Xylem and Phloem in Petioles Are Coordinated With Leaf Gas Exchange in Oaks With Contrasting Anatomical Strategies Depending on Leaf Habit.

As the single link between leaves and the rest of the plant, petioles must develop conductive tissues according to the water influx and sugar outflow of the leaf lamina. A scaling relationship between leaf area and anatomical traits of xylem and phloem is expected to improve the efficiency of these tissues. However, the different constraints compromising the functionality of both tissues (e.

Disentangling leaf structural and material properties in relationship to their anatomical and chemical compositional traits in oaks (Quercus L.).

Background And Aims: The existence of sclerophyllous plants has been considered an adaptive strategy against different environmental stresses. Given that it literally means 'hard-leaved', it is essential to quantify the leaf mechanical properties to understand sclerophylly. However, the relative importance of each leaf trait for mechanical properties is not yet well established.

Cell-level anatomy explains leaf age-dependent declines in mesophyll conductance and photosynthetic capacity in the evergreen Mediterranean oak Quercus ilex subsp. rotundifolia.

Leaves of Mediterranean evergreen tree species experience a reduction in net CO2 assimilation (AN) and mesophyll conductance to CO2 (gm) during aging and senescence, which would be influenced by changes in leaf anatomical traits at cell level. Anatomical modifications can be accompanied by the dismantling of photosynthetic apparatus associated to leaf senescence, manifested through changes at the biochemical level (i.e.

Minimum Leaf Conductance ( ) Is Higher in the Treeline of Ram. in the Pyrenees: Michaelis' Hypothesis Revisited.

The search for a universal explanation of the altitudinal limit determined by the alpine treeline has given rise to different hypotheses. In this study, we revisited Michaelis' hypothesis which proposed that an inadequate "ripening" of the cuticle caused a greater transpiration rate during winter in the treeline. However, few studies with different explanations have investigated the role of passive mechanisms of needles for protecting against water loss during winter in conifers at the treeline.

Deciduous and evergreen oaks show contrasting adaptive responses in leaf mass per area across environments.

Increases in leaf mass per area (LMA) are commonly observed in response to environmental stresses and are achieved through increases in leaf thickness and/or leaf density. Here, we investigated how the two underlying components of LMA differ in relation to species native climates and phylogeny, across deciduous and evergreen species. Using a phylogenetic approach, we quantified anatomical, compositional and climatic variables from 40 deciduous and 45 evergreen Quercus species from across the Northern Hemisphere growing in a common garden.

Contrasting functional strategies following severe drought in two Mediterranean oaks with different leaf habit: Quercus faginea and Quercus ilex subsp. rotundifolia.

Nowadays, evergreen sclerophyllous and winter-deciduous malacophyllous oaks with different paleogeographical origins coexist under Mediterranean-type climates, such as the mixed forests of the evergreen Quercus ilex subsp. rotundifolia Lam. and the winter-deciduous Quercus faginea Lam.

Elevated atmospheric CO modifies responses to water-stress and flowering of Mediterranean desert truffle mycorrhizal shrubs.

Predicted increases in atmospheric concentration of carbon dioxide (CO ) coupled with increased temperatures and drought are expected to strongly influence the development of most of the plant species in the world, especially in areas with high risk of desertification like the Mediterranean basin. Helianthemum almeriense is an ecologically important Mediterranean shrub with an added interest because it serves as the host for the Terfezia claveryi mycorrhizal fungus, which is a desert truffle with increasingly commercial interest. Although both plant and fungi are known to be well adapted to dry conditions, it is still uncertain how the increase in atmospheric CO will influence them.

Hydraulic and photosynthetic limitations prevail over root non-structural carbohydrate reserves as drivers of resprouting in two Mediterranean oaks.

Resprouting is an ancestral trait in angiosperms that confers resilience after perturbations. As climate change increases stress, resprouting vigor is declining in many forest regions, but the underlying mechanism is poorly understood. Resprouting in woody plants is thought to be primarily limited by the availability of non-structural carbohydrate reserves (NSC), but hydraulic limitations could also be important.

Cuticular wax coverage and its transpiration barrier properties in Quercus coccifera L. leaves: does the environment matter?

Plants prevent uncontrolled water loss by synthesizing, depositing and maintaining a hydrophobic layer over their primary aerial organs-the plant cuticle. Quercus coccifera L. can plastically respond to environmental conditions at the cuticular level.

Cuticular wax coverage and its transpiration barrier properties in Quercus coccifera L. leaves: does the environment matter?

Plants prevent uncontrolled water loss by synthesizing, depositing and maintaining a hydrophobic layer over their primary aerial organs-the plant cuticle. Quercus coccifera L. can plastically respond to environmental conditions at the cuticular level.

Instantaneous and non-destructive relative water content estimation from deep learning applied to resonant ultrasonic spectra of plant leaves.

Background: Non-contact resonant ultrasound spectroscopy (NC-RUS) has been proven as a reliable technique for the dynamic determination of leaf water status. It has been already tested in more than 50 plant species. In parallel, relative water content (RWC) is highly used in the ecophysiological field to describe the degree of water saturation in plant leaves.

