Different response to the UV-stress among Populus alba L. Clones

To evaluate a possible differential behaviour of 5 white poplar genotypes towards UVB radiation, we studied the association between polymorphism data (SNPs) and expression level on genes (such as chs, comt, and rbcL) putatively related to UVB response. Molecular data were integrated with ecophysiological observation. From the ecophysiological data obtained we observed, in stressed plants, a decrease of the maximum efficiency of the PSII, in particular for 3 clones increasing the hours of UVB treatment. Furthermore an abrupt decrease of the values is already present from the second day of stress. The analysis using qRT PCR for the genes studied, for the leaf tissue of the 5 clones treated for 3, 6 and 12 hours with UVB, showed a different pattern of expression, with a dissimilar response among the clones analyzed towards the stress. Both the ecophysiological and the expression data showed a different response particularly for 3 clones that resulted more sensitive to the treatment than the others. The analysis of the polymorphism of the sequences has instead not allowed the construction of associations with the ecophysiological and expression data for absence of missense mutations.