35 lecture presentation r

7/24/2019 35 Lecture Presentation R

1/77

LECTURE PRESENTATIONS

For CAMPBELL BIOLOGY, NINTH EDITIONJane B. Reece, Lisa A. Urry, Micae! L. Cain, "#e$en A. %asser&an, Pe#er '. Minors(y, Ro)er# B. Jac(son

* +-- Pearson E/ca#ion, Inc.

Lectures by

Erin Barley

Kathleen Fitzpatric

Plant Structure! "r#$th! an%

&e'el#p(ent

Chapter )*


2/77

The Three Basic Plant Or+ans, R##ts!

Ste(s! an% Lea'es Basic morphology of vascular plants reflects their

evolution as organisms that draw nutrients from

below ground and above ground Plants take up water and minerals from below

ground

Plants take up CO2and light from above ground



3/77

Three basic organs evolved: roots, stems, andleaves

They are organied into a root system and a

shoot system



4/77

!igure "#$2Reproductive shoot (flower)

Apical bud

Node

Internode

Apical bud

Vegetative shoot

LeafBladeetiole

!tem

"aproot

Lateral (branch)roots

!hootsystem

Rootsystem

A#illary bud


5/77

%oots rely on sugar produced byphotosynthesis in the shoot system, and shoots

rely on water and minerals absorbed by the root

system

&onocots and eudicots are the two ma'or

groups of angiosperms



6/77

Roots

( root is an organ with important functions:)(nchoring the plant

)(bsorbing minerals and water

) *toring carbohydrates) +n most plants, absorption of water and minerals

occurs near the root hairs, where vast numbers of

tiny root hairs increase the surface area



7/77

!igure "#$"


8/77

&any plants have root adaptations withspecialied functions



9/77

!igure "#$

rop roots

!torageroots

$!trangling%aerial roots

Buttressroots

neumatophores


10/77

Stems

( stemis an organ consisting of)(n alternating system of nodes, the points at

which leaves are attached

) Internodes, the stem segments between nodes



11/77

(n a#illary bud is a structure that has thepotential to form a lateral shoot, or branch

(n apical bud, or terminal bud, is located near the

shoot tip and causes elongation of a young shoot



12/77

&any plants have modified stems -e$g$, rhiomes,bulbs, stolons, tubers.



13/77

!igure "#$#Rhi&omes

Rhi&ome

Bulbs

!torage leaves

!tem

!tolons

"ubers

Root

!tolon


14/77

Leaves

The leaf is the main photosynthetic organ of mostvascular plants

/eaves generally consist of a flattened blade and

a stalk called the petiole, which 'oins the leaf to a

node of the stem



15/77

&onocots and eudicots differ in the arrangementof veins, the vascular tissue of leaves

) &ost monocots have parallel veins

)&ost eudicots have branching veins

+n classifying angiosperms, ta0onomists may use

leaf morphology as a criterion



16/77

!igure "#$1

!imple leaf

A#illary

bud etiole

'ompound leaf

Leaflet

A#illary

bud etiole

oubly

compound leaf

A#illary

bud

etiole

Leaflet


17/77

!igure "#$"endrils

!pines

!torageleaves

Reproductiveleaves

Bracts


18/77

&er(al! -ascular! an% "r#un% Tissues

3ach plant organ has dermal, vascular, andground tissues

3ach of these three categories forms a tissue

system

3ach tissue system is continuous throughout the

plant


!i "# 4


19/77

!igure "#$4

ermaltissue

round

tissue

Vascular

tissue


20/77

+n nonwoody plants, the dermal tissue systemconsists of the epidermis

( wa0y coating called the cuticle helps prevent

water loss from the epidermis

+n woody plants, protective tissues called

periderm replace the epidermis in older regions of

stems and roots

Trichomes are outgrowths of the shoot epidermisand can help with insect defense


!i "# 5


21/77

!igure "#$5

Very hairy pod

(*+ trichomes,mm-)

!lightly hairy pod

(- trichomes,mm-)

Bald pod

(no trichomes)

Very hairy pod.*+/ damage

!lightly hairy pod.-0/ damage

Bald pod.1+/ damage

232RI42N"

R2!5L"!