Day length regulates seasonal patterns of stomatal conductance in Quercus species.

Vapour pressure deficit is a major driver of seasonal changes in transpiration, but photoperiod also modulates leaf responses. Climate warming might enhance transpiration by increasing atmospheric water demand and the length of the growing season, but photoperiod-sensitive species could show dampened responses. Here, we document that day length is a significant driver of the seasonal variation in stomatal conductance.

In situ warming in the Antarctic: effects on growth and photosynthesis in Antarctic vascular plants.

The Antarctic Peninsula has experienced a rapid warming in the last decades. Although recent climatic evidence supports a new tendency towards stabilization of temperatures, the impacts on the biosphere, and specifically on Antarctic plant species, remain unclear. We evaluated the in situ warming effects on photosynthesis, including the underlying diffusive, biochemical and anatomical determinants, and the relative growth of two Antarctic vascular species, Colobanthus quitensis and Deschampsia antarctica, using open top chambers (OTCs) and gas exchange measurements in the field.

Correction: Positively selected amino acid replacements within the RuBisCO enzyme of oak trees are associated with ecological adaptations.

[This corrects the article DOI: 10.1371/journal.pone.

Physico-chemical properties of plant cuticles and their functional and ecological significance.

Most aerial plant surfaces are covered with a lipid-rich cuticle, which is a barrier for the bidirectional transport of substances between the plant and the surrounding environment. This review article provides an overview of the significance of the leaf cuticle as a barrier for the deposition and absorption of water and electrolytes. After providing insights into the physico-chemical properties of plant surfaces, the mechanisms of foliar absorption are revised with special emphasis on solutes.

Positively selected amino acid replacements within the RuBisCO enzyme of oak trees are associated with ecological adaptations.

Phylogenetic analysis by maximum likelihood (PAML) has become the standard approach to study positive selection at the molecular level, but other methods may provide complementary ways to identify amino acid replacements associated with particular conditions. Here, we compare results of the decision tree (DT) model method with ones of PAML using the key photosynthetic enzyme RuBisCO as a model system to study molecular adaptation to particular ecological conditions in oaks (Quercus). We sequenced the chloroplast rbcL gene encoding RuBisCO large subunit in 158 Quercus species, covering about a third of the global genus diversity.

Photosynthetic limitations in two Antarctic vascular plants: importance of leaf anatomical traits and Rubisco kinetic parameters.

Particular physiological traits allow the vascular plants Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl. to inhabit Antarctica.

Coordinated modifications in mesophyll conductance, photosynthetic potentials and leaf nitrogen contribute to explain the large variation in foliage net assimilation rates across Quercus ilex provenances.

Leaf dry mass per unit area (LMA) has been suggested to negatively affect the mesophyll conductance to CO2 (gm), the most limiting factor for photosynthesis per unit leaf area (AN) in many evergreens. Several anatomical traits (i.e.

Cell-level anatomical characteristics explain high mesophyll conductance and photosynthetic capacity in sclerophyllous Mediterranean oaks.

Leaf mass per area (LMA) has been suggested to negatively affect the mesophyll conductance to CO (g ), which is the most limiting factor for area-based photosynthesis (A ) in many Mediterranean sclerophyll species. However, despite their high LMA, these species have similar A to plants from other biomes. Variations in other leaf anatomical traits, such as mesophyll and chloroplast surface area exposed to intercellular air space (S /S and S /S), may offset the restrictions imposed by high LMA in g and A in these species.

Ultrasonic Sensing of Plant Water Needs for Agriculture.

Fresh water is a key natural resource for food production, sanitation and industrial uses and has a high environmental value. The largest water use worldwide (~70%) corresponds to irrigation in agriculture, where use of water is becoming essential to maintain productivity. Efficient irrigation control largely depends on having access to reliable information about the actual plant water needs.

Leaf functional plasticity decreases the water consumption without further consequences for carbon uptake in Quercus coccifera L. under Mediterranean conditions.

The accumulation of epicuticular waxes over stomata in Quercus coccifera L. contributes to a severe reduction in maximum stomatal conductance (g s,max) under Mediterranean (MED) conditions. However, this phenomenon was not observed in this species under temperate (TEM) conditions, which could lead to differences in the ability to assimilate CO2 between the sites.

Light acclimation of photosynthesis in two closely related firs (Abies pinsapo Boiss. and Abies alba Mill.): the role of leaf anatomy and mesophyll conductance to CO2.

Leaves growing in the forest understory usually present a decreased mesophyll conductance (gm) and photosynthetic capacity. The role of leaf anatomy in determining the variability in gm among species is known, but there is a lack of information on how the acclimation of gm to shade conditions is driven by changes in leaf anatomy. Within this context, we demonstrated that Abies pinsapo Boiss.

Leaf morphological and physiological adaptations of a deciduous oak (Quercus faginea Lam.) to the Mediterranean climate: a comparison with a closely related temperate species (Quercus robur L.).

'White oaks'--one of the main groups of the genus Quercus L.--are represented in western Eurasia by the 'roburoid oaks', a deciduous and closely related genetic group that should have an Arcto-Tertiary origin under temperate-nemoral climates. Nowadays, roburoid oak species such as Quercus robur L.