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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.