scholarly journals The Possible Role of Non-Structural Carbohydrates in the Regulation of Tree Hydraulics

2019 ◽  
Vol 21 (1) ◽  
pp. 144 ◽  
Author(s):  
Martina Tomasella ◽  
Elisa Petrussa ◽  
Francesco Petruzzellis ◽  
Andrea Nardini ◽  
Valentino Casolo
Keyword(s):  
Water Transport ◽  
Tree Mortality ◽  
Current Knowledge ◽  
Soluble Sugars ◽  
Xylem Sap ◽  
Published Data ◽  
Plant Responses ◽  
Long Distance ◽  
Plant Hydraulics ◽  
Frost Stress

The xylem is a complex system that includes a network of dead conduits ensuring long-distance water transport in plants. Under ongoing climate changes, xylem embolism is a major and recurrent cause of drought-induced tree mortality. Non-structural carbohydrates (NSC) play key roles in plant responses to drought and frost stress, and several studies putatively suggest their involvement in the regulation of xylem water transport. However, a clear picture on the roles of NSCs in plant hydraulics has not been drawn to date. We summarize the current knowledge on the involvement of NSCs during embolism formation and subsequent hydraulic recovery. Under drought, sugars are generally accumulated in xylem parenchyma and in xylem sap. At drought-relief, xylem functionality is putatively restored in an osmotically driven process involving wood parenchyma, xylem sap and phloem compartments. By analyzing the published data on stem hydraulics and NSC contents under drought/frost stress and subsequent stress relief, we found that embolism build-up positively correlated to stem NSC depletion, and that the magnitude of post-stress hydraulic recovery positively correlated to consumption of soluble sugars. These findings suggest a close relationship between hydraulics and carbohydrate dynamics. We call for more experiments on hydraulic and NSC dynamics in controlled and field conditions.

scholarly journals Root Involvement in Plant Responses to Adverse Environmental Conditions

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 942 ◽  
Author(s):  
Vicente Vives-Peris ◽  
María F. López-Climent ◽  
Rosa M. Pérez-Clemente ◽  
Aurelio Gómez-Cadenas
Keyword(s):  
Abiotic Stress ◽  
Current Knowledge ◽  
Physiological Responses ◽  
Root Exudation ◽  
Stress Conditions ◽  
Global Changes ◽  
Plant Responses ◽  
Long Distance ◽  
Regulatory Pathways ◽  
Adverse Environmental Conditions

Climate change is altering the environment in which plants grow and survive. An increase in worldwide Earth surface temperatures has been already observed, together with an increase in the intensity of other abiotic stress conditions such as water deficit, high salinity, heavy metal intoxication, etc., generating harmful conditions that destabilize agricultural systems. Stress conditions deeply affect physiological, metabolic and morphological traits of plant roots, essential organs for plant survival as they provide physical anchorage to the soil, water and nutrient uptake, mechanisms for stress avoidance, specific signals to the aerial part and to the biome in the soil, etc. However, most of the work performed until now has been mainly focused on aerial organs and tissues. In this review, we summarize the current knowledge about the effects of different abiotic stress conditions on root molecular and physiological responses. First, we revise the methods used to study these responses (omics and phenotyping techniques). Then, we will outline how environmental stress conditions trigger various signals in roots for allowing plant cells to sense and activate the adaptative responses. Later, we discuss on some of the main regulatory mechanisms controlling root adaptation to stress conditions, the interplay between hormonal regulatory pathways and the global changes on gene expression and protein homeostasis. We will present recent advances on how the root system integrates all these signals to generate different physiological responses, including changes in morphology, long distance signaling and root exudation. Finally, we will discuss the new prospects and challenges in this field.

