Leaf Venation Variation and Phenotypic Plasticity in Response to Environmental Heterogeneity in Parrotia subaequalis (H. T. Chang) R. M. Hao et H. T. Wei, An Endemic and Endangered Tree Species from China

Zhiyi Jia,Jing Yang,Yanming Fang,Lifang Zhang,Yang Huang

doi:10.3390/f9050247

Abstract

Plant leaf vein traits are partially the result of adaptation to environmental factors during long-term evolution. For terrestrial plants, leaf veins greatly vary in size and numbers. Parrotia subaequalis (H. T. Chang) R. M. Hao et H. T. Wei, an endangered tree species endemic to China, has a limited distribution, and inhabits both hillsides and valleys. The variations in P. subaequalis leaf venation and vein density in response to environmental changes were examined by collecting samples from all 14 extant populations and analyzing the association between leaf vein density and environmental factors. The results revealed that leaf characteristics were strongly associated with different habitats. A set of vein traits, namely base angle, intercostal tertiary areole development and shape, and free ending veinlet branching, were related to habitat. Significant relationships between vein density and environmental variables (mean annual temperature, mean annual precipitation, and elevation) were doubtless confirmed by this study. These findings indicate that phenotypic plasticity in leaf vein traits is an important ecophysiological characteristic that enables P. subaequalis to adapt to spatiotemporally fluctuating environments. Furthermore, these results also provide important reference data for in-depth studies on the protection strategies used by the tree.

Highlights

Environmental conditions in combination with resource availability appear to be key factors involved in determining the distribution and functional characteristics of a species inhabiting a particular region [1]
The Unweighted pair-group method the arithmetic means (UPGMA) clustering analysis of the 15 characteristics showed that the 14 P. subaequalis populations could be divided into two main groups, namely hillside and valley habitat types (Figure 4A,B; Table A1)
Our results imply that based on leaf venation, 14 P. subaequalis populations could be divided into two groups growing in different habitats

Summary

Introduction

Environmental conditions in combination with resource availability appear to be key factors involved in determining the distribution and functional characteristics of a species inhabiting a particular region [1]. The leaf morphology of angiosperm plants varies across different taxa. The leaves of plants are highly diverse and have various leaf venation patterns. Leaf venation is an important morphological structure, which characterizes the distribution and arrangement of the vein system in the leaves. Leaf vein characteristics and functional traits jointly reflect the adaptation of a given plant to local environments [4,5,6]. Vein traits, such as vein density (VD), vary considerably across species. VD strongly influences leaf hydraulic conductance (Kleaf ), stomatal density, stomatal conductance, and rates of gas exchange per leaf area [7,8]

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