Old meets new
What do you get when you unite the most ancient extant angiosperm with modern, hi-tech molecular biology? Over US$7 million(!). For that is the amount that the American National Science Foundation has awarded to a group of five universities in the USA to sequence the genome of Amborella trichopoda. Amborella trichopoda is a large shrub endemic to the island of New Caledonia in the south Pacific whose main claim to fame lies in its sharing common ancestry with the very first flowering plants (http://en.wikipedia.org/wiki/Amborella). An understanding of its DNA is therefore expected to reveal information that should help us to understand how flowering plants evolved and diversified, and may even provide insight into the key processes that have driven the formation of the world's ecosystems (http://news.ufl.edu/2010/10/14/amborella/). Florida, Pennsylvania State, Buffalo, Arizona and Georgia Universities are involved in the project. According to Pam Soltis – an investigator on the project based at the Florida Museum – ‘The information from the project will allow researchers to determine whether a specific gene or process is unique to a particular plant or goes back to the beginnings of angiosperm evolution. This will enhance efforts to improve agriculture and forestry by giving plant biologists a reference point for understanding all other flowering plant genomes’. Once its genetic secrets have been laid bare, dare one suggest that Amborella might be the new Arabidopsis for the 21st century? Still on the subject of genomes, and for those obsessed with size, Jaume Pellicer and colleagues at the Royal Botanic Gardens (Kew, UK) have found what they believe may be the world's biggest (Botanical Journal of the Linnean Society 164: 10–15, 2010). It is 50 times longer than a human's (and longer than the next biggest genome in the marbled lungfish!), and belongs to Paris japonica.
Image: Scott Zona, Wikimedia Commons.
Photoautotrophs, plumbing new depths
Now that ‘junior’ – AoB PLANTS (http://aobpla.oxfordjournals.org/) – has expanded its broad remit to include phytoplankton, as a responsible older sibling, we at the Annals of Botany ought to make a nod in that direction too. So, here goes. Reef-building corals are a mutually beneficial association between coral polyps (animals similar to a sea anemone) and a photosynthetic dinoflagellate of the genus Symbiodinium (a type of alga whose phytoplanktonic relatives are responsible for such devastating natural phenomena as toxic red tides; http://en.wikipedia.org/wiki/Dinoflagellates). Because of the need of the algal endosymbiont – known as a zooxanthella – for light for photosynthesis it is generally assumed that such corals cannot live successfully at depths much beyond 50 m below sea level (http://en.wikipedia.org/wiki/Coral_reef). So, you can probably imagine the surprise when Daniel Wagner et al. discovered black corals at a depth of 396 m with such dinoflagellate endosymbionts (Proc. R. Soc. B, doi:10.1098/rspb.2010.1681). Although they do not state whether the algae were photosynthetic, they do note that chlorophyll autofluorescence was detected. OK, so black coral is not a reef-builder (and is supposedly asymbiotic, too), but the presence of Symbiodinium raises all sorts of questions about its relationship with its ‘host’, and certainly extends the potential depth for this most famous of symbioses. Which might be useful if anticipated future sea-level rises take all coral communities to deeper depths? One potential downside to this revelation might be increased exploitation pressure on black corals – which are highly prized and valuable as jewellery and so greatly sought after already that they are CITES-listed as endangered (http://en.wikipedia.org/wiki/Black_coral).
Image: Scott France, US National Oceanic & Atmospheric Administration.
New species: from the very small …
‘Seek and thou shalt find’ is a good guiding principle to those who are keen to unearth more and smaller life forms. And this approach has confirmed the identification of a new virus of the genus Marafivirus. In itself not so surprising, but the potential significance of the discovery relates to its being isolated from Panicum virgatum (‘switchgrass’), which is one of mankind's great hopes as a source of biomass energy (and much more besides: http://en.wikipedia.org/wiki/Panicum_virgatum). The new virus identified by Bright Agindotan et al. (Journal of Virological Methods 169:119–128, 2010) is associated with mosaic and yellow streak symptoms on the leaves of switchgrass. Although the full consequences of such ‘infection’ have yet to be understood there are concerns that it could lead to a reduction in host photosynthesis with attendant decreases in biomass. All of which would be a severe blow to attempts to promote switchgrass as an energy crop. And a great ‘weapon’ to be used by those who might not want to see such alternative, greener energy sources developed …?
Image: US National Renewable Energy Laboratory.
