Hydraulic traits are influenced by phylogenetic history in the drought-resistant, invasive genus Juniperus (Cupressaceae).
Hydraulic traits are influenced by phylogenetic history in the drought-resistant, invasive genus Juniperus (Cupressaceae).
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DOI：
10.3732/ajb.95.3.299
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发表时间：
2008-03
影响因子：
3
通讯作者：
C. Willson;Paul S. Manos;R. B. Jackson
中科院分区：
文献类型：
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作者：
C. Willson;Paul S. Manos;R. B. Jackson
在柏科针叶树属中，许多物种在干旱和半干旱地区的分布、丰富度和优势度都在迅速增加。为了帮助了解刺柏在干旱生境中的成功，我们研究了与其耐水分胁迫有关的水力学性状，包括木质部空化的脆弱性、比电导率(K(S))、管胞直径、导管加强、茎和根的木材密度以及来自美国和加勒比地区的14种植物的比叶面积(SLA)。一种基于DNA序列的新的系统发育图使用传统的跨物种关联和独立的对比关联来测试空化易感性与其他特征之间的关系。所有树种在根和地上部都对水分胁迫诱导的空化表现出中等到高度的抗性。我们发现了之前基于叶缘锯齿(锯齿和光滑)的两个分支的强烈系统发育支持。锯齿枝的树种对茎和根木质部空化的抗性比光滑枝的高34-39%，∼比光滑枝低35%，K值低35%(S)，SLA值低39%。根和茎的抗气蚀和SLA都是高度保守的性状。分支内高度的保守性表明，杜松属物种的水力特征强烈地反映了系统发育历史。观察到的对空化的高度抵抗可能有助于解释为什么刺柏在最近美国西南部的极端干旱中存活下来，并扩展到美国西部和中部的干旱栖息地。
In the conifer genus Juniperus (Cupressaceae), many species are increasing rapidly in distribution, abundance, and dominance in arid and semiarid regions. To help understand the success of junipers in drier habitats, we studied hydraulic traits associated with their water stress resistance, including vulnerability to xylem cavitation, specific conductivity (K(S)), tracheid diameter, conduit reinforcement, and wood density in stems and roots, as well as specific leaf area (SLA) of 14 species from the United States and the Caribbean. A new phylogeny based on DNA sequences tested the relationships between vulnerability to cavitation and other traits using both traditional cross-species correlations and independent contrast correlations. All species were moderately to highly resistant to water-stress-induced cavitation in both roots and shoots. We found strong phylogenetic support for two clades previously based on leaf margin serration (serrate and smooth). Species in the serrate clade were 34-39% more resistant to xylem cavitation in stems and roots than were species in the smooth clade and had ∼35% lower K(S) and 39% lower SLA. Root and stem resistance to cavitation and SLA were all highly conserved traits. A high degree of conservation within clades suggests that hydraulic traits of Juniperus species strongly reflect phylogenetic history. The high resistance to cavitation observed may help explain the survival of junipers during recent extreme droughts in the southwestern United States and their expansion into arid habitats across the western and central United States.