Significance of exogenous abscisic acid (aba) in low temperature stress for free fatty acid contents in lipid fraction of potato cultivars 'saskia' and 'desiree' in vitro

Virusfree in vitro potato clones Saskia and Desiree were exposed to low temperature stress (4 deg C) and/or to ABA treatment (7.57. 10** (-5)M) with the aim to evaluate changes in free fatty acid contents on the cellular level. The exogenous ABA at 4 deg C diminished the lipid fraction stearic acid contents (4.8% in Saskia and 5.2% in Desiree) with regard to the ABA untreated plants (9.7% in Saskia and 7.4% in Desiree) and rose percentage of free linoleic acid (33.9% in Saskia and 40.6% in Desiree) with regard to the normal growth temperature (20.4% in Saskia and 24.0% in Desiree). At low growth temperature (4 deg C) the exogenous ABA caused in Saskia a drop (9.0%) and in Desiree an increase (22.3%) of free oleic acid in comparison with the control medium, where plants contained 22.3% (Saskia) or 20.1% (Desiree) of oleic acid. On the contrary, exogenous ABA at 4 deg C strongly rose the free linolenic contents in Saskia plants (35.7%) and did not significantly reduce its proportion in Desiree plants (18.8%) with regard to plants from the control medium at low growth temperature (Saskia 18.8% and Desiree 22.7%). With ABA presence during the 10 days growth period at low stress temperatures we observed an increased unsaturated/saturated free fatty acids ratio (Saskia 4.0; Desiree 4.8) with regard to the normal growth temperature (Saskia 2.8; Desiree 3.0). Unsaturated/saturated fatty acids ratio linarly and negatively correlated with manganese content (r = -0.75; r**2 = 56.3%) as well as with water content (r = -0.79; r**2 = 62.6%) of plant samples. The palmitic acid content was linearly dependent on ABA contents in samples under study (r = 0.98; r**2 = 95.6%). Samples linolenic and oleic acid relative contents were strongly, but negatively correlated (r = -0.98; r**2 = 96.8%).