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Plant Biology Fall 2006
BISC 367 - Plant Physiology LabSpring 2009
Plant Physiology LabSpring 2009
Professor: Dr. Aine Plant, office B8228
e-mail: [email protected] (preferred) Tel: 778-782-4461
Lab Instructor: Doug Wilson, office B9239
e-mail: [email protected]
TA: Owen Wally
e-mail: [email protected]
Lectures: Tuesday at 11:30 - 12:20
AQ 4120
Lab & tutorial: Thursday 1:30 - 5:20 in B8241
Thursday 11:30 to 12:20 in B8241 (not in AQ5049)
1.0
Mark distribution: 2 quizzes 10 % each
2 lab reports 17.5 % each
Lab report based on project 25 %
Lab worksheets 20%
Quiz 1: Tuesday Feb. 10
Quiz 2: Tuesday Mar. 24
Project report due: First week of exams
Textbook: Taiz and Zeiger “Plant Physiology” 4th edition
On reserve in the library
1.1
Online material: http://www.sfu.ca/bisc/bisc367/
• Course outline
• Lab handouts
• Posted lecture presentations
• Lab project data and info.
1.1
1.1
Plant Physiology LabSpring 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• Stem
• Supports and places leaves• Transports H2O 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 H2O
– 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
Tracheid 2
Pits
How does H2O pass from one tracheid to the next?• Passes through aligned pits of neighbouring tracheids• Pit membrane consists of 1o wall only
Tissue Systems
– Vessel members (advanced): • Stack end to end to form a vessel (long)
• Perforation plate at ea. end of a member permits easy water flow
Slotted perforation plate forms end wall of a vessel member Water passes from vessel to vessel via pits
3 vessel members stacked end to end to form part of a vessel
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 end to form a sieve tube• End walls form sieve plates and contain pores that connect the the
cytoplasm of two sieve cells for solute transfer
Sieve tube member 1
Sieve tube member 2
Sieve plate
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 H2O loss
Waxy cuticle
Tissue SystemsDermal tissue
– Also present• Guard cells
– Regulate size of the stomatal pore and• Movement CO2 into leaf• Movement H2O vapour out
Stomatal pore
Tissue SystemsDermal tissue
– Also present• Trichomes aka “hairs”
– Increase reflectance of solar radiation– Absorb H2O 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
– 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
Root anatomy
• Primary structure of a eudicot stem– 1o vascular tissue are present as a
cylinder of strands separated by ground tissue
• Interfascicular rays or pith rays
– 1o phloem is present at the outside of the bundle
– 1o 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 1o
phloem & 1o xylem remain meristematic
• Become vascular cambium– Cylindrical meristem that is
responsible for 2o growth
• Remainder of cambium arises from interfascicular parenchyma
– Note, not all eudicots undergo 2o growth
• No cambium arises
Stem anatomy
– Woody stem during first year of growth
Anatomy of a woody stem
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
– Anatomical modifications in hydrophytes
• Problem = obtaining enough CO2 & O2
– 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
– C4 photosynthesis• Carbon fixed to form a C4 acid in mesophyll cell• C4 acid is transported to bundle sheath cell & decarboxylated• Released CO2 is refixed by C3 P/S
CO2 + C3 acid
C4 acid C4 acid
CO2 + C3 acid
P/S
Mesophyll cell Bundle sheath cell
Leaf anatomy
– Leaves of C4 plants display Kranz anatomy
• Mesophyll and BSC form 2 concentric layers around a vascular bundle
• Bundle sheaths are close together
– Leaves of C3 plants have well separated bundle sheaths and do not have Kranz anatomy
C4 leaf
C3 leaf
Leaf anatomy