Genome wide analysis of auxin-cytokinin cross-talk

Abstract

Plant hormones have a major role in regulating virtually all aspects of plant physiology. Alterations in hormone distributions and responses have also been responsible for several important agricultural advances, such as the breeding of semi dwarf varieties and increased grain production. In recent years it has become apparent that, in comparison to animal hormones, plant hormones rarely act alone, but rather their signalling pathways are interlocked in complex networks. A prime example is in the interactions between auxin and cytokinins, which are classes of plant hormones that play a particularly important role in regulating plant development. Both hormones act as signals for cell division, cell elongation and cell differentiation in various developmental contexts and often regulate the same developmental process in an antagonistic manner. Despite the obvious importance of the interactions between hormonal pathways, relatively little progress has been achieved in identifying the mechanisms or molecular components that mediate their cross-talk. We feel that with recent advances of our knowledge on the molecular mechanisms of plant hormone action and with genome-wide tools in Arabidopsis, it is now possible to address this issue successfully. In this proposal we plan to elucidate the molecular mechanisms underlying auxin and cytokinin interaction in different developmental contexts.
We bring together European world-class research expertise in auxin and/or cytokinin research focused on three developmental contexts:

• (1) shoot branching,
• (2) root branching
• (3) vascular morphogenesis.

From our work so far on different developmental process we have generated number of tools and materials, which will be shared and systematically tested in all studied processes; our groups have highly complementary specialist expertise in the core genomic and post-genomic technologies needed for the project:

• (1) cell sorting-coupled microarrays,
• (2) bioinformatics,
• (3) cell biology, which will be shared and further developed to achieve our objectives.

As the complexity of our studied problem is far too high to allow intuitive interpretations, we plan to generate a mathematical model(s), which will serve as platform to describe the interactions of other signalling pathways. From the analysis of auxin and cytokinin interactions at the molecular level in three parallel systems we aspire to build a conceptual framework and genomic resources for further analyses of the role of the hormonal control of plant development and productivity. As the crosstalk between auxin and cytokinin is a central determinant of plant development and architecture, these aims are of direct relevance to multiple research themes of the current call related plant productivity. Furthermore, especially through our cell biological approach we will develop new tools for genome wide analysis in plants cultivars. This will allow us to determine the efficiencies of identification and extraction of useful alleles in barley breeding programs based upon wide crosses. Our third major project objective is to use the huge DNA and marker data set obtained in the project to determine important population genetic parameters for barley.