Predominant paternal inheritance pattern of light-energy processing adaptive traits in red and black spruce hybrids

摘要

Ecophysiological traits related to light energy processing and freezing tolerance are important adaptive traits in plants. Our goal was to investigate the pattern of inheritance of these traits in hybrids using controlled intra- and inter-specific crosses of red spruce (Picea rubens) (RS) and black spruce (Picea mariana) (BS). Our initial working hypothesis was that expected hybrid index categories could be a predictor of adaptive traits. AT least three different sets of parent trees were selected from controlled crosses performed over 3 years, and these trees were located on or near the Acadia Research Forest in New Brunswick, Canada. Species results of dark-adapted photochemical efficiency (Fv/Fm) and light-adapted light energy processing traits, quantum yield (YLD), thermal dissipation efficiency (qN), and chlorophyll fluorescence (Fpc), were consistent with previously published open-pollinated, species provenance results. Initially, YLD, qN, and Fpc, showed an additive inheritance pattern, evident by average hybrid index 50 having a mid-parent value. Because of various crosstypes of the hybrid families, parental analysis, testing male, female, and interaction effects, and having three categories (pure RS, pure BS, and hybrid spruce), revealed significant male and nonsignificant female and interactive effects. Underlying the averaged additive results was a significant species-specific paternal inheritance pattern. Crosses with BS males had 13.7% higher YLD (P=0.001), 15.4% lower qN (P=0.008), and 43.0% higher Fpc (P=0.096) than crosses with either RS or hybrid males. Fv/Fm showed a nonadditive or parental species pattern. Parental analysis of Fv/Fm showed significant male, female, and male x female interaction effects, and further analysis supports a largely species-specific and paternally inherited trait. Freezing tolerance revealed a mixed model of inheritance dominated by species effects. Total dry mass was positively correlated with YLD, and negatively correlated with Fv/Fm and qN, suggesting a biological tradeoff. We know of no other studies in trees demonstrating paternal inheritance of ecophysiological processes that affect adaptation and fitness..