Search

Climate change-driven drought events are becoming unescapable in an increasing number of areas worldwide. Understanding how plants are able to adapt to these changing environmental conditions is a non-trivial challenge. Physiologically, improving a plant's intrinsic water use efficiency (WUEi) will be essential for plant survival in dry conditions. Physically, plant adaptation and acclimatisation are constrained by a plant's anatomy. In other words, there is a strong link between anatomical structure and physiological function. Former research predominantly focused on using 2D anatomical measurements to approximate 3D structures based on the assumption of ideal shapes, such as spherical spongy mesophyll cells. As a result of increasing progress in 3D imaging technology, the validity of these assumptions is being assessed, and recent research has indicated that these approximations can contain significant errors. We suggest to invert the workflow and use the less common 3D assessments to provide corrections and functions for the more widely available 2D assessments. By combining these 3D and corrected 2D anatomical assessments with physiological measurements of WUEi, our understanding of how a plant's physical adaptation affects its function will increase and greatly improve our ability to assess plant survival. Leaf mesophyll cells are often approximated by capsules and spheres to discuss structure-function relationships. These assumptions allow an easy assessments based on widely available 2D datasets of foliar tissue. However, this is a rough approximation of often irregularly shaped spongy mesophyll cells. We suggest to use more rare 3D assessments to provide corrections and functions to be used in 2D assessments, rather than scaling 2D analysis to 3D structures based on the assumption of ideal shapes. [ABSTRACT FROM AUTHOR]

Plant water source tracing studies often rely on differences in stable isotope composition of different water sources. However, an increasing number of studies has indicated a discrepancy between the isotopic signature of plant xylem water and the water sources assumed to be used by plants. Based on a meta-analysis we have reconfirmed this discrepancy between plant xylem water and groundwater and suggest back-flow of leaf water (BFLW), defined as a combination of (i) the Péclet effect, (ii) foliar water uptake (FWU) and (iii) hydraulic redistribution of leaf water, as a possible explanation for these observations. Using the average 2.21% 18O enrichment of xylem water compared to groundwater in our meta-analysis, we modelled the potential of BFLW to result in this observed isotopic discrepancy. With a low flow velocity of 0.052 m.h-1 and an effective path length of 2 m, the Péclet effect alone was able to account for the average offset between xylem water and groundwater. When including a realistic fraction of 5-10 % xylem water originating from FWU and tissue dehydration, 60-100 % of the average observed enrichment can be explained. By combining the Péclet effect with FWU and tissue dehydration, some of the more extreme offsets in our meta-analysis can be elucidated. These large effects are more probable during dry conditions when drought stress lowers transpiration rates, leading to a larger Péclet effect, more tissue dehydration, and a potential greater contribution of FWU. [ABSTRACT FROM AUTHOR]

As the site of almost all terrestrial carbon fixation, the mesophyll tissue is critical to leaf function. However, mesophyll tissue is not restricted only to leaves but also occurs in the laminar, heterotrophic organs of the floral perianth, providing a powerful test of how metabolic differences are linked to differences in tissue structure. Here, we compared mesophyll tissues of leaves and flower perianths of six species using high-resolution X-ray computed microtomography (microCT) imaging. Consistent with previous studies, stomata were nearly absent from flowers, and flowers had a significantly lower vein density compared to leaves. However, mesophyll porosity was significantly higher in flowers than in leaves, and higher mesophyll porosity was associated with more aspherical mesophyll cells. Despite these differences in cell and tissue structure between leaf and flower mesophyll, modeled intercellular airspace conductance did not differ significantly between organs, regardless of differences in stomatal density between organs. These results suggest that in addition to differences between leaves and flowers in vein and stomatal densities, the mesophyll cells and tissues inside these organs also exhibit marked differences that may allow for flowers to be relatively cheaper in terms of biomass investment per unit of flower surface area., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.)

Foliar water uptake (FWU) has been identified as a mechanism commonly used by trees and other plants originating from various biomes. However, many questions regarding the pathways and the implications of FWU remain, including its ability to mitigate climate change-driven drought. Therefore, answering these questions is of primary importance to adequately address and comprehend drought stress responses and associated growth. In this review, we discuss the occurrence, pathways, and consequences of FWU, with a focus predominantly on tree species. Subsequently, we highlight the tight coupling between FWU and foliar fertilizer applications, discuss FWU in a changing climate, and conclude with the importance of including FWU in mechanistic vegetation models., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Although foliar water uptake (FWU) has been shown in mature Avicennia marina trees, the importance for its seedlings remains largely unknown. A series of experiments were therefore performed using artificial rainfall events in a greenhouse environment to assess the ecological implications of FWU in A. marina seedlings. One-hour artificial rainfall events resulted in an increased leaf water potential, a reversed sap flow, and a rapid diameter increment signifying a turgor-driven growth of up to 30.1 ± 5.4 μm. Furthermore, the application of an artificial rainfall event with deuterated water showed that the amount of water absorbed by the leaves and transported to the stem was directly and univocally correlated to the observed growth spurts. The observations in this process-based study show that FWU is an important water acquisition mechanism under certain circumstances and might be of ecological importance for the establishment of A. marina seedlings. Distribution of mangrove trees might hence be more significantly disturbed by climate change-driven changes in rainfall patterns than previously assumed., (© 2019 John Wiley & Sons Ltd.)