Increasing plant growth and productivity by manipulating vascular development

Climate models and recent changes in weather pattern strongly suggest that we are entering a period in which large parts of the globe experience more frequent exposure to extreme and changeable weather. While the effect of these changes on patterns of plant growth is unclear, technologies that increase productivity and overcome adverse effects of climate change are likely to be increasingly sought after. Consequently, there is a need to understand how plant growth is regulated and to what extent it can be manipulated to increase productivity even in the face of fluctuating or adverse environmental conditions.
In the annual plant Arabidopsis, we have identified that signaling between a peptide ligand, CLE41 and a receptor kinase, PXY controls cambial cell divisions and have demonstrated that manipulating this pathway leads to an increase in both plant growth and seed production (Etchells and Turner, 2010; Etchells et al., 2012; Etchells et al., 2013). More recently we have been able demonstrate that altering the expression of the poplar homologues of CLE41 and PXY increases cambial cell division indicating a central role for this pathway in the evolution of radial growth in trees. Precise tissue-specific expression of these genes resulted in a two-fold increase in growth. No only did altering PXY-CLE increase vascular cell divisions, but also showed very large increases in plant height and leaf size suggesting a more general role for this pathway in regulating plant growth (Etchells et al., 2014). These results demonstrate that engineering PXY/CLE41 signaling offers a means to increase plant productivity in plants as diverse as the annual weed Arabidopsis to poplar trees.

Project aims:
1. Understand how PXY-CLE is able to regulate plant growth.
2. Determine to what extent manipulating PXY-CLE signaling is able to override environmental stimuli that regulate plant growth.
3. Better understand the relationship between vascular development and plant growth
This will be carried out by;
1. Looking at novel CLE signaling molecules are further able to increase plant growth.
2. Examine tobacco plants with altered photosynthetic capacity in order to understand the relationship between photosynthesis, growth and vascular development.
3. Study how other pathways that increase vascular development also affect plant growth.
4. Determine to what extent signals in the vascular tissue are able to override environmental growth cues.

Etchells, J.P., Mishra, L., Kumar, M., Campbell, L., and Turner, S.R. (2014). "Wood Formation in Trees Is Increased by Manipulating Pxy-Regulated Cell Division". submitted.
Etchells, J.P., Provost, C.M., Mishra, L., and Turner, S.R. (2013). "Wox4 and Wox14 Act Downstream of the Pxy Receptor Kinase to Regulate Plant Vascular Proliferation Independently of Any Role in Vascular Organisation". Development 140, 2224-2234.
Etchells, J.P., Provost, C.M., and Turner, S.R. (2012). "Plant Vascular Cell Division Is Maintained by an Interaction between Pxy and Ethylene Signalling". PLoS Genet. 8, e1002997
Etchells, J.P., and Turner, S.R. (2010). "The Pxy-Cle41 Receptor Ligand Pair Defines a Multifunctional Pathway That Controls the Rate and Orientation of Vascular Cell Division". Development 137, 767-774.