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

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)

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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

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Online material: http://www.sfu.ca/bisc/bisc367/

• Course outline

• Lab handouts

• Posted lecture presentations

• Lab project data and info.

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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