Chlorophyllous catwalk… (Or, Hemerocallis, the ‘lily’ whose day has come?)

What have Arabidopsis thaliana, Lotus japonicus, Zea mays, Lemna gibba and Hemerocallis got in common? They’re all model plants.
Image: José Goulão/Wikimedia Commons.
Image: José Goulão/Wikimedia Commons.

Question: what have Arabidopsis thaliana, Lotus japonicus, Zea mays, Lemna gibba and Hemerocallis got in common? Answer: they’re all model plantsnon-human species that are extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms.

OK, maybe not yet in the case of Hemerocallis, but a very strong – and overwhelmingly compelling? – case for its elevation to that exalted status has been made by María Rodríguez-Enríquez and Robert Grant-Downton. Maybe somewhat presciently, Hemerocallis (the daylily) is apparently often called ‘the perfect perennial’. And there are many good reasons why H. should be accorded model organism status. The two particularly highlighted by the paper’s authors are the strict developmental control of flower opening and flower senescence (programmed cell death, PCD), and its self-incompatibility (SI) system (SI is a general name for several genetic mechanisms in angiosperms that prevent self-fertilization and thus encourage outcrossing). In the words of its most fervent supporters, ‘New insights into fascinating subjects such as PCD, SI systems and the cellular, molecular and genetic basis of morphological innovations could be generated by exploration in this genus.

Equally, more applied studies, such as identifying and studying molecules of potential biomedical importance, would be assisted by embracing Hemerocallis as a model organism. Its impact as a future model will be enhanced by its amenability to cultivation in laboratory and field conditions… In addition, established methods for various tissue and cell culture systems as well as transformation will permit maximum exploitation of this genus by science… We look forward to a future where many more plant biologists are not only aware of, but also actively utilizing, Hemerocallis in research’.

Having reviewed the ‘manifesto’, as far as I can see the only thing against Hemerocallis’ formal adoption as a model plant (is there a committee that rules on such weighty matters? Should there be…?) – apart from the fact that the genus is in the really-hard-to-spell family Xanthorrhoeaceae (well, probably, for now – it seems that its family status is a little labile at present…) – is that it’s not arabidopsis. But neither is Lotus japonicus, nor Zea mays, nor Lemna gibba… And – but not that looks should count for anything – it will certainly look prettier in the lab than arabidopsis (and it is ‘full-size’, not scale-model size)! So, and anyway, Hemerocallis gets my vote!

[If there are deemed to be too many model plants, perhaps organisms should be in place for a 5-year term, and then have to be put up for re-election. How that might change the grant-awarding landscape! – Ed.]