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Apocynum cannabinum: anthocyanin expression in sun and shade

Erica Ross, Ryan Edelen, Matthew Howes and Dana Dudle
Science Research Fellows and Biology Department, DePauw University
Summer 2006

Anthocyanins are water-soluble pigments found in the vacuole of plant cells and are responsible for red, blue, and purple coloring in plants.  They provide protection against damage caused by photooxidation and photoinhibition. Light intensity and other environmental stressors increase the production of anthocyanins.  Apocynum cannabinum produces anthocyanins in its stems.  A large population of Apocynum cannabinum in the DePauw Nature Park produces a wide range of anthocyanin content from green to dark red.  We studied the cause of this variability within and among different populations.

We hypothesized that light intensity and genetic differences between families and populations would affect anthocyanin production.

We collected plants from three populations:  the Quarry Bottom in the DePauw Nature Park, a field in Buffalo Grove, Illinois, and a population from the side of Indiana State Highway 75.  We collected seeds from 34 plants.  We placed the seeds on moist filter paper in a 35ºC growth chamber.  After 10 days, the germinated seeds were transplanted into soil and maintained in the greenhouse.  We transplanted 508 plants from 15 families to the experimental garden outside of the Manning Environmental Field Station.  We built nine boxes with shade cloth that created about 60 percent shade.  There were 250 plants in the shade and 258 plants in the sun.  We used a spectrophotometer and a fiber optic probe to collect data on pigment production on the fifth internode of each plant.  We measured pigment production on 8 dates over 7 weeks. 

Results and Discussion
There was a significant difference in the anthocyanin production between the two treatments; sun plants produced more anthocyanin than shade plants.  Production of anthocyanins increased over time in both the sun and shade plants.  Families of shade plants showed significant variation in anthocyanin production, but families of sun plants did not vary.