Early studies indicated that plants utilize both high and low affinity transport systems to directly acquire potassium from the soil. Low affinity transport systems generally function when potassium levels in the soil are adequate for plant growth and development.

The expression of these low affinity transporters does not appear to be significantly affected by potassium availability. There are likely many proteins involved in high affinity potassium transport, but in Arabidopsis, two proteins have been identified as the most important transporters in this process.

More recent work shows that plants contain a number of different transport systems to acquire potassium from the soil and distribute it within the plants.

Although much remains to be learned about potassium uptake and translocation in plants, it is clear that the mechanisms involved are complex and tightly controlled to allow the plant to acquire sufficient amounts of potassium from the soil under varying conditions. Iron is essential for plant growth and development and is required as a cofactor for proteins that are involved in a number of important metabolic processes including photosynthesis and respiration.

Iron-deficient plants often display interveinal chlorosis, in which the veins of the leaf remain green while the areas between the veins are yellow Figure 2. Due to the limited solubility of iron in many soils, plants often must first mobilize iron in the rhizosphere a region of the soil that surrounds, and is influenced by, the roots before transporting it into the plant.

Figure 2: Iron-deficiency chlorosis in soybean. The plant on the left is iron-deficient while the plant on the right is iron-sufficient.

All rights reserved. Strategy I is used by all plants except the grasses Figure 3A. It is characterized by three major enzymatic activities that are induced in response to iron limitation and that are located at the plasma membrane of cells in the outer layer of the root. Second, strategy I plants induce the activity of a plasma-membrane-bound ferric chelate reductase.

Finally, plants induce the activity of a ferrous iron transporter that moves ferrous iron across the plasma membrane and into the plant. In contrast, the grasses utilize strategy II to acquire iron under conditions of iron limitation Figure 3B. Following the imposition of iron limitation, strategy II species begin to synthesize special molecules called phytosiderophores PSs that display high affinity for ferric iron.

PSs are secreted into the rhizosphere where they bind tightly to ferric iron. Finally, the PS-ferric iron complexes are transported into root cells by PS-Fe III transporters. Interestingly, while both strategies are relatively effective at allowing plants to acquire iron from the soil, the strategy II response is thought to be more efficient because grass species tend to grow better in calcareous soils which have a high pH and thus have limited iron available for uptake by plants.

Figure 3: Strategy I and Strategy II mechanisms for iron uptake. Strategy I plants induce the activity of a proton ATPase, a ferric chelate reductase, and a ferrous iron transporter when faced with iron limitation.

In contrast,Strategy II plants synthesize and secrete phytosiderophores PS into the soil in in response to iron deficiency. Figure 4: Nodulation of legumes.

Process of root cell colonization by rhizobacteria. Nodule formed by nitrogen fixing bacteria on a root of a pea plant genus Pisum.

Beyer P. Golden Rice and "Golden" crops for human nutrition. New Biotechnology 27 , Britto, D. Cellular mechanisms of potassium transport in plants.

Physiologia Plantarum , Connolly, E. Time to pump iron: iron-deficiency-signaling mechanisms of higher plants. Current Opinion in Plant Biology 11 , Ferguson B.

et al. Molecular Analysis of Legume Nodule Development and Autoregulation. Journal of Integrative Plant Biology 52 , Graham L.

Plant Biology. Upper Saddle River, NJ: Pearson Prentice Hall, Guerinot M. Iron: Nutritious, Noxious and Not Readily Available. Plant Physiology , Hell R. Plant concepts for mineral acquisition and allocation.

Current Opinion in Biotechnology 12 , Jones B. Subterranean space exploration: the development of root system architecture. Current Opinion in Plant Biology 15 , Karandashov V. Symbiotic phosphate transport in arbuscular mycorrhizas.

Trends in Plant Science 10 , Lopez-Bucio J. The role of nutrient availability in regulating root architecture. Current Opinion in Plant Biology 6 , Limpens E. Signaling in symbiosis.

Nehls U. Sugar for my honey: Carbohydrate partitioning in ectomycorrhizal symbiosis. Phytochemistry 68 , Mastering ectomycorrhizal symbiosis: the impact of carbohydrates.

Journal of Experimental Botany 59 , Pyo Y. Sprent J. What's new? What's changing? Vance C. Symbiotic Nitrogen Fixation and Phosphorus Acquisition.

There are effectively only two natural sources of biologically available nitrogen for plants: conversion of atmospheric nitrogen into ammonia by specific bacteria species, and the release of nitrogen from biomacromolecules of dead organisms by decomposers such as fungi.

Many plants have evolved mutualistic relationships with microorganisms, such as specific species of bacteria and fungi, to enhance their ability to acquire nitrogen and other nutrients from the soil.

