00445 - Plant Physiology

Learning outcomes

At the end of the course, including also an intensive lab, the student assimilates with critical insight and in depth analysis, the main themes of plant physiology at the molecular level (transport, photosynthesis, metabolism, mineral nutrition, hormonal regulation and photomorphogenesis).

Course contents

Lectures (5 CFU) - Prof. Paolo Trost 

Membrane transport, cell water relationships and mineral nutrition. Proton pumps of the plant cell. The H+-ATPase of the plasma membrane: structure, mechanism of action, regulation. Membrane potential and electrochemical potential. Aquaporins. Water transport at the cellular level: hydrostatic pressure (P) and osmotic pressure (π). Water (Ψw), pressure (Ψp) and osmotic (Ψs) potentials. Stomata movements and variation of Ψs. Cell expansion and variations of Ψp. Essential nutrients. Mineral nutrition in agriculture. Mycorrhizae. Strategies for iron absorption.

Water relations in the whole plant. Soil-plant-atmosphere continuum. Water potential in the soil, root uptake and ΔΨw. Root pressure and guttation. Movement of the xylem sap and ΔΨp. Transpiration and Δ CWV. Cavitation.

Photosynthesis (light phase). Light. Chloroplasts. Photosynthetic pigments: excitation and de-excitation. Photosystems. Structure and function of photosystem II. Cytochrome b6f and Q cycle. Structure and function of photosystem I. ATPsynthase of chloroplasts. Scheme Z. Non-cyclic (linear). Stoichiometric ratios of absorbed photons, oxygen evolved, protons accumulated in the lumen, NADPH and ATP produced.

Photosynthesis (metabolism). Carbon metabolism. Rubisco: structure, reactions, regulation. Calvin cycle and its light/dark regulation. Thioredoxins. Photorespiration. Gross and net photosynthesis. Compensation point for CO2 and internal concentration of CO2. Mechanisms of concentration of CO2. C4 plants: general metabolic scheme, anatomic features and differentiation of chloroplasts. CO2 compensation point in C4 plants. Net photosynthesis as a function the temperature in C3 and C4 plants. Water use efficiency. CAM plants. Metabolic relationships between starch and sucrose. Biosynthesis of sucrose, amylose and amylopectin. Architecture of starch granules. Sink-source relationships. Phloem: anatomy and cytology. Phloem loading: apoplastic and symplastic. Phloem transport. 

Assimilation of nitrogen. Absorption and reduction of nitrate to ammonium. Ammonium assimilation. Aromatic amino acid biosynthesis: glyphosate and transgenic plants.

Repiration. Functions of respiration in plants. Conversion of sucrose into hexoses. Plastid and cytosolic glycolysis. Pentose phosphate pathway and differencial regulation between cytoplasm and chloroplast. Krebs cycle. Respiratory chain: internal and external NAD(P)H dehydrogenases, alternative oxidase. 
Photomorphogenesis. Scoto- and photo-morphogenesis. Classes of plant photoreceptors. Phytochrome: molecular structure, photoconversion, absorption spectrum, photostationary state, action spectrum. Nuclear translocation of Pfr and modification of gene expression. Shade avoidance response. Cryptochromes CRY. De-etiolation and hypocotyl elongation inhibition: the role of CRY1 and PHY.    

Phyto-hormones: auxin. General concepts. Auxins, natural and synthetic. IAA biosynthesis and conjugation. Polar auxin transport and transport in the phloem. Role of IAA role in cell expansion. IAA and phototropism. IAA and positive gravitropism of the root. Regulation  of gene expression mediated by IAA. 
Laboratory (1 credit) - Dr. Francesca Sparla
Purification of chloroplasts from spinach leaves. Extraction of photosynthetic pigments. Spectrophotometric determination of chlorophyll a and b. Measurement of an enzyme activity of chloroplasts. Determination of protein content (Bradford). Cloroplastic proteins separation by gel electrophoresis.

Readings/Bibliography

Rascio N, Carfagna S, Esposito S, La Rocca N, Lo Gullo MA, Trost P, Vona V (2012) Elementi di Fisiologia vegetale. EdiSES

Teaching methods

The theoretical part of the course (5 credits) will consists in lectures with projection of pictures and diagrams (power point). Questions are always welcome, both during and after the lectures. The lab part of the course will include a brief introductory lecture to explain the experimental protocol that all students will be asked to   follow individually. Students will be divided into groups and each group will be supervised by a teacher or tutor. At the end of the workshop, a comparative analysis of the data individually collected by students will be performed.

Assessment methods

The exam consists of a written test and an oral examination. Only students who have passed the threshold of sufficiency in the written test are admitted at the oral examination.

Teaching tools

The course will take place in classrooms with PC projection. All lectures will be given with power point presentations. The files of power point presentations will be made ​​available to students at the end of the course (downloadable files from AMSCAMPUS). The lab course will take place in a didactic laboratory with single workstations, equipped with centrifuges, spectrophotometers and electrophoretic cells.

Office hours

See the website of Paolo Bernardo Trost