Drought stress tolerance of red and white clover–comparative analysis of some chaperonins and dehydrins

The ecophysiological function linked to the contribution of the legume to the nitrogen supply of the sward, as well as its high content in pastures, make red (Trifolim pratense) and white clover (Trifolium repens) forage plants of economic importance in temperate regions. The study aimed to characterize the expression profiles of some important stress tolerance related proteins in red clover (cv. “Start”), and two white clover cultivars – cv. “Haifa” (medium-leafed) and cv. “Debut” (small-leafed). An attempt has been made to explain the differences in red and white clover potential to sustain unfavorable environmental conditions regarding the obtained results from protein and gene profiling. Rubisco binding protein (RBP), low molecular weight heat shock proteins (HSP), calpains (ClpA and ClpP) and dehydrins (DHN) responded significantly to drought. White clover cv. “Debut” developed the lowest leaf water deficit (WD) compared to the one detected in red clover and the medium leafed white clover cultivar “Haifa”. Immunoblot and RT-PCR showed that the small leafed white clover cv. “Debut” copes with drought stress most efficiently. Detailed gene expression analysis revealed that Y2SK type dehydrins were subjected to alternative splicing under drought and the transcripts were strongly induced in the more drought tolerant small-leafed white clover cultivar “Debut”. A homolog sequence of Y2K dehydrin in T. pratense (GenBank ID: JF748409) and T. repens (GenBank ID: JF748410) have been amplified and an increased transcipt levels of JF748409 were detected in T. pratense drought stressed leaves. The expression pattern of SK2 transcripts showed that this dehydrin type has been down-regulated in both white clover cultivars under water deprivation.

► Expression of stress tolerance related proteins in clover cultivars was assessed.
► The small leafed white clover cultivar coped most efficiently with drought.
► Y2SK dehydrin was up regulated and subjected to alternative splicing under drought.
► Y2K dehydrin homologues in Trifolium pratense and Trifolium repens were amplified.
► SK2 dehydrin was down-regulated under water deprivation.