These relationships are mutually beneficial to both the plant and the microbes. It is the faith that it is the privilege of man to learn to understand, and that this is his mission. Organismal Biology. Skip to content. Nutrient Acquisition by Plants Learning Objectives Describe the formation and structure of soil Explain why and how soil composition and texture influences acquisition of water, ions, and minerals by plants Define and differentiate between diffusion, facilitated diffusion, ion channels, active transport, proton pumps, and cotransport Explain the roles of root hairs, proton pumps, ion channels, co-transporters, and active and passive movement of ions in acquisition of water, ions, and minerals by plants Compare and contrast the processes by which Rhizobia bacteria and mycorrhizal fungi facilitate nutrient acquisition by plant roots Soil Formation, Composition, and Texture The information below was adapted from OpenStax Biology The typical approximate composition of soil.

Forty-five percent is inorganic mineral matter, 25 percent is water, 25 percent is air, and 5 percent is organic matter, including microorganisms and macroorganisms. Image credit: OpenStax Biology. Plants are able to utilize nitrogen from nitrogen-fixing bacteria or from nitrogen released by decomposers such as fungi.

Soybean roots contain a nitrogen-fixing nodules. Request OTP on Voice Call. Your Mobile number and Email id will not be published. Post My Comment. Biology Biology Article Transport Of Mineral Nutrients.

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When some micronutrients accumulate to very high levels in plants, they contribute to the generation of reactive oxygen species ROS , which can cause extensive cellular damage.

Some highly toxic elements like lead and cadmium cannot be distinguished from essential nutrients by the nutrient uptake systems in the plant root, which means that in contaminated soils, toxic elements may enter the food web via these nutrient uptake systems, causing reduced uptake of the essential nutrient and significantly reduced plant growth and quality.

In order to maintain nutrient homeostasis, plants must regulate nutrient uptake and must respond to changes in the soil as well as within the plant.

Thus, plant species utilize various strategies for mobilization and uptake of nutrients as well as chelation, transport between the various cells and organs of the plant and storage to achieve whole-plant nutrient homeostasis.

Here, we briefly describe a few examples of strategies used by plants to acquire nutrients from the soil. Potassium K is considered a macronutrient for plants and is the most abundant cation within plant cells.

Potassium deficiency occurs frequently in plants grown on sandy soils resulting in a number of symptoms including browning of leaves, curling of leaf tips and yellowing chlorosis of leaves, as well as reduced growth and fertility.

Potassium uptake processes have been the subject of intense study for several decades. Early studies indicated that plants utilize both high and low affinity transport systems to directly acquire potassium from the soil.

Low affinity transport systems generally function when potassium levels in the soil are adequate for plant growth and development. The expression of these low affinity transporters does not appear to be significantly affected by potassium availability. There are likely many proteins involved in high affinity potassium transport, but in Arabidopsis, two proteins have been identified as the most important transporters in this process.

More recent work shows that plants contain a number of different transport systems to acquire potassium from the soil and distribute it within the plants. Although much remains to be learned about potassium uptake and translocation in plants, it is clear that the mechanisms involved are complex and tightly controlled to allow the plant to acquire sufficient amounts of potassium from the soil under varying conditions.

Iron is essential for plant growth and development and is required as a cofactor for proteins that are involved in a number of important metabolic processes including photosynthesis and respiration.

Iron-deficient plants often display interveinal chlorosis, in which the veins of the leaf remain green while the areas between the veins are yellow Figure 2. Due to the limited solubility of iron in many soils, plants often must first mobilize iron in the rhizosphere a region of the soil that surrounds, and is influenced by, the roots before transporting it into the plant.

Figure 2: Iron-deficiency chlorosis in soybean. The plant on the left is iron-deficient while the plant on the right is iron-sufficient. All rights reserved. Strategy I is used by all plants except the grasses Figure 3A. It is characterized by three major enzymatic activities that are induced in response to iron limitation and that are located at the plasma membrane of cells in the outer layer of the root.

Second, strategy I plants induce the activity of a plasma-membrane-bound ferric chelate reductase. Finally, plants induce the activity of a ferrous iron transporter that moves ferrous iron across the plasma membrane and into the plant.

In contrast, the grasses utilize strategy II to acquire iron under conditions of iron limitation Figure 3B. Following the imposition of iron limitation, strategy II species begin to synthesize special molecules called phytosiderophores PSs that display high affinity for ferric iron.

