Lenka Plavcová, Veronika Jandová, Jan Altman, Pierre Liancourt, Kirill Korznikov, Jiří Doležal
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引用次数: 0
Abstract
Background and aims: Understanding anatomical variations across plant phylogenies and environmental gradients is vital for comprehending plant evolution and adaptation. Previous studies on tropical woody plants have paid limited attention to quantitative differences in major xylem tissues, which serve specific roles in mechanical support (fibres), carbohydrate storage and radial conduction (radial parenchyma, rays), wood capacitance (axial parenchyma) and water transport (vessels). To address this gap, we investigate xylem fractions in 173 tropical tree species spanning 134 genera and 53 families along a 2200-m elevational gradient on Mount Cameroon, West Africa.
Methods: We determined how elevation, stem height and wood density affect interspecific differences in vessel, fibre, and specific axial (AP) and radial (RP) parenchyma fractions. We focus on quantifying distinct subcategories of homogeneous or heterogeneous rays and apotracheal, paratracheal and banded axial parenchyma.
Key results: Elevation-related cooling correlated with reduced AP fractions and vessel diameters, while fibre fractions increased. Lower elevations exhibited elevated AP fractions due to abundant paratracheal and wide-banded parenchyma in tall trees from coastal and lowland forests. Vasicentric and aliform AP were predominantly associated with greater tree height and wider vessels, which might help cope with high evaporative demands via elastic wood capacitance. In contrast, montane trees featured a higher fibre proportion, scarce axial parenchyma, smaller vessel diameters and higher vessel densities. The lack of AP in montane trees was often compensated for by extended uniseriate ray sections with upright or squared ray cells or the presence of living fibres.
Conclusions: Elevation gradient influenced specific xylem fractions, with lower elevations showing elevated AP due to abundant paratracheal and wide-banded parenchyma, securing greater vessel-to-parenchyma connectivity and lower embolism risk. Montane trees featured a higher fibre proportion and smaller vessel diameters, which may aid survival under greater environmental seasonality and fire risk.
背景和目的:了解植物系统发育和环境梯度之间的解剖学差异对于理解植物进化和适应至关重要。之前对热带木本植物的研究对主要木质部组织的定量差异关注有限,而木质部组织在机械支撑(纤维)、碳水化合物储存和径向传导(径向实质、射线)、木材电容(轴向实质)和水分运输(血管)方面发挥着特殊作用。为了填补这一空白,我们在西非喀麦隆山海拔2200米的梯度上调查了134属53科173种热带树种的木质部组分:我们确定了海拔、茎高和木材密度如何影响血管、纤维、特定轴向(AP)和径向(RP)实质部分的种间差异。我们重点量化了同质或异质射线以及气管尖、气管旁和带状轴实质的不同亚类:升高相关的冷却与AP分数和血管直径的减少有关,而纤维分数则增加了。由于沿海和低地森林中的高大乔木具有丰富的气管旁和宽带状实质组织,因此海拔较低地区的AP分数会升高。血管中心型和杏仁状 AP 主要与树木高度更高、血管更宽有关,这可能有助于通过弹性木材电容应对高蒸发需求。相比之下,山地树木的特点是纤维比例较高、轴向实质较少、血管直径较小和血管密度较高。山地树木中缺乏AP的现象通常通过延长单列射线切片、直立或方形射线细胞或活体纤维的存在来弥补:海拔梯度影响了木质部的特定部分,海拔较低的树木由于气管旁和宽带实质层丰富而显示出较高的AP,从而确保了血管与实质层之间更大的连通性和较低的栓塞风险。山地树木的纤维比例较高,血管直径较小,这可能有助于在更大的环境季节性和火灾风险下存活。
期刊介绍:
Annals of Botany is an international plant science journal publishing novel and rigorous research in all areas of plant science. It is published monthly in both electronic and printed forms with at least two extra issues each year that focus on a particular theme in plant biology. The Journal is managed by the Annals of Botany Company, a not-for-profit educational charity established to promote plant science worldwide.
The Journal publishes original research papers, invited and submitted review articles, ''Research in Context'' expanding on original work, ''Botanical Briefings'' as short overviews of important topics, and ''Viewpoints'' giving opinions. All papers in each issue are summarized briefly in Content Snapshots , there are topical news items in the Plant Cuttings section and Book Reviews . A rigorous review process ensures that readers are exposed to genuine and novel advances across a wide spectrum of botanical knowledge. All papers aim to advance knowledge and make a difference to our understanding of plant science.