paul.m.hasegawa.1@purdue.edu Mineral Nutrition Plant life cycle #11- Plant Mineral Nutrition HORT 301 – Plant Physiology September 20, 2010 Taiz and Zeiger – Chapter 5, Chapter 12 paul.m.hasegawa.1@purdue.edu Skotomorphogenesis Seed germination Hormones, signaling, genetic determinants Embryo and Seed development Plant life cycle Photomorphogenesis Photoreceptors Phytochrome Structure and function of cells Phytochrome: regulation of light responses Photosynthesis: light reaction Photosynthesis: carbon fixation Photorespiration Primary & secondary metabolism Respiration Mineral Nutrition Water

Plant Mineral Nutrition HORT 301 – Plant Physiology September 20, 2010 Taiz and Zeiger - Chapters 5 & 12 paul.m.hasegawa.1@purdue.edu Plant mineral nutrition – essential elemental nutrients required by plants courtesy of Burkhard Schulz

-K -Mg -Fe -N -Ca Essential mineral elements Growth, development or completion of life cycle Metabolism and plant structure -K -Mg -Fe -N -Ca

Essential macronutrients and micronutrients Macronutrient – up to 1.5%, 15,000 ppm in dry matter

Micronutrient - 100 ppm (dry matter) or less

Mineral nutrient classification based on biochemical function Group 1 (N and S) – components of organic molecules Group 2 (P, Si, B) – P- energy storage (ATP) or Si & B - cell wall structure

Group 3 (K, Ca, Mg, Cl, Mn, Na) – metabolism, enzyme co-factors, osmotic adjustment, signaling, structure

Group 4 (Fe, Zn, Cu, Ni, Mo) – metals involved in redox reactions (electron transfer)

Hydroponic culture – mineral nutrients, aeration, pH control

Mineral nutrient forms in soils and cells K+ Ca2+ Cl- P – H2PO4- S – SO42- N – NH4+ or NO3-

Mineral nutrient deficiency – Web Topic 5 Mineral nutrient deficiency – Web Topic 5.1 for typical deficiency symptoms – N, P, K, Ca Epstein & Bloom Mineral Nutrition of Plants 2004

Mobile and immobile mineral elements and symptom development Mobile - symptoms evident first in older leaves Non-mobile – symptoms develop first in new leaves

Tissue mineral nutrient content – growth and yield Critical concentration – minimum nutrient limited Adequate zone – maximal growth and yield Toxic zone – nutrient excess

Plant nutrition and soil pH – pH 7 Plant nutrition and soil pH – pH 7.0 is typically optimal for nutrient solubility and availability

Mineral nutrients in soils – weathering of soils and organic materials are sources Soil properties affects availability in the soil solution for root absorption

Mineral nutrient absorption roots absorb mineral nutrients Water and nutrient deprivation causes remodeling of root architecture to maximize root surface area (secondary roots and root hairs) Hydrotropism – root capacity to sense water and grow toward the source

+ - portion of root system receiving complete nutrient solution Localized supply of PO4,2- , NO3- , NH4+ , or K+ and the architecture of barley root growth + - portion of root system receiving complete nutrient solution - - Part of the root system receiving the solution deficient in specified nutrient Drew (1975) New Phytol. 75 : 461-478

Primary root structure and nutrient absorption – uptake may occur all along the root Root hairs increase surface

Nutrient absorption by roots creates a depletion zone Root or root hair growth increases access to soil solution that is not depleted of nutrients

Mycorrhiza (mycorrhizae) – root interaction – nutrient and water absorption Mycorrhizal fungi - sugars, plants – mineral, nutrients and water Ectomorphic mycorrhizal fungi – hyphae extend along apoplast of cortical cells Arbuscular mycorrhizal fungi – hyphae penetrate into cortical cell symplast and branch (arbuscule)

Radial ion movement to the xylem Transport to shoots in the transpiration stream

Xylem loading – transport from endodermal cells to xylem elements via xylem parenchyma cells Transport proteins regulate ion transport into and out of the xylem Ion movement from root to shoot in the transpiration stream

Mineral nutrient assimilation – incorporation into organic molecules NH4+ or NO3-, SO42-, and H2PO42- Sulfur – SO42- is a product of soil weathering Uptake into roots via SO42- - H+ symporter and translocated through the plant SO42- - assimilated into cysteine

Phosphorous – HPO42- - uptake (PO42- -H+ symporter) and translocated form Assimilated into ATP (ATP synthase), photosynthesis, oxidative phosphorylation (respiration) Cation mineral nutrients (K, Ca, Mg, Fe, Mn, Cu, Co, Na, Zn) – function as ions or are in organic molecules via noncovalent bonds Coordination bonds (several oxygen or nitrogen atoms share electrons) to form a bond with a cation nutrient, chlorophyll a

Electrostatic interactions – charge group attraction, e. g Electrostatic interactions – charge group attraction, e.g., Ca2+ for carboxylate groups in pectin (Ca2+-pectate)