Plant Biology Fall 2006 BISC 367 Plant Physiology

Plant Biology Fall 2006 BISC 367 - Plant Physiology Lab Spring 2009

1. 0 Plant Physiology Lab Spring 2009 Professor: Dr. Aine Plant, office B 8228 e-mail: aplant@sfu. ca (preferred) Tel: 778 -782 -4461 Lab Instructor: Doug Wilson, office B 9239 e-mail: dwilson@sfu. ca TA: Lectures: Owen Wally e-mail: owenw@sfu. ca Tuesday at 11: 30 - 12: 20 AQ 4120 Lab & tutorial: Thursday 1: 30 - 5: 20 in B 8241 Thursday 11: 30 to 12: 20 in B 8241 (not in AQ 5049)

1. 1 Mark distribution: each 2 quizzes 2 lab reports 10 % each 17. 5 % Lab report based on project 25 % Lab worksheets 20% Quiz 1: Quiz 2: Tuesday Feb. 10 Project report due: First week of exams Textbook: Taiz and Zeiger “Plant Physiology” 4 th edition On reserve in the library Tuesday Mar. 24

1. 1 Online material: http: //www. sfu. ca/bisc 367/ • • Course outline Lab handouts Posted lecture presentations Lab project data and info.

1. 1 Plant Physiology Lab Spring 2009 Notices: General reading: • Chapter one focus on: • Tissues • Chloroplasts • Plasmodesmata • Chapter 15 covers cell walls. Cover the basics only!

Overview - plant morphology Shoot system • Supports and places leaves • Transports H 2 O and nutrients • Leaves • Photosynthesizers • Reproductive structures Root system • Anchors plant • Absorbs water and minerals • Storage (CHO) & synthesis of some hormones

Overview - plant morphology 3 major tissue systems make up the plant body • Ground tissue • cortex • mesophyll • pith • Vascular tissue • Dermal tissue • Tissue systems are continuous throughout the plant

3 Tissue Systems • Ground tissue includes: • Parenchyma tissue • Collenchyma tissue • Sclerenchyma tissue • Vascular tissue includes • Xylem tissue • Phloem tissue • Dermal tissue • Epidermis

Tissue Systems • Parenchyma tissue: • SIMPLE – Made up of a single cell type • Cells are ALIVE at maturity • Capable of dividing – TOTIPOTENT • Involved in wound regeneration and range of metabolic fxns

Tissue Systems • Chollenchyma tissue: • • SIMPLE Cells are ALIVE at maturity Contain unevenly thickened walls Support young growing stems and organs

Tissue Systems • Sclerenchyma tissue: • • SIMPLE Cells are dead at maturity Typically lack protoplasts Possess secondary walls with lignin – Strong polymer • Support stems and organs that have stopped growing fibres sclereid Economically important tissue! e. g. Hemp fibres

Tissue Systems • Xylem tissue: • COMPLEX – Made up from more than one cell type • Functions – Conduction of H 2 O – Structural support • Cells are elongated & dead at maturity • Lack protoplasts • Possess elaborately thickened secondary walls with lignin (very strong) • 2 main cell types – – Vessel members Tracheids

Tissue Systems – Tracheids (primitive): • Tracheids “stack” longitudinally in the stem overlapping at tapered ends Tracheid 1 Pits Tracheid 2 How does H 2 O pass from one tracheid to the next? • Passes through aligned pits of neighbouring tracheids • Pit membrane consists of 1 o wall only

Tissue Systems – Vessel members (advanced): • Stack end to form a vessel (long) • Perforation plate at ea. end of a member permits easy water flow 3 vessel members stacked end to form part of a vessel Slotted perforation plate forms end wall of a vessel member Water passes from vessel to vessel via pits

Tissue Systems • Xylem is a complex tissue: – Also present • Parenchyma tissue (nutrient storage) • Fibres/sclereids

Tissue Systems • Phloem tissue – Complex – Functions • Conduction of nutrients – Cells are alive at maturity but highly modified • Lack: – Nucleus – Definition between cytoplasm and vacuole – 2 main cell types • Sieve cells • Sieve tube members

Tissue Systems – Sieve tube members (advanced) • Elongated cells • Sieve tube members stack end to form a sieve tube • End walls form sieve plates and contain pores that connect the cytoplasm of two sieve cells for solute transfer Sieve tube member 1 Sieve plate Sieve tube member 2

Tissue Systems – Sieve tube members and sieve cells are connected to specialized cells A sieve tube member is always associated with a companion cell • Connected via plasmodesmata • companion cell provides: • metabolic functions • Loads sugars for transport

