LOOKING FOR MOLECULAR AND PHYSIOLOGICAL MARKERS OF OSMOTIC ADJUSTMENTIN SUNFLOWER

Two families of Helianthus lines, T- (low desiccation rate) and T+ (lo w desiccation rate), with contrasting osmotic adjustment (OA), obtaine d from a divergent selection programme, were compared for several morp hological traits, ecophysiological parameters and molecular markers. T he physiological analysis in a glasshouse experiment showed that the t wo families were identical in irrigated conditions except for a single trait, relative water loss (RWL: water loss rate of excised leaves). RWL could be used for these genotypes as a physiological marker of OA. A molecular analysis of the two contrasting lines, using differential screening of cDNA libraries, led to the isolation of three specific c DNAs, one of which, DRS26, showed high sequence homology with a mammal ian amino-acid transporter. Subsequent RFLP and STS studies, using DRS 26 and RAPD bulked analysis, enabled the identification of putative mo lecular markers of RWL and OA in T-:T+ sunflower.