…to the very big
OK, one can understand how easy it is to overlook tiny viruses, but when it comes to something as large as a tree you would be forgiven for thinking that they've all been discovered. So what are the chances of finding not only a new species of tree, but a new genus, too? No doubt slim, but actually better than you might expect when the tree is a monotypic genus. Anyway, that's what Carmen Ulloa et al. have achieved (Ann. Missouri Bot. Gard. 97: 457–467, 2010). The tree, Hondurodendron urceolatum, honours both its home – Honduras, to which it appears to be endemic – and its urn-shaped fruit (pictured). For the taxonomically inclined amongst you, it is a eudicot angiosperm in the Aptandraceae within the Santalales; for the size-obsessed amongst you, it can reach up to 12 m. The fieldwork that led to the tree's discovery was funded by Operation Wallacea (http://www.opwall.com/About/index.shtml), named in honour of Alfred Russell Wallace (http://en.wikipedia.org/wiki/Operation_Wallacea), the oft-overlooked, intelligently creative co-inventor of Evolution, along with a certain Mr Charles Darwin. Let us hope that the 100-years' anniversary of Wallace's death – in 2013 – receives as much celebration as was recently accorded to Darwin in his ‘special year’ of 2009.
Image: Jonathan Kolby, http://www.parasiticplants.siu.edu/index.html.
Herbaria prove their worth (150 years on …)
As we anticipate spring – and warmer weather – in the northern hemisphere, a timely item for us all about phenology, ‘the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate’ (http://en.wikipedia.org/wiki/Phenology). A classic botanical example of this phenomenon is the timing of flowering of plants. Trying to understand if flowering is affected by climate change is difficult to do within the life span of individual workers as oftentimes much longer periods of data collection are needed than a human life time. One previously untapped source of such information is the herbaria that lie scattered throughout private and public hands in collections world-wide. As proof of the principle, Karen Robbirt and colleagues (Journal of Ecology, doi:10.1111/j.1365-2745.2010.01727.x) examined 77 specimens of the early spider orchid (Ophrys sphegodes) collected between 1848 and 1958 and held at the Royal Botanic Gardens, Kew (UK) and the Natural History Museum (London, UK). Because each specimen contains details of when and where it was picked, the researchers were able to match this with Meteorological Office records to examine how mean spring temperatures affected the orchids' flowering. Comparing those data with field observations of peak flowering of the same orchid species in the Castle Hill National Nature Reserve (East Sussex, UK) between 1975 and 2006, they found that the response of flowering time to temperature was identical both in herbarium specimens and field data. In both the pressed plants and the field observations, the orchid flowered 6 days earlier for every 1 oC rise in mean spring temperature. The study opens up a new lease of life for the estimated 2·5 billion dead plant and animal specimens held in natural history collections in museums and herbaria (http://www.alphagalileo.org/ViewItem.aspx?ItemId=85439&CultureCode=en). Phenology should not be confused with phrenology (‘ …a pseudoscience primarily focused on measurements of the human skull …’; http://en.wikipedia.org/wiki/Phrenology). Although it is acknowledged that certain ill-informed individuals suggest that adults who spend their time squashing plants and locking them away in drawers should have their heads examined …
Image: The People's cyclopedia of universal knowledge, William Harrison De Puy, 1883.
The oldest game of hide-and-seek?
Every living thing (and many a dead one!) is potentially food for another living organism. So, trying to postpone being the final meal yourself is important, and organisms have developed many ways of remaining uneaten just a little while longer. One of the most botanical of subterfuges concerns insects that pretend to be leaves in the hope that they will avoid detection and live to fly another day. As with many aspects of behaviour the evolutionary origins are often shrouded in mystery, not least because of limited fossil evidence. But work by Yongjie Wanga and colleagues (PNAS 107: 16212–16215, 2010) suggests that insect leaf mimicry is at least 165 million years old. They found evidence of ‘pinnate leaf mimesis’ in two new species of lacewings (Neuroptera) from rocks of Middle Jurassic age, indicating specialisation between insects and gymnosperms. This discovery also demonstrates a pre-angiosperm development of this insect behaviour. The fossil record suggests that this ‘phyllomimetic’ lineage became extinct during the Early Cretaceous. Which implies it was not such a successful mimicry, after all. Unless they're not really extinct, just very well hidden!
Image: Adrian Pingstone, Wikimedia Commons.
