Lecture Plant physiology

PLANT PHYSIOLOGY Faculty of Biology Hanoi University of Sciences – VNU 2014 Dr Lê Quỳnh Mai E-mail: lequynhmai80@gmail.com What is Plant Physiology? Plant physiology is a study of the plant way of life, which includes various aspects of the plant lifestyle and survival including: metabolism, water relations, mineral nutrition, photosynthesis, respiration, growth, development, regulation, movement, irritability (response to the environment) Helpful Study Materials Arabidopsis thaliana The drosophila of Plant Kingdom Why? It has many advantages such as … Plant Growth and Development Main Contents William G Hopkins The regulation of development Major stages during the life cycle Defense against biotic enemies Responding to environmental factors p.453-492 p.369-424 Main References Three Terms = Changes (increase) in size and mass Differentiation = Changes in characteristics and functions Development = Growth + All of the changes in life cycle Plant Cell Development Cell division Growth Cell enlargement Cell differentiation Differentiation Cell division CYTOKININ can induce cell division What? For what? Create new cells Increase number of cells Where? Take place in Meristem ABA When? Always Cell enlargement What? Cells “grow up” Increase the size, volume with the For what? changes in shape and content of cell Where? When? In enlongation zone Always Cell wall extensibility XET: Xyloglucan EndoTransglycosylase Cell differentiation - Changes in structure - Changes for different functions To become A or B? … Why? Totipotent differentiation A B E.g Plant growth regulators Messages Cell B Cell A Hormones Adjustment activities A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism In essence, it is a chemical messenger that transports a signal from one cell to another All multicellular organisms produce hormones; plant hormones are called phytohormones How phytohormones differ from animal ones? Comparison Animal hormones Plant hormones Peptides/proteins/small organic Small organic molecules molecules Synthesised in specialised glands Synthesised throughout the plant Affect distant targets (often transported in the circulatory system) Affect local cells and tissues, or can be transported through the vascular system Specialised effects Wide-ranging effects Regulated by the central nervous system `Decentralised' regulation Main groups of phytohormones Hormone Function Location Auxins stem elongation apical dominanace root formation produced in shoot apical meristem Cytokinins cell division differentiation produced in roots Gibberellins stem & intemode elongation seed germination produced in apical portion of root & shoot abscission fruit ripening produced in leaves, stems & young fruits suppression of bud growth stomatal closing leaf senescence mature leaves, fruits & root caps cell enlongation, cell expansion promotion of vascular differentiation growth promoting by stem enlongation pollen tube formation, enlongation … Wide range of plant organs (short distance activity) Ethylene Abscisic Acid Brassinosteroid Transport of phytohormones Auxin Gibberellin Ethylen Auxin Auxin Ethylen ABA Auxin ABA Gibberellin Cytokinin Gibberellin Cytokinin ABA Ethylen Phytohormone interaction Genetical regulation interaction Plant hormones in stress responses Signal Reception Transduction Response Mechanism of transduction Light sensistive systems Light Phototropins Cryptochromes Signal Perceiving Locations Recall……… What should be studied in part of plant development? Regulation of development Stages in life cycle Rely on and Cope with conditions How are the cells development? Born from other divisions Grow up step by step Make their own characteristics What are phytohormones? Definition Classification Interaction Why are these molecules but not others? Selection process = Selecting the most suitable molecule growth promoting signal molecules stress signal molecules Osmotic stress Chemical stress UV-oxidative stress Mechanical stress