ALOKAM, SUNEETHA*, CHENDANDA C CHINNAPPA, AND DAVID M REID. Department of Botany, University of Calgary, Calgary, AB T2N1N4, Canada. - Red/Far red light-mediated shade avoidance stem elongation response and anthocyanin accumulation in alpine and prairie ecotypes of Stellaria longipes .
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