooted in the soil, from which medium more typical land plants extract water and nutrients using their roots. Although epiphytism might seem out of the ordinary, it’s a way of life that’s been adopted by almost 10% of vascular plants. This aerial existence – that is far removed from the norm and our familiar concepts of plants and how they interact with their surrounding such as the soil – challenges our views of plant biology gained from ‘model’ species like that non-epiphyte Arabidopsis. Understanding how such plants get their essential inputs – such as water and nutrients – is an intellectually-interesting question. But, it’s also a pressing issue as we contemplate a future where both water and nutrient availability – and humans’ and crops’ more efficient use of both – are major concerns. Study of epiphytism therefore requires an appropriate model organism.

However, recognising that the epiphyte lifestyle involves many differences from typical land plants, Jansky et al. nominate use of these two Solanum spp. specifically for investigating mineral uptake efficiency of epiphytes. And, in support of their suggestion, they cite such favourable properties as the species’ short life cycles (as befits 3-year funding regimes of PhDs..?), their ability to be propagated via tubers or cuttings (to bulk up clonal, replicated material…), and the ease with which they can be grown in controlled environments (to permit proper experimental investigation…).

Recognising also that transgenic manipulations and somatic fusions will allow the movement of genes from these epiphytes to cultivated potato (Solanum tuberosum), may we one day envisage our orchard trees to be decorated with dangling aggregations of potato tubers (like so many bunches of grapes *)? Well, you never know the heights to which research will take you! And that ‘arboriponics’ would release large areas of the soil for growth of other crops…


* But suitably protected to prevent their greening and containing harmful levels of glycoalkaloids, such as solanine

[Ed. – as interesting as that is, the real Solanum news story must surely be the newly-described species Solanum ossicruentum, whose name was “chosen with the help of 150 seventh grade life science students from Pennsylvania, USA”. Although, an even more intriguing newly-named plant taxon is the subgenus Jamesbondia in the Amaranthaceae (the amaranth and goosefoot family) described by Ivonne Sánchez-del Pino and Duilio Iamonico. Sadly, there are only four species in that group, not the 007 we’d love to see!]

Reference List

Maarten Koornneef, David Meinke, 2010, 'The development of Arabidopsis as a model plant', The Plant Journal, vol. 61, no. 6, pp. 909-921 http://dx.doi.org/10.1111/j.1365-313x.2009.04086.x

Richard Flavell, 2009, 'Role of Model Plant Species', Methods in Molecular Biology™, pp. 1-18 http://dx.doi.org/10.1007/978-1-59745-427-8_1

Shelley H. Jansky, Jacob Roble, David M. Spooner, 2016, 'Solanum clarum and S. morelliforme as Novel Model Species for Studies of Epiphytism', Frontiers in Plant Science, vol. 7 http://dx.doi.org/10.3389/fpls.2016.00231

U. Lüttge, 1989, 'Vascular Epiphytes:Setting the Scene', Ecological Studies, pp. 1-14 http://dx.doi.org/10.1007/978-3-642-74465-5_1

Gerhard Zotz, 2013, 'The systematic distribution of vascular epiphytes – a critical update', Botanical Journal of the Linnean Society, vol. 171, no. 3, pp. 453-481 http://dx.doi.org/10.1111/boj.12010

Christopher Martine, Jason Cantley, Emma Frawley, Alice Butler, Ingrid Jordon-Thaden, 2016, 'New functionally dioecious bush tomato from northwestern Australia, Solanum ossicruentum, may utilize “trample burr” dispersal', PhytoKeys, vol. 63, pp. 19-29 http://dx.doi.org/10.3897/phytokeys.63.7743

I. Sánchez-del Pino, D. Iamonico, 2014, ' Jamesbondia , a new subgenus of Alternanthera (Gomphrenoideae, Amaranthaceae) from Central America and the Caribbean Islands ', Plant Biosystems – An International Journal Dealing with all Aspects of Plant Biology, vol. 150, no. 2, pp. 190-200 http://dx.doi.org/10.1080/11263504.2014.941034