Effects of temperature and gibberellic acid on phospholipid composition of Avena sativa stem segments

Stem segments taken from Avena sativa plants grown at 10°, 20° or 30° varied in their phospholipid composition depending on the growth temperature; as temperature was lowered, there was a shift towards a greater proportion of unsaturated fatty acids. A significant increase was observed in the concentration of linolenic acid (18:3) as growth temperature was lowered. Although prolonged treatment of oat plants with GA₃ produced marked changes in phospholipid composition of stem segments, these changes did not always accompany the GA₃-induced growth response of segments. Treatment of stem segments with GA₃ for only 20 hr produced a significant growth response with little or no effect on phospholipid composition over this time. The data support the hypothesis that GA₃-induced growth in Avena stem segments can occur without a concomitant change in phospholipid composition.