State Key Laboratory of Forest Cultivation, Central South University of Forestry and Technology, Changsha, 410000, People's Republic of China.
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, People's Republic of China.
BMC Plant Biol. 2024 May 17;24(1):414. doi: 10.1186/s12870-024-05103-7.
Variations in hydraulic conductivity may arise from species-specific differences in the anatomical structure and function of the xylem, reflecting a spectrum of plant strategies along a slow-fast resource economy continuum. Spruce (Picea spp.), a widely distributed and highly adaptable tree species, is crucial in preventing soil erosion and enabling climate regulation. However, a comprehensive understanding of the variability in anatomical traits of stems and their underlying drivers in the Picea genus is currently lacking especially in a common garden.
We assessed 19 stem economic properties and hydraulic characteristics of 17 Picea species grown in a common garden in Tianshui, Gansu Province, China. Significant interspecific differences in growth and anatomical characteristics were observed among the species. Specifically, xylem hydraulic conductivity (K) and hydraulic diameter exhibited a significant negative correlation with the thickness to span ratio (TSR), cell wall ratio, and tracheid density and a significant positive correlation with fiber length, and size of the radial tracheid. PCA revealed that the first two axes accounted for 64.40% of the variance, with PC1 reflecting the trade-off between hydraulic efficiency and mechanical support and PC2 representing the trade-off between high embolism resistance and strong pit flexibility. Regression analysis and structural equation modelling further confirmed that tracheid size positively influenced K, whereas the traits DWT, D_r, and TSR have influenced K indirectly. All traits failed to show significant phylogenetic associations. Pearson's correlation analysis demonstrated strong correlations between most traits and longitude, with the notable influence of the mean temperature during the driest quarter, annual precipitation, precipitation during the wettest quarter, and aridity index.
Our results showed that xylem anatomical traits demonstrated considerable variability across phylogenies, consistent with the pattern of parallel sympatric radiation evolution and global diversity in spruce. By integrating the anatomical structure of the stem xylem as well as environmental factors of origin and evolutionary relationships, our findings provide novel insights into the ecological adaptations of the Picea genus.
木质部解剖结构和功能的种间差异可能导致水力传导率的变化，反映了植物在慢-快资源经济连续体上的一系列策略。云杉（Picea spp.）是一种分布广泛且适应性很强的树种，对防止土壤侵蚀和调节气候至关重要。然而，目前人们对云杉属茎解剖结构的变异性及其潜在驱动因素缺乏全面的了解，特别是在共同园中。
我们评估了在中国甘肃省天水市共同园中生长的 17 种云杉的 19 种茎经济特性和水力特性。观察到这些物种在生长和解剖特征方面存在显著的种间差异。具体来说，木质部水力传导率（K）和水力直径与厚度与跨度比（TSR）、细胞壁比、管胞密度呈显著负相关，与纤维长度和径向管胞大小呈显著正相关。PCA 表明，前两个轴解释了 64.40%的方差，PC1 反映了水力效率和机械支撑之间的权衡，PC2 代表了高栓塞阻力和强纹孔灵活性之间的权衡。回归分析和结构方程模型进一步证实，管胞大小正向影响 K，而 DWT、D_r 和 TSR 等特征则通过间接方式影响 K。所有特征都没有显示出与系统发育的显著关联。Pearson 相关分析表明，大多数特征与经度之间存在很强的相关性，其中最显著的影响因素是最干旱季度的平均温度、年降水量、最湿润季度的降水量和干旱指数。
我们的研究结果表明，木质部解剖特征在系统发育上具有很大的变异性，这与云杉的平行同域辐射进化和全球多样性模式一致。通过整合茎木质部的解剖结构以及起源和进化关系的环境因素，我们的研究结果为云杉属的生态适应提供了新的见解。
