© 2006 Heron Publishing—Victoria, Canada
Changes in freezing tolerance, plasma membrane H+-ATPase activity and fatty acid composition in Pinus resinosa needles during cold acclimation and de-acclimation
Françoise Martz (1), Marja-Liisa Sutinen (1, 2, 3), Sari Kiviniemi (1) and Jiwan P. Palta (4)
1. The Finnish Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN-96301 Rovaniemi, Finland / 2. Corresponding author (marja-liisa.sutinen@metla.fi) / 3. The Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie 7, FIN-91500 Muhos, Finland / 4. Department of Horticulture, University of Wisconsin-Madison, WI 53706, USA / Received December 14, 2004; accepted September 30, 2005; published online March 1, 2006
Summary
It has previously been suggested that plasma membrane ATPase (PM H+-ATPase, EC 3.6.1.3.) is a site of incipient freezing injury because activity increases following cold acclimation and there
are published data indicating that activity of PM H+-ATPase is modulated by changes in lipids associated with the enzyme. To test and extend these findings in a tree species,
we analyzed PM H+-ATPase activity and the fatty acid (FA) composition of glycerolipids in purified plasma membranes (PMs) prepared by the two-phase
partition method from current-year needles of adult red pine (Pinus resinosa Ait.) trees. Freezing tolerance of the needles decreased from –56 °C in March to –9 °C in May, and increased from –15 °C
in September to –148 °C in January. Specific activity of vanadate-sensitive PM H+-ATPase increased more than twofold following cold acclimation, despite a concurrent increase in protein concentration. During
de-acclimation, decreases in PM H+-ATPase activity and freezing tolerance were accompanied by decreases in the proportions of oleic (18:1) and linoleic (18:2)
acids and increases in the proportions of palmitic (16:0) and linolenic (18:3) acids in total glycerolipids extracted from
the plasma membrane fraction. This pattern of changes in PM H+-ATPase activity and the 18:1, 18:2 and 18:3 fatty acids was reversed during cold acclimation. In the PM fractions, changes
in FA unsaturation, expressed as the double bond index (1 × 18:1 + 2 × 18:2 + 3 × 18:3), were closely correlated with changes
in H+-ATPase specific activity (r2 = 0.995). Changes in freezing tolerance were well correlated with DBI (r2 = 0.877) and ATPase specific activity (r2 = 0.833) in the PM fraction. Total ATPase activity in microsomal fractions also closely followed changes in freezing tolerance
(r2 = 0.969). We conclude that, as in herbaceous plants, simultaneous seasonal changes in PM H+-ATPase activity and fatty acid composition occur during cold acclimation and de-acclimation in an extremely winter hardy
tree species under natural conditions, lending support to the hypothesis that FA-regulated PM H+-ATPase activity is involved in the cellular response underlying cold acclimation and de-acclimation.
Keywords:
fatty acid unsaturation, frost hardiness, plasma membrane, polar lipids, red pine, seasonal changes.
