The ratio of red light (R) to far red (FR), R/FR light varies greatly between different environments. Plants perceive this variation in the quality of light through phytochromes and regulate their growth and development in response to these signals. We compared the shade avoidance stem elongation response and anthocyanin accumulation between alpine (1D) and prairie ecotypes (7B) of Stellaria longipes under varied R/FR ratios of 0.7 and 1.9 while all other environmental conditions were maintained at uniform levels. The prairie ecotype considered to be the shade avoider showed a high degree of stem elongation in response to R/FR 0.7 than under R/FR 1.9 as compared to alpine ecotype. Correlation between the effect of varied R/FR light on anthocyanin levels and Phenyl alanine ammonia lyase (PAL) activities were also studied: 1) The levels of anthocyanin in 7B, as compared to 1D, were significantly higher under high R/FR light and under reduced R/FR both 1D and 7B showed almost the same levels of anthocyanin; 2) Etiolated 7B plants when transferred to both high and reduced R/FR conditions showed highest PAL activity at 48h. There was no significant difference in PAL activity under varied R/FR light; 3) Etiolated 1D plants also showed similar trends with highest activity at 48h, however the overall PAL activity under both reduced and high R/FR light was significantly less as compared to 7B; These results indicate that varied R/FR light causes significant difference in the stem elongation and accumulation of anthocyanin but not in PAL activity.

Key words: Stellaria , anthocyanin, PAL, Red/Far red light