Growth is a complex trait determined by the interplay between many genes, of which some play a role at a specific moment during development whereas others play a more general role. To identify the genetic basis of growth in control and drought conditions, natural variation in Arabidopsis rosette growth was followed in 324 accessions by a combination of top-view imaging, high throughput image analysis, modelling of growth dynamics, and end-point fresh weight determination. Genome Wide Association (GWA) mapping of the temporal growth data of control and drought treated plants resulted in the detection of time-dependent quantitative trait loci (QTLs). Mapping of model parameters resulted in another set of QTLs related to the whole growth curve under control and drought conditions. The positive correlation between projected leaf area (PLA) at different time-points during the course of the experiment suggested the existence of general growth factors with a function in multiple developmental stages or with prolonged downstream effects. Many QTLs would not have be identified when growth was evaluated at a single time-point only. Analysis of earlier determined gene expression changes upon drought enabled us to identify for each drought-QTL the most likely candidates.

This is a joint work with Joost JB Keurentjes, Christine Granier and Dick Vreugdenhil