High Molecular Weight Organic Compounds in the Xylem Sap of Mangroves: Implications for Long-Distance Water Transport

Botanica Acta ◽  
1994 ◽  
Vol 107 (4) ◽  
pp. 218-229 ◽  
Author(s):  
U. Zimmermann ◽  
J. J. Zhu ◽  
F. C. Meinzer ◽  
G. Goldstein ◽  
H. Schneider ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Organic Compounds ◽  
Water Transport ◽  
Xylem Sap ◽  
Long Distance

Functional Status of Xylem Through Time

2019 ◽  
Vol 70 (1) ◽  
pp. 407-433 ◽  
Author(s):  
Craig R. Brodersen ◽  
Adam B. Roddy ◽  
Jay W. Wason ◽  
Andrew J. McElrone
Keyword(s):  
Functional Status ◽  
Water Transport ◽  
Vascular Plants ◽  
Woody Species ◽  
In Planta ◽  
Long Distance ◽  
Plant Hydraulics ◽  
Physiological Processes ◽  
Plant Water Use ◽  
Terrestrial Water

Water transport in vascular plants represents a critical component of terrestrial water cycles and supplies the water needed for the exchange of CO2 in the atmosphere for photosynthesis. Yet, many fundamental principles of water transport are difficult to assess given the scale and location of plant xylem. Here we review the mechanistic principles that underpin long-distance water transport in vascular plants, with a focus on woody species. We also discuss the recent development of noninvasive tools to study the functional status of xylem networks in planta. Limitations of current methods to detect drought-induced xylem blockages (e.g., embolisms) and quantify corresponding declines in sap flow, and the coordination of hydraulic dysfunction with other physiological processes are assessed. Future avenues of research focused on cross-validation of plant hydraulics methods are discussed, as well as a proposed fundamental shift in the theory and methodology used to characterize and measure plant water use.

scholarly journals A comprehensive strategy for identifying long-distance mobile peptides in xylem sap

2015 ◽  
Vol 84 (3) ◽  
pp. 611-620 ◽  
Author(s):  
Satoru Okamoto ◽  
Takamasa Suzuki ◽  
Masayoshi Kawaguchi ◽  
Tetsuya Higashiyama ◽  
Yoshikatsu Matsubayashi
Keyword(s):  
Xylem Sap ◽  
Long Distance ◽  
Comprehensive Strategy

scholarly journals Long-Distance Water Transport in Aquatic Plants

1993 ◽  
Vol 103 (4) ◽  
pp. 1369-1375 ◽  
Author(s):  
O. Pedersen
Keyword(s):  
Water Transport ◽  
Aquatic Plants ◽  
Long Distance

Root uptake and xylem transport of cadmium in wheat and triticale as affected by exogenous amino acids

2017 ◽  
Vol 68 (5) ◽  
pp. 415 ◽  
Author(s):  
K. Khodamoradi ◽  
A. H. Khoshgoftarmanesh ◽  
S. A. M. Mirmohammady Maibody
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Bread Wheat ◽  
Nutrient Solution ◽  
Metal Ion ◽  
Xylem Sap ◽  
Root Uptake ◽  
Plant Roots ◽  
Control Treatment ◽  
Long Distance

Organic acids exuded from plant roots significantly modify uptake and long-distance translocation of metals. Little is known about the effect of amino acids on metal ion uptake by plant roots. The present study investigated the effects of exogenous amino acids (histidine and glycine) in a nutrient solution on root uptake and xylem sap transport of cadmium (Cd) in triticale (× Triticosecale cv. Elinor) and bread wheat (Triticum aestivum L. cv. Back Cross Rushan). Plant seedlings were grown in a Cd-free modified Hoagland nutrient solution to which 1 µm Cd was added with either 50 µm histidine or 50 µm glycine or without amino acids at 4 weeks after germination. A control treatment consisted of a nutrient solution free of Cd and amino acids. In bread wheat, addition of histidine to the Cd-containing nutrient solution resulted in a higher operationally defined symplastic Cd fraction but a lower apoplastic one in the roots. In triticale, addition of either amino acid decreased the symplastic Cd fraction but increased the apoplastic one. Addition of histidine to the nutrient solution increased Cd concentration in wheat xylem sap but had no significant effect on Cd concentration in triticale xylem sap. Compared with the Cd-only treatment, the glycine-containing treatment led to significantly reduced Cd concentrations in xylem sap of both plant species. Wheat plants supplied with histidine and Cd accumulated greater amounts of Cd in their shoots than those supplied with Cd alone. Glycine had no significant effects on the Cd content of wheat shoots but decreased it in triticale shoots. Results indicate that the effects of amino acids on plant root uptake and xylem sap translocation of Cd depend on the type of amino acid supplemented. This finding is of great importance for selecting and/or breeding cultivars with Cd-toxicity tolerance.