Insects duped by plants
Continuing with the insect–plant interactions theme, we have another ancient mystery – that actually turns out to be a sort of tri-kingdom ménage à trois. Intrigued? Read on! Whilst it is not news that plants emit odours that can attract animals to their flowers for important ecosystem services such as cross-pollination, Johannes Stökl and colleagues have demonstrated some of the unexpected subtleties of the olfactory relationship that the Solomon's lily has with its insect visitors (Current Biology 20: 1846–1852, 2010). The team discovered that the odour emitted by Arum palaestinum attracts pollinating drosophilids (so-called vinegar flies, which includes the genus Drosophila) because it mimics the aroma released during alcoholic fermentation of rotting fruit initiated by yeast. The deception is the more unusual because two of the mix of six chemicals are extremely rare in plants, but are typical of wine and vinegar. Neurophysiological measurements, which included examining electroantennograms (I'm not making this up!) recording the responses of the flies' antennae to the flower's bouquet, suggested that the floral scent ‘targets a deeply conserved neuronal pathway specifically tuned to yeast odors’ (http://www.eurekalert.org/pub_releases/2010-10/mpif-dlf100610.php). And by way of adding insult to injury, not only is there no alcoholic beverage for the flies to sup (nor even nectar to imbibe), they suffer the indignity of being trapped in the flower overnight and not released until the next day. OK, maybe no hang-over, but at least they do escape alive (to be fooled again …).
Image: Johannes Stökl, Max Planck Institute for Chemical Ecology.
Monarchs' marvellous milkweed medicine
Completing this trio of insect–plant interactions, we have a quasi-ethnobotanical theme. For millennia humans have used plants and their products as sources of medicines to make us better. But it seems that this exploitative behaviour is not restricted to Mankind. Thierry Lefèvre and co-workers present evidence that Monarch butterflies use milkweed in this way (Ecology Letters 13: 1485–1493, 2010); however, the adult butterflies do not make use of the plant ‘medicine’ for themselves, but use it to ensure that any benefit derived is for their offspring. This conclusion was reached after recognising that female butterflies suffering from protozoan parasite infection lay their eggs on the toxic plants, which consequently reduce infection in the caterpillars that develop. In this way the future generation benefits, not the parental one. The researchers believe this to be the first demonstration of trans-generational medication in nature. Now, if only the Monarchs could find some medicine to help them survive the lethal effects of feeding on genetically engineered Bt-maize (as some individuals still believe to be an issue: http://www.suite101.com/content/monarch-butterfly-migration-a50751; but see also http://en.wikipedia.org/wiki/Transgenic_maize) …
Image: Keneth Dwain Harrelson, Wikimedia Commons.
Happy New Year!
It is now a year since this monthly column was launched on to an unsuspecting world, and – as befits the start of a New Year – it is time to reflect on those past 12 months. In a word, the whole experience has been ‘interesting’, and I look forward to continuing to scour the plant-based news spectrum from ‘botanical oddities’ to major new plant-based research and developments in the year ahead. Apart from the impact the column has had on me, it seems it has also had wider impacts – at least two that I'm aware of. First, this column has been described as the best of its kind on the Agricultural Biodiversity Weblog (http://agro.biodiver.se/2010/06/nibbles-rhoades-trigonella-plant-nutrition-annals-of-botany-roundup-vitamin-a-insect-week-yeast-biocultural-diversity-online/). Modesty prevents me from using that as a ‘tagline’ for the column, but a big ‘tack så mycket’ to my Swedish fans! Second, the column was embroiled in controversy when an item entitled ‘When is a plant food not a plant food?’ (http://aob.oxfordjournals.org/content/105/6/v.full) was considered to perpetuate the myth that mephedrone (a ‘Class B’ banned drug in the UK) was actually a plant food. In practice this is the ‘claim’ made by the compounds’ purveyors so that they can flout the law and continue to sell the stuff in places like the UK. Still, a clarification was issued in the column (http://aob.oxfordjournals.org/content/106/4/iii.full) in response to a reader's request. The main outcome of that incident seems to be that Plant Cuttings now has two citations in the Wikipedia article about mephedrone (http://en.wikipedia.org/wiki/Mephedrone). I'm not sure if this counts as a claim to fame, or not, but it emphasises the ground-breaking, fearless, edgy nature of the journalism in this monthly polemic, and helps to bring the column to the attention of a much wider audience. However, I do not intend to run any more items on mephedrone – it's just far too controversial! But, plant ‘food’ is certainly not on my list of banned topics!Yours in planta (not that Planta!) P. Cuttings (for so my boss advises me is how I'm referred to in certain search engines!)
Image: Wikimedia Commons.