Differences in cellular structure regulate stem elongation of alpine and prairie ecotypes ofStellaria longipesgrown under two contrasting temperature regimes

Abstract

The objectives of this study were to explore differences in the structural features of stem elongation in alpine and prairie ecotypes of Stellaria longipes Goldie in response to two contrasting temperature regimes. The two ecotypes were grown under warmer, 28 °C (day) – 22 °C (night), and cooler, 10 °C (day) – 4 °C (night) temperatures, and under the same light irradiance (∼120 µmol·m–2·s–1) and photoperiod (16 h). Temperature exerts a significant effect on the stem elongation of alpine and prairie ecotypes of S. longipes. Significant retardation of growth occurred in plants grown in cooler temperatures (10 °C (day) – 4 °C (night)), while growth was profoundly enhanced when plants were grown under warmer conditions (28 °C (day) – 22 °C (night)). The ecotypes exhibited differential responses to temperature (owing to differences in their cellular structure), particularly in cell length, the timing of cell wall thickening, the deposition of phenolic compounds, and the changes in cortical microtubule orientation.