Part 2!! I know, I know… you can hardly contain the excitement  Plant Physiology Part 2!! I know, I know… you can hardly contain the excitement 

Plant response mechanisms Plants are stationary and so must respond to environmental stimuli by making internal adjustments which makes their sensory systems even more intricately related and incredibly sensitive. Hormone = plant growth regulator (compounds that modify or control one or more specific processes within a plant) Many major classes of hormones that have a wide range of functions

Plant hormones Plant movement Auxins: substances that promote stem elongation, lateral root development, regulates development of fruit. Found in shoot tips and transported (unidirectional) at a rate of 1cm/hr **Artificial uses include: herbicides (especially turf) to eliminate weeds, sprayed on greenhouse grown tomatoes induces normal fruit development Cytokinins: produced in roots and transported to other organs and stimulate cytokinesis (growth and development of tissue cells). Move through xylem sap and must be paired with auxins to actually work. Also show anti- aging results and slow the progress of apoptosis (automatic cell death) Plant movement

Plant Hormones Gibberellins are produced in the meristems of the apical buds and roots as well as developing seeds and young leaves. They stimulate stem elongation, pollen development, fruit growth, seed germination and development. Both auxins and gibberellins need to be present for fruit to develop. Used commercially sprayed on seedless grapes to increase size of the fruit. When water reaches the seed, gibberellins are released and signal germination

Plant Hormones Brassinosteroids are found in all plant tissue and help with cell expansion and cell division in the shoots. Abscisic acid (ABA) SLOWS growth which is what primarily controls seed dormancy. There are certain conditions that need to be met to actually move from dormant stages to germinating stages. When there are drought conditions, ABA helps signal to stomata to close Strigolactones move up from the roots and help promote seed germination as well as helping roots form symbiotic relationships with fungi (mycorrhizae) Ethylene gas can be produced in most parts of the plant and is especially prominent if the plant has been wounded or stressed. It promotes the ripening of fruit and leaf abscission, flowering, and root hair formation.

Your task today Research ways that plants respond to stimuli such as bacterial or viral infections, drought, flooding, high salt and heat conditions, extreme cold and attacks by herbivores Remember to incorporate some of the things we’ve mentioned in class today

The role of plants in ecosystems You need to research and record information about ONE of the topics from each section listed below: Section Symbiotic relationships Human/plant interactions Possible topics Parasitic Commensalism Mutualism Predatory Slash and burn Artificial selection Exotics/Noxious weeds Monocropping