Analysis of Sugar Sensing Using Arabidopsis thaliana natural variation

Although it has already been shown that sugars have not only a metabolic function in plants, little is known about the mechanisms by which plants respond to them. High concentrations of sugars arrest the development of young Arabidopsis thaliana seedlings. In order to better understand this process, we exploited the natural variation of two Arabidopsis accessions differing largely in their response to sugars: the laboratory strain Landsberg erecta (Ler), less sensitive, and the more sensitive accession Cape Verde Islands (Cvi). With a set of recombinant inbred lines (RILs) derived from a cross between both accessions, quantitative trait loci (QTLs) for the sugar induced developmental arrest have been identified and then confirmed analysing near isogenic lines (NILs). The QTL GSQ5 co-locates with the QTL for seed dormancy DOG1. There is a positive feedback loop between sugar-ABA signal cascade and Cvi allele of GSQ5/DOG1. Sugar induced the expression of GSQ5/DOG1-Cvi via sugar-ABA signalling cascade, and GSQ5/DOG1-Cvi enhances the sugar-ABA signalling cascade through the induction of ABI4. At the same time, fine mapping of another QTL specific for fructose is currently in progress.