CHANGES IN MESSENGER-RNA POPULATION DURING COLD-ACCLIMATION IN 2 POTATO LINES OF SOLANUM-SOGARANDINUM DIFFERING BY THEIR COLD-HARDINESS

An increase in cold hardiness and changes in translatable mRNA in a fe w wild potato lines of Solanum sogarandinum were analysed during cold acclimation. All lines were fully hardened when exposed for eight days at 4 degrees C day/night temperature regime. The most hardy line 1 de veloped its cold hardiness from -3.2 degrees C (LT(50), killing temper ature) to - 8.9 degrees C and the least hardy line 10 increased its fr eezing tolerance from -2.5 degrees C (LT(50)) to -6.5 degrees C. Poly (A) mRNA from cold hardened and unhardened plantlets of the lines 1 an d 10 was isolated and in vitro translation products were separated by two dimensional-PAGE. Analysis of the profiles of the in vitro transla tion products of the hardened plantlets of the line 1 revealed changes in the abundance of approximately 31 products in the range of molecul ar weights from 14 kDa to 69 and pI values from 6.7 to 5.0. As many as 26 products increased in their amount during cold acclimation and two other proteins decreased. Only three novel translation products with the M(r) of 18 kDa and two of 45 kDa were identified when the plantlet s were subjected to cold treatment. Most of the products which undergo ne changes were found in the group of low molecular weight proteins wi th the molecular masses from 14 kDa to 21 and from 24 kDa to 35. In th e less hardy line 10 only 19 products were found to change during cold acclimation and there were not visible newly induced products. All th e changes in the translation products in the both lines appeared after two days of cold treatment while their frost resistance barely increa sed. The data clearly suggests that the increase in the frost resistan ce during cold acclimation was correlated with the changes in the tran slatable mRNA and that more changes in the mRNA were found during cold hardening in the more hardy line.