© 2007 Heron Publishing—Victoria, Canada
Genetic variation and control of chloroplast pigment concentrations in Picea rubens, Picea mariana and their hybrids. I. Ambient and elevated [CO2] environments
John E. Major (1, 2), Debby C. Barsi (1), Alex Mosseler (1) and Moira Campbell (1)
1. Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre, PO Box 4000, Fredericton, NB E3B 5P7, Canada / 2. Corresponding author (jmajor@nrcan.gc.ca) / Received January 9, 2006; accepted May 12, 2006; published online December 1, 2006
Summary
Traits related to light-energy processing have significant ecological implications for plant fitness. We studied the effects
of elevated atmospheric CO2 concentration ([CO2]) on chloroplast pigment traits of a red spruce (RS) (Picea rubens Sarg.)–black spruce (BS) (P. mariana (Mill.) B.S.P.) genetic complex in two experiments: (1) a comparative species’ provenance experiment from across the near-northern
part of the RS range; and (2) an intra- and interspecific controlled-cross experiment. Results from the provenance experiment
showed that total chlorophyll (a + b) concentration was, on average, 15% higher in ambient [CO2] than in elevated [CO2] (P < 0.001). In ambient [CO2], BS populations averaged 11% higher total chlorophyll and carotenoid concentrations than RS populations (P < 0.001). There were significant species, CO2, and species × CO2 interaction effects, with chlorophyll concentration decreasing about 7 and 26% for BS and RS, respectively, in response to
elevated [CO2]. Results from the controlled-cross experiment showed that families with a hybrid index of 25 (25% RS) had the highest total
chlorophyll concentrations, and families with hybrid indices of 75 and 100 had among the lowest amounts. Initial analysis
of the controlled-cross experiment supported a more additive model of inheritance; however, parental analysis showed a significant
and predominant male effect for chlorophyll concentration. In ambient and elevated [CO2] environments, crosses with BS males had 10.6 and 17.6% higher total chlorophyll concentrations than crosses with hybrid
and RS males, respectively. Our results show that chlorophyll concentration is under strong genetic control, and that these
traits are positively correlated with productivity within and across species. A significant positive correlation between chlorophyll
concentration and the ratio of total plant N to root dry mass was also found (r = 0.872). The almost fourfold decrease in chlorophyll concentration in RS suggests that it would be at a competitive disadvantage
compared with BS in a high [CO2] environment.
Keywords:
adaptive traits, black spruce, carotenoids, chlorophyll, climate change, fitness, hybridization, nitrogen concentration, paternal
inheritance, red spruce.
