Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695, USA.
Tree Physiol. 2011 Jan;31(1):78-91. doi: 10.1093/treephys/tpq107.
Variation in leaf-level gas exchange among widely planted genetically improved loblolly pine (Pinus taeda L.) genotypes could impact stand-level water use, carbon assimilation, biomass production, C allocation, ecosystem sustainability and biogeochemical cycling under changing environmental conditions. We examined uniformity in leaf-level light-saturated photosynthesis (A(sat)), stomatal conductance (g(s)), and intrinsic water-use efficiency (A(sat)/g(s) or δ) among nine loblolly pine genotypes (selected individuals): three clones, three full-sib families and three half-sib families, during the early years of stand development (first 3 years), with each genetic group possessing varying amounts of inherent genetic variation. We also compared light- and CO(2)-response parameters between genotypes and examined the relationship between genotype productivity, gas exchange and photosynthetic capacity. Within full-sib, half-sib and clonal genotypes, the coefficient of variation (CV) for gas exchange showed no consistent pattern; the CV for g(s) and δ was similar within clonal (44.3-46.9 and 35.5-38.6%) and half-sib (41.0-49.3 and 36.8-40.9%) genotypes, while full-sibs showed somewhat higher CVs (46.9-56.0 and 40.1-45.4%). In contrast, the CVs for A(sat) were generally higher within clones. With the exception of δ, differences in gas exchange among genotypes were generally insignificant. Tree volume showed a significant positive correlation with A(sat) and δ, but the relationship varied by season. Individual-tree volume and genotype volume were positively correlated with needle dark respiration (R(d)). Our results suggest that uniformity in leaf-level physiological rates is not consistently related to the amount of genetic variation within a given genotype, and δ, A(sat) and R(d) were the leaf-level physiological parameters that were most consistently related to individual-tree and genotype productivity. An enhanced understanding of molecular and environmental factors that influence physiological variation within and between loblolly pine genotypes may improve assessments of genotype growth potential and sensitivity to global climate change.
不同的基因改良火炬松（Pinus taeda L.）基因型在叶片水平上的气体交换可能会影响林分水平的水分利用、碳同化、生物量生产、C 分配、生态系统可持续性和生物地球化学循环，特别是在环境条件发生变化的情况下。我们研究了在林分早期发育阶段（前 3 年），9 个火炬松基因型（选择的个体）之间叶片水平的光饱和光合作用（A(sat)）、气孔导度（g(s)）和内在水分利用效率（A(sat)/g(s)或 δ）的均匀性，这些基因型包括 3 个无性系、3 个全同胞家系和 3 个半同胞家系，每个遗传群体都具有不同程度的固有遗传变异。我们还比较了基因型之间的光和 CO(2)响应参数，并研究了基因型生产力、气体交换和光合能力之间的关系。在全同胞、半同胞和无性系基因型中，气体交换的变异系数（CV）没有一致的模式；g(s)和 δ 的 CV 在无性系（44.3-46.9 和 35.5-38.6%）和半同胞（41.0-49.3 和 36.8-40.9%）基因型中相似，而全同胞的 CV 则略高（46.9-56.0 和 40.1-45.4%）。相比之下，无性系中 A(sat)的 CV 通常较高。除了 δ 之外，基因型之间的气体交换差异通常不显著。树木体积与 A(sat)和 δ 呈显著正相关，但这种关系因季节而异。单株树体积和基因型体积与针叶暗呼吸（R(d)）呈正相关。我们的结果表明，叶片水平生理速率的均匀性与特定基因型内遗传变异的数量并不一致，而 δ、A(sat)和 R(d)是与单株和基因型生产力最一致相关的叶片生理参数。对影响火炬松基因型内和基因型间生理变异的分子和环境因素的深入了解，可能会提高对基因型生长潜力和对全球气候变化敏感性的评估。