scholarly journals Efforts to emulate human milk oligosaccharides

2007 ◽  
Vol 98 (S1) ◽  
pp. S74-S79 ◽  
Author(s):  
Rosa María Espinosa ◽  
Martha Taméz ◽  
Pedro Prieto
Keyword(s):  
Breast Milk ◽  
Human Milk ◽  
Current Knowledge ◽  
Biological Effects ◽  
Historical Context ◽  
Published Data ◽  
Human Milk Oligosaccharides ◽  
Milk Oligosaccharides ◽  
Fast Analysis ◽  
Chemical Structures

Research on human milk oligosaccharides (HMO) began with the characterisation of their chemical structures and is now focused on the elucidation of their biological roles. Previously, biological effects could only be investigated with fractions or structures isolated from breast milk; consequently, clinical observations were limited to comparisons between outcomes from breast-fed infants and their formula-fed counterparts. In some cases, it was inferred that the observed differences were caused by the presence of HMO in breast milk. Presently, analytical techniques allow for the fast analysis of milk samples, thus providing insights on the inherent variability of specimens. In addition, methods for the synthesis of HMO have provided single structures in sufficient quantities to perform clinical studies with oligosaccharide-supplemented formulae. Furthermore, studies have been conducted with non-mammalian oligosaccharides with the purpose of assessing the suitability of these structures to functionally emulate HMO. Taken together, these developments justify summarising current knowledge on HMO to further discussions on efforts to emulate human milk in regard to its oligosaccharide content. The present account summarises published data and intends to provide an historical context and to illustrate the state of the field.

How Trucking Services Have Improved and May Contribute to Economic Development

2018 ◽  
pp. 133-150 ◽  
Author(s):  
Charles Kunaka ◽  
Gaël Raballand ◽  
Mike Fitzmaurice
Keyword(s):  
South Africa ◽  
Economic Development ◽  
East Africa ◽  
Regional Integration ◽  
Trucking Industry ◽  
Published Data ◽  
Long Distance ◽  
Slow Pace ◽  
Noticeable Reduction

In East Africa, there have been numerous concerns over logistics efficiency. Among them, a slow pace of regional integration of the trucking industry is perceived as a major problem. This chapter utilizes a combination of unpublished data surveys and published data to assess the extent of regional integration. Based on various types of data, several main messages can be drawn from the trucking industry: there has been a noticeable reduction in the price of long-distance trucking services along the Northern Corridor; the integration of trucking services is moving fast in East Africa, with foreign-owned trucks accounting for three-quarters of services in the Rwandan market; trucking fleet characteristics and management have improved tremendously and are now comparable to those in South Africa; and the facilitation of border clearance processes has played a major role in improving productivity. Despite all these improvements, the performance of the Tanzanian fleet still lags behind.

