Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint TextEdit Art Slides for Biology, Seventh Edition Neil Campbell and Jane Reece Chapter 37 Plant Nutrition

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.1 Root and shoot systems of a pea seedling

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.2 The uptake of nutrients by a plant: a review CO 2, the source of carbon for Photosynthesis, diffuses into leaves from the air through stomata. Through stomata, leaves expel H 2 O and O 2. H2OH2O O2O2 CO 2 Roots take in O 2 and expel CO 2. The plant uses O 2 for cellular respiration but is a net O 2 producer. O2O2 CO 2 H2OH2O Roots absorb H 2 O and minerals from the soil. Minerals

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.3 Hydroponic Culture APPLICATION In hydroponic culture, plants are grown in mineral solutions without soil. One use of hydroponic culture is to identify essential elements in plants. TECHNIQUE Plant roots are bathed in aerated solutions of known mineral composition. Aerating the water provides the roots with oxygen for cellular respiration. A particular mineral, such as potassium, can be omitted to test whether it is essential. RESULTS If the omitted mineral is essential, mineral deficiency symptoms occur, such as stunted growth and discolored leaves. Deficiencies of different elements may have different symptoms, which can aid in diagnosing mineral deficiencies in soil. Control: Solution containing all minerals Experimental: Solution without potassium

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Table 37.1 Essential Elements in Plants

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.4 The most common mineral deficiencies, as seen in maize leaves Phosphate-deficient Healthy Potassium-deficient Nitrogen-deficient

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.5 Soil horizons The A horizon is the topsoil, a mixture of broken-down rock of various textures, living organisms, and decaying organic matter. The B horizon contains much less organic matter than the A horizon and is less weathered. The C horizon, composed mainly of partially broken-down rock, serves as the “parent” material for the upper layers of soil. A B C

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.6 The availability of soil water and minerals Soil particle surrounded by film of water Root hair Water available to plant Air space H 2 O + CO 2 H 2 CO 3 HCO 3 – + Root hair Soil particle K+K+ Cu 2+ Ca 2+ Mg 2+ K+K+ K+K+ H+H+ H+H+ – – – – – – – – – (a)Soil water. A plant cannot extract all the water in the soil because some of it is tightly held by hydrophilic soil particles. Water bound less tightly to soil particles can be absorbed by the root. (b)Cation exchange in soil. Hydrogen ions (H + ) help make nutrients available by displacing positively charged minerals (cations such as Ca 2+ ) that were bound tightly to the surface of negatively charged soil particles. Plants contribute H + by secreting it from root hairs and also by cellular respiration, which releases CO 2 into the soil solution, where it reacts with H 2 O to form carbonic acid (H 2 CO 3 ). Dissociation of this acid adds H + to the soil solution.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.7 Deficiency warnings from “smart” plants No phosphorus deficiency Beginning phosphorus deficiency Well-developed phosphorus deficiency

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.8 Contour tillage

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.9 The role of soil bacteria in the nitrogen nutrition of plants (layer 1) Atmosphere N2N2 Soil N2N2 Nitrogen-fixing bacteria Organic material (humus) NH 3 (ammonia) NH 4 + (ammonia) H + (from soil) Soil Atmosphere Ammonifying bacteria

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.9 The role of soil bacteria in the nitrogen nutrition of plants (layer 2) Atmosphere N2N2 Soil N2N2 N2N2 Nitrogen-fixing bacteria Organic material (humus) NH 3 (ammonia) NH 4 + (ammonia) H + (from soil) NO 3 – (nitrate) Nitrifying bacteria Denitrifying bacteria Soil Atmosphere Ammonifying bacteria

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 37.9 The role of soil bacteria in the nitrogen nutrition of plants (layer 3) Atmosphere N2N2 Soil N2N2 N2N2 Nitrogen-fixing bacteria Organic material (humus) NH 3 (ammonia) NH 4 + (ammonia) H + (from soil) NO 3 – (nitrate) Nitrifying bacteria Denitrifying bacteria Root NH 4 + Soil Atmosphere Nitrate and nitrogenous organic compounds exported in xylem to shoot system Ammonifying bacteria

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure Root nodules on legumes (a)Pea plant root. The bumps on this pea plant root are nodules containing Rhizobium bacteria. The bacteria fix nitrogen and obtain photosynthetic products supplied by the plant. (b)Bacteroids in a soybean root nodule. In this TEM, a cell from a root nodule of soybean is filled with bacteroids in vesicles. The cells on the left are uninfected. 5  m Bacteroids within vesicle Nodules Roots

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure Development of a soybean root nodule Rhizobium bacteria Dividing cells in root cortex Bacteroid 1Roots emit chemical signals that attract Rhizobium bacteria. The bacteria then emit signals that stimulate root hairs to elongate and to form an infection thread by an invagination of the plasma membrane. 4The nodule develops vascular tissue that supplies nutrients to the nodule and carries nitrogenous compounds into the vascular cylinder for distribution throughout the plant. 2The bacteria penetrate the cortex within the infection thread. Cells of the cortex and pericycle begin dividing, and vesicles containing the bacteria bud into cortical cells from the branching infection thread. This process results in the formation of bacteroids. 3Growth continues in the affected regions of the cortex and pericycle, and these two masses of dividing cells fuse, forming the nodule. Bacteroid Developing root nodule Dividing cells in pericycle Infection thread Infected root hair Nodule vascular tissue 4

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure Mycorrhizae 1Ectomycorrhizae. The mantle of the fungal mycelium ensheathes the root. Fungal hyphae extend from the mantle into the soil, absorbing water and minerals, especially phosphate. Hyphae also extend into the extracellular spaces of the root cortex, providing extensive surface area for nutrient exchange between the fungus and its host plant. 2Endomycorrhizae. No mantle forms around the root, but microscopic fungal hyphae extend into the root. Within the root cortex, the fungus makes extensive contact with the plant through branching of hyphae that form arbuscules, providing an enormous surface area for nutrient swapping. The hyphae penetrate the cell walls, but not the plasma membranes, of cells within the cortex. Mantle (fungal sheath) Epidermis Cortex Mantle (fungal sheath) Endodermis Fungal hyphae between cortical cells (colorized SEM) 100  m Epidermis Cortex Fungal hyphae Root hair 10  m (LM, stained specimen) Cortical cells Endodermis Vesicle Casparian strip Arbuscules

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure Unusual Nutritional Adaptations in Plants Staghorn fern, an epiphyte EPIPHYTES PARASITIC PLANTS CARNIVOROUS PLANTS Mistletoe, a photosynthetic parasiteDodder, a nonphotosynthetic parasite Host’s phloem Haustoria Indian pipe, a nonphotosynthetic parasite Venus’ flytrap Pitcher plants Sundews Dodder

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sun Dew Trap Prey