Surface-enhanced Raman spectroscopy of genomic DNA from in vitro grown tomato (Lycopersicon esculentum Mill.) cultivars before and after plant cryopreservation

• Structural characteristics of genomic DNAs from tomato cultivars were analyzed.
• Structural changes induced in genomic DNAs upon cryopreservation were discussed.
• Cultivar dependent influence of cryogenic storage on DNA structure has been observed.

In this work the surface-enhanced Raman scattering (SERS) spectra of five genomic DNAs from non-cryopreserved control tomato plants (Lycopersicon esculentum Mill. cultivars Siriana, Darsirius, Kristin, Pontica and Capriciu) respectively, have been analyzed in the wavenumber range 400–1800 cm−1. Structural changes induced in genomic DNAs upon cryopreservation were discussed in detail for four of the above mentioned tomato cultivars. The surface-enhanced Raman vibrational modes for each of these cases, spectroscopic band assignments and structural interpretations of genomic DNAs are reported. We have found, that DNA isolated from Siriana cultivar leaf tissues suffers the weakest structural changes upon cryogenic storage of tomato shoot apices. On the contrary, genomic DNA extracted from Pontica cultivar is the most responsive system to cryopreservation process. Particularly, both C2′-endo-anti and C3’-endo-anti conformations have been detected. As a general observation, the wavenumber range 1511–1652 cm−1, being due to dA, dG and dT residues seems to be influenced by cryopreservation process. These changes could reflect unstacking of DNA bases. However, not significant structural changes of genomic DNAs from Siriana, Darsirius and Kristin have been found upon cryopreservation process of tomato cultivars. Based on this work, specific plant DNA–ligand interactions or accurate local structure of DNA in the proximity of a metallic surface, might be further investigated using surface-enhanced Raman spectroscopy.

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