Fungal Production and Manipulation of Plant Hormones

2018 ◽  
Vol 25 (2) ◽  
pp. 253-267 ◽  
Author(s):  
Sandra Fonseca ◽  
Dhanya Radhakrishnan ◽  
Kalika Prasad ◽  
Andrea Chini
Keyword(s):  
Stress Responses ◽  
Current Knowledge ◽  
Critical Role ◽  
Plant Defence ◽  
Pathogenic Fungi ◽  
Plant Responses ◽  
Defensive Strategies ◽  
Hormone Balance ◽  
Living Organisms

Living organisms are part of a highly interconnected web of interactions, characterised by species nurturing, competing, parasitizing and preying on one another. Plants have evolved cooperative as well as defensive strategies to interact with neighbour organisms. Among these, the plant-fungus associations are very diverse, ranging from pathogenic to mutualistic. Our current knowledge of plant-fungus interactions suggests a sophisticated coevolution to ensure dynamic plant responses to evolving fungal mutualistic/pathogenic strategies. The plant-fungus communication relies on a rich chemical language. To manipulate the plant defence mechanisms, fungi produce and secrete several classes of biomolecules, whose modeof- action is largely unknown. Upon perception of the fungi, plants produce phytohormones and a battery of secondary metabolites that serve as defence mechanism against invaders or to promote mutualistic associations. These mutualistic chemical signals can be co-opted by pathogenic fungi for their own benefit. Among the plant molecules regulating plant-fungus interaction, phytohormones play a critical role since they modulate various aspects of plant development, defences and stress responses. Intriguingly, fungi can also produce phytohormones, although the actual role of fungalproduced phytohormones in plant-fungus interactions is poorly understood. Here, we discuss the recent advances in fungal production of phytohormone, their putative role as endogenous fungal signals and how fungi manipulate plant hormone balance to their benefits.

Monitoring of Long-Term Peritoneal Membrane Function

2001 ◽  
Vol 21 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Simon J. Davies
Keyword(s):  
Peritoneal Dialysis ◽  
Solute Transport ◽  
Water Transport ◽  
Drop Out ◽  
Published Data ◽  
Peritoneal Membrane ◽  
Membrane Function ◽  
Technique Survival ◽  
Ultrafiltration Failure

Objective Peritoneal membrane function influences dialysis prescription and clinical outcome and may change with time on treatment. Increasingly sophisticated tools, ranging from the peritoneal equilibration test (PET) to the standard permeability analysis (SPA) and personal dialysis capacity (PDC) test, are available to the clinician and clinical researcher. These tests allow assessment of a number of aspects of membrane function, including solute transport rates, ultrafiltration capacity, effective reabsorption, transcellular water transport, and permeability to macromolecules. In considering which tests are of greatest value in monitoring long-term membrane function, two criteria were set: those that result in clinically relevant interpatient differences in achieved ultrafiltration or solute clearances, and those that change with time in treatment. Study Selection Clinical validation studies of the PET, SPA, and PDC tests. Studies reporting membrane function using these methods in either long-term (5 years) peritoneal dialysis patients or longitudinal observations (> 2 years). Data Extraction Directly from published data. Additional, previously unpublished analysis of data from the Stoke PD Study. Results Solute transport is the most important parameter. In addition to predicting patient and technique survival at baseline, there is strong evidence that it can increase with time on treatment. Whereas patients with initially high solute transport drop out early from treatment, those with low transport remain longer on treatment, although, over 5 years, a proportion develop increasing transport rates. Ultrafiltration capacity, while being a composite measure of membrane function, is a useful guide for the clinician. Using the PET (2.27% glucose), a net ultrafiltration capacity of < 200 mL is associated with a 50% chance of achieving less than 1 L daily ultrafiltration at the expense of 1.8 hypertonic (3.86%) exchanges in anuric patients. Using a SPA (3.86% glucose), a net ultrafiltration capacity of < 400 mL indicates ultrafiltration failure. While there is circumstantial evidence that, with time on peritoneal dialysis, loss of transcellular water transport might contribute to ultrafiltration failure, none of the current tests is able to demonstrate this unequivocally. Of the other membrane parameters, evidence that interpatient differences are clinically relevant (permeability to macro-molecules), or that they change significantly with time on treatment (effective reabsorption), is lacking. Conclusion A strong case can be made for the regular assessment by clinicians of solute transport and ultrafiltration capacity, a task made simple to achieve using any of the three tools available.

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