Tissue Systems • Dermal tissue – Functions • Mechanical protection – Made up of epidermal (parenchymal) cells • Cells overlaid with a waxy cuticle to minimize H 2 O loss Waxy cuticle

Tissue Systems Dermal tissue – Also present • Guard cells – Regulate size of the stomatal pore and • Movement CO 2 into leaf • Movement H 2 O vapour out Stomatal pore

Tissue Systems Dermal tissue – Also present • Trichomes aka “hairs” – – Increase reflectance of solar radiation Absorb H 2 O and minerals (epiphytes) Contain chemical defenses Can impale larvae of some insects Branched & glandular trichomes

Root anatomy • Root structure – Simple – Epidermis (outer layer of cells) • Protects root • Plays important role in water uptake – Facilitated by root hairs – Tubular extension from epidermal cell • Increases surface area for water uptake – Produced in zone of maturation • Short lived Root epidermal cell with root hair

Root anatomy – Cortex • Ground tissue that occupies most volume of root • Cells often adapted for storage – Starch • Numerous air spaces exist – Roots need to respire! • Innermost boundary of cortex is the endodermis

Root anatomy – Vasculature in a eudicot root • Protostele – – Vascular tissue occupies the centre of root Xylem arranged as a “star” Phloem tissue is located between the arms of the xylem “star” Pericycle tissue surrounds vascular tissue

Root anatomy – Vasculature in some monocot roots develops with a central pith Central pith Maize root

Stem anatomy • Primary structure of a eudicot stem – 1 o vascular tissue are present as a cylinder of strands separated by ground tissue • Interfascicular rays or pith rays – 1 o phloem is present at the outside of the bundle – 1 o xylem is present on the inside of the bundle – Ground tissue in centre of stem is the pith – Ground tissue that lies outside the vascular bundle is the cortex – Outermost layer is the epidermis • Contains stomata and trichomes

Stem anatomy • Primary structure of a eudicot stem – Single layer of cells between 1 o phloem & 1 o xylem remain meristematic • Become vascular cambium – Cylindrical meristem that is responsible for 2 o growth • Remainder of cambium arises from interfascicular parenchyma – Note, not all eudicots undergo 2 o growth • No cambium arises

Anatomy of a woody stem – Woody stem during first year of growth

Leaves • Evolved to photosynthesize – Divided into • Blade or lamina • Petiole or stalk – Leaf anatomy is influenced by the amount of available water: • Plants can be grouped according to their water requirements: • mesophyte – Plant with plentiful water supply • hydrophyte – Grows partially or completely submerged • xerophyte – Adapated to dry environment

Leaf anatomy • General features of mesophytic leaves (eudicot) – Stomata more numerous on lower surface • sheltered – Photosynthetic tissue (mesophyll) is differentiated into: • Upper palisade parenchyma – Upright cells with many cps • Lower spongy mesophyll – Permeated by air spaces – Vasculature is netted venation • Xylem towards upper surface • Phloem towards lower surface • Small veins collect P/S products – Surrounded by a bundle sheath – Controls entry/exit of material • Large veins transport P/S products from leaf

Leaf anatomy – Anatomical modifications in hydrophytes • Problem = obtaining enough CO 2 & O 2 – Stomates not present or in upper epidermis (floating leaf) – Thin cuticle – Large amounts of air in spongy mesophyll • Gas exchange • buoyancy – Reduced vascular tissue • Partic. xylem – Reduced amount of support tissue

Leaf anatomy Modifications present in xerophytes • Problem = getting enough water – Many of these plants have reduced leaf size or no leaves – Large number of stomates • Optimize gas exchange when water is plentiful? • Remember stomates usually shut – Stomates generally sunk in depression in leaf surface • Assoc. with trichomes • Both increase depth of boundary layer & slow rate of water loss – Thick cuticle – Multiple epidermis • Modified to store water – More supporting tissue to compensate for reduced turgor Stomate

Leaf anatomy – General features of monocot leaves • Parallel venation system • Lack a defined palisade/spongy mesophyll layers – Leaves tend to be vertically oriented • Anatomy modified according to mode of P/S – C 4 photosynthesis • Carbon fixed to form a C 4 acid in mesophyll cell • C 4 acid is transported to bundle sheath cell & decarboxylated • Released CO 2 is refixed by C 3 P/S CO 2 + C 3 acid C 4 acid Mesophyll cell Bundle sheath cell

Leaf anatomy – Leaves of C 4 plants display Kranz anatomy • Mesophyll and BSC form 2 concentric layers around a vascular bundle • Bundle sheaths are close together C 4 leaf – Leaves of C 3 plants have well separated bundle sheaths and do not have Kranz anatomy C 3 leaf