Former member of the department, Professor Miltos Tsiantis, arrived in a cold and snowy Oxford last week to give a fascinating talk on his research into morphological diversity. Miltos and his research group at the Max Planck Institute are interested in how the diversity that we observe in plant morphologies is controlled at the genetic level. Specifically, they are attempting to understand how distinct leaf forms arise in Arabidopsis thaliana and its close relative Cardamine hirsuta. Arabidopsis forms simple leaves, in which each leaf is composed of a single leaf blade. In contrast, Cardamine forms compound leaves, which are composed of multiple individual subunits known as leaflets. The wealth of genetic resources available in Arabidopsis, and the relative ease that they can be transferred to Cardamine, makes this an attractive and powerful study system.
The seminar focused on various genes identified by the Tsiantis lab, that control formation of the repeated outgrowths that underpin compound leaf formation. Of particular interest was the discovery of the REDUCED COMPLEXITY (RCO) gene in Cardamine, which they have shown represses growth at the margins of developing leaflets. Interestingly, no RCO ortholog is found in Arabidopsis, but expression of the Cardamine RCO resulted in a switch to more compound-like leaves. Miltos went on to explain how studying the evolutionary history of RCO has revealed that changes in promoter regions and protein stability help facilitate diversification in leaf morphology. It will be interesting to see if these features are equally prominent in other examples of plant morphological diversification.
An interesting discussion followed the seminar, with questions raised about the possible adaptive significance of leaf morphological diversity. This looks set to be an active area of research in the future, and it will be interesting to see what insight RCO provides.
Dr Tom Hughes is postdoctoral researcher in the department, researching the transcriptional regulation that underpins the development of Kranz anatomy.