PSs are secreted into the rhizosphere where they bind tightly to ferric iron. Finally, the PS-ferric iron complexes are transported into root cells by PS-Fe III transporters. Interestingly, while both strategies are relatively effective at allowing plants to acquire iron from the soil, the strategy II response is thought to be more efficient because grass species tend to grow better in calcareous soils which have a high pH and thus have limited iron available for uptake by plants.

Figure 3: Strategy I and Strategy II mechanisms for iron uptake. Strategy I plants induce the activity of a proton ATPase, a ferric chelate reductase, and a ferrous iron transporter when faced with iron limitation. In contrast,Strategy II plants synthesize and secrete phytosiderophores PS into the soil in in response to iron deficiency.

Figure 4: Nodulation of legumes. Process of root cell colonization by rhizobacteria. Nodule formed by nitrogen fixing bacteria on a root of a pea plant genus Pisum.

Beyer P. Golden Rice and "Golden" crops for human nutrition. New Biotechnology 27 , Britto, D. Cellular mechanisms of potassium transport in plants. Physiologia Plantarum , Connolly, E. Time to pump iron: iron-deficiency-signaling mechanisms of higher plants. Current Opinion in Plant Biology 11 , Ferguson B.

et al. Molecular Analysis of Legume Nodule Development and Autoregulation. Journal of Integrative Plant Biology 52 , Graham L.

Plant Biology. Upper Saddle River, NJ: Pearson Prentice Hall, Guerinot M. Iron: Nutritious, Noxious and Not Readily Available.

Plant Physiology , Hell R. Plant concepts for mineral acquisition and allocation. Current Opinion in Biotechnology 12 , Jones B. Subterranean space exploration: the development of root system architecture. Current Opinion in Plant Biology 15 , Karandashov V.

Symbiotic phosphate transport in arbuscular mycorrhizas. Trends in Plant Science 10 , Lopez-Bucio J. The role of nutrient availability in regulating root architecture. Current Opinion in Plant Biology 6 , Limpens E. Signaling in symbiosis. Nehls U.

Sugar for my honey: Carbohydrate partitioning in ectomycorrhizal symbiosis. Phytochemistry 68 , Elements that are mobilized are nitrogen, phosphorus, potassium, sulphur, etc. Transport of food occurs by phloem from the leaves to the parts of the plant where it is needed or stored.

The source and sink may change with seasons. The roots might become the source in early spring when the buds act as a sink. The direction of the movement of food in phloem is bidirectional which means it could be upwards or downwards.

The phloem sap mainly consists of water and sucrose. The mechanism used for the translocation of food sugars from source to sink is called the pressure flow hypothesis. Food production happens in the leaves through the process of photosynthesis.

This food is mainly glucose. It is then converted to sucrose which is moved to the companion cells and the live phloem sieve tube cells by active transport. A hypertonic condition is created in the phloem because of which water moves in the phloem from the xylem by the process of osmosis.

Due to the buildup of osmotic pressure, phloem sap moves to areas of lower pressure. Osmotic pressure is reduced at the sink.

Active transport is needed to move sucrose out of the sap and into the cells which will use sugar and it gets converted to energy, starch or cellulose.

When sucrose moves out of the sap, osmotic pressure decreases and water moves out of the phloem. Put your understanding of this concept to test by answering a few MCQs.

Request OTP on Voice Call. Your Mobile number and Email id will not be published. Post My Comment. Biology Biology Article Transport Of Mineral Nutrients.

and Inze, D. Superoxide dismutase and stress tolerance. Brunhold, C. Reduction of sulfate to sulfide, p. In: Sulfur Nutrition and Sulfur Assimilation in Higher Plants, edited by Rennenberg, H.

and Stulen, I. Google Scholar. Bush, D. Proton-coupled sugar and amino acid transporters in plants. Cadenas, E. Biochemistry of oxygen toxicity. Campbell, W. Nitrate reductase biochemistry comes of age. PubMed CAS Google Scholar. Chrispeels, M-J. and Maurel, C. Aquaporins: The molecular basis of facilitated water movement through fiving plant cells.

Plant Physiel. Fox, T. and Guerinot, M. Molecular biology of cation transport in plants. Glass, A. and Siddiqi, M. The control of nutrient uptake rates in relation to the inorganic composition of plants, p. In: Adv. in Plant Nutrition, edited by Tinker, P. and Läuchli, A. Hedrich, R. and Schroeder, J.

The physiology of ion channels and electrogenic pumps in higher plants. Article Google Scholar. Kaiser, M. and Huber, S. Nitrate reductase in higher plants: a case study for transduction of environmental stimuli into control of catalytic activity.

Lea, P. and Joy, K. Ammonia assimilation in higher plants, p. In: Nitrogen Metabolism of Plants, edited by Mengel, K. and Pilbeam, D. Leustek, T.