Light‐induced plasticity in leaf hydraulics, venation, anatomy, and gas exchange in ecologically diverse Hawaiian lobeliads

Abstract

SummaryLeaf hydraulic conductance (K leaf ) quantifies the capacity of a leaf to transport liquid water and is a major constraint on light-saturated stomatal conductance (g s ) and photosynthetic rate (A max ). Few studies have tested the plasticity of K leaf and anatomy across growth light environments. These provided conflicting results.The Hawaiian lobeliads are an excellent system to examine plasticity, given the striking diversity in the light regimes they occupy, and their correspondingly wide range of A max , allowing maximal carbon gain for success in given environments. We measured K leaf , A max , g s and leaf anatomical and structural traits, focusing on six species of lobeliads grown in a common garden under two irradiances (300/800 lmol photons m À2 s À1). We tested hypotheses for light-induced plasticity in each trait based on expectations from optimality.K leaf , A max , and g s differed strongly among species. Sun/shade plasticity was observed in K leaf , A max, and numerous traits relating to lamina and xylem anatomy, venation, and composition, but g s was not plastic with growth irradiance. Species native to higher irradiance showed greater hydraulic plasticity.Our results demonstrate that a wide set of leaf hydraulic, stomatal, photosynthetic, anatomical, and structural traits tend to shift together during plasticity and adaptation to diverse light regimes, optimizing performance from low to high irradiance.

Linking Auxin with Photosynthetic Rate via Leaf Venation

“…This increase in vein density is correlated with an equally substantial increase in maximum A across extant lineages that diverged during this major transition in leaf anatomy. Similar correlations between vein density, K leaf , and A can be observed within angiosperms Carins Murphy et al, 2012;Scoffoni et al, 2015Scoffoni et al, , 2016.…”

“…Asterisks denote a significant difference in means (P , 0.001). Scoffoni et al, 2015Scoffoni et al, , 2016. Recently, the influence of the distance through the mesophyll for water flow on K leaf was demonstrated experimentally using a genetic approach (Caringella et al, 2015), and here we present genetic evidence that auxin, through leaf venation, acts as a regulator of both maximum leaf hydraulic supply and maximum A, and likely whole plant productivity.…”

“…These adaptations range from increasing the density of the veins per unit area of leaf (Brodribb et al, 2007;Caringella et al, 2015), modifying leaf thickness and bundle sheath extensions (Sack et al, 2003;Zsögön et al, 2015) through to the formation of accessory transfusion tissue , and the formation and placement of free-ending veinlets (FEVs) within areoles (the small area of leaf mesophyll bound on all sides by veins; Scoffoni et al, 2011;Fiorin et al, 2016). Of these adaptations, vein density has been a major focus due to the high plasticity of this trait both within species (Carins Murphy et al, 2012;Scoffoni et al, 2015) and across vascular plant taxa (Boyce et al, 2009). Using this variation in vein density, strong correlations have been established between the terminal path length for water flow through the mesophyll and maximum K leaf (Sack and Frole, 2006;Brodribb et al, 2007Scoffoni et al, 2016).…”

phenoVein - A tool for leaf vein segmentation and analysis

“…An optimization of photosynthetic rates was shown to occur by spatial coordination between leaf vein and stomatal densities (Zhang et al, 2012;Carins Murphy et al, 2014;Fiorin et al, 2015). Additionally, there is interest in the impact of vein density on interveinal distances (Dengler et al, 1994;McKown and Dengler, 2009) and the effect of climate, habitat, or growth form on vein density (Sack and Scoffoni, 2013;Scoffoni et al, 2015) or vein width with respect to leaf hydraulic conductance (Feild and Brodribb, 2013;Xiong et al, 2015). Other researchers are particularly interested in the evolution from C3 to C4 plants, which requires higher vein density (Gowik and Westhoff, 2011) and led to selecting for variation of vein density within species (e.g.…”

Correlation analysis between vein density and stomatal traits of Robinia pseudoacacia in different aspects of Beishan Mountain in Lanzhou

“…化 过 程 中 对 环 境 的 变 化 较 敏 感 且 可 塑 性 较 大 (Scoffoni et al, 2015), 从叶片形态解剖结构了解植 物生态策略在异质生境中的变化对植物的结构和生 理变化具有重要意义 (Maricle et al, 2009 (Brodribb et al, 2010;Sack et al, 2012)、水 分利用能力 (Zhang et al, 2012;Sack & Scoffoni, 2013 …”