22/77

The vascular tissue system carries out long6distance transport of materials between roots andshoots

The two vascular tissues are 0ylem and phloem

3ylem conveys water and dissolved mineralsupward from roots into the shoots

hloem transports organic nutrients from where

they are made to where they are needed



23/77

Tissues that are neither dermal nor vascular arethe ground tissue system

7round tissue internal to the vascular tissue is

pith8 ground tissue e0ternal to the vascular tissue

is corte#

7round tissue includes cells specialied for

storage, photosynthesis, and support



24/77

C#((#n Types #. Plant Cells

/ike any multicellular organism, a plant ischaracteried by cellular differentiation, the

specialiation of cells in structure and function



25/77

The ma'or types of plant cells are:) Parenchyma

) Collenchyma

) *clerenchyma) 9ater6conducting cells of the 0ylem

) *ugar6conducting cells of the phloem



26/77

arenchyma 'ells &ature parenchyma cells

ave thin and fle0ible primary walls

/ack secondary walls(re the least specialied

Perform the most metabolic functions

%etain the ability to divide and differentiate


Biofli0: Tour of a Plant Cell

!igure "# ;


27/77

!igure "#$;


28/77

'ollenchyma 'ells 'ollenchyma cellsare grouped in strands and

help support young parts of the plant shoot

They have thicker and uneven cell walls They lack secondary walls

These cells provide fle0ible support without

restraining growth


!igure "#$;


29/77

!igure "#$;


30/77

!clerenchyma 'ells !clerenchyma cellsare rigid because of thick

secondary walls strengthened with lignin

They are dead at functional maturity There are two types:

) !clereids are short and irregular in shape and

have thick lignified secondary walls) 8ibers are long and slender and arranged in

threads


!igure "#$;


31/77

g

'ell wall

!clereid cells in pear (L4)

8iber cells (cross section from ash tree) (L4)

-0 m

0 m


32/77

9ater:'onducting 'ells of the 3ylem The two types of water6conducting cells,

tracheids and vessel elements, are dead at

maturity

Tracheids are found in the 0ylem of all vascular

plants



33/77

=essel elements are common to mostangiosperms and a few gymnosperms

=essel elements align end to end to form long

micropipes called vessels


!igure "#$;


34/77

gVessel "racheids *++ m

"racheids and vessels(colori&ed !24)

erforation

plate

Vesselelement

Vessel elements6 withperforated end walls

its

"racheids


35/77

!ugar:'onducting 'ells of the hloem !ieve:tube elements are alive at functional

maturity, though they lack organelles

!ieve plates are the porous end walls that allowfluid to flow between cells along the sieve tube

3ach sieve6tube element has a companion cell

whose nucleus and ribosomes serve both cells


!igure "#$;


36/77

!ieve:tube element (left)and companion cell.cross section ("24)

!ieve:tube elements.

longitudinal view

!ieve plate

; m

'ompanioncells

!ieve:tubeelements

lasmodesma

!ieveplate

Nucleus ofcompanioncell

!ieve:tube elements.longitudinal view (L4)

;+ m

*0 m

!ieve plate with pores (L4)


37/77

C#ncept )*/0, 1eriste(s +enerate cells .#r

pri(ary an% sec#n%ary +r#$th ( plant can grow throughout its life8 this is called

indeterminate growth

*ome plant organs cease to grow at a certain sie8this is called determinate growth



38/77

4eristems are perpetually embryonic tissue andallow for indeterminate growth

Apical meristems are located at the tips of roots

and shoots and at the a0illary buds of shoots

(pical meristems elongate shoots and roots, a

process called primary growth



39/77

Lateral meristems add thickness to woody plants,a process called secondary growth

There are two lateral meristems: the vascular

cambium and the cork cambium

The vascular cambium adds layers of vascular

tissue called secondary 0ylem -wood. and

secondary phloem

The cor< cambium replaces the epidermis withperiderm, which is thicker and tougher


!igure "#$;;


40/77

!hoot tip (shootapical meristemand young leaves)

A#illary budmeristem

Root apicalmeristems

Vascular cambium

'or@( via genetically altered bacteria

*tudying the genes and biochemical pathways

of Arabidopsiswill provide insights into plant

development, a ma'or goal of systems biology



53/77

"r#$th, Cell &i'isi#n an% Cell E2pansi#n

By increasing cell number, cell division inmeristems increases the potential for growth

Cell e0pansion accounts for the actual increase in

plant sie



54/77

The Plane and Symmetry of Cell Division

@ew cell walls form in a plane -direction.perpendicular to the main a0is of cell e0pansion

The plane in which a cell divides is determined

during late interphase

&icrotubules become concentrated into a ring

called the preprophase band that predicts the

future plane of cell division


!igure "#$2#


55/77

reprophase band

m


56/77

/eaf growth results from a combination oftransverse and longitudinal cell divisions

+t was previously thought that the plane of cell

division determines leaf form

( mutation in the tangled-1gene that affects

longitudinal divisions does not affect leaf shape


!igure "#$21


57/77

Leaf epidermal cells ofwild:type mai&e

Leaf epidermal cells oftangled-1mai&e mutant

;+

m


58/77

The symmetry of cell division, the distribution ofcytoplasm between daughter cells, determines cell

fate

(symmetrical cell division signals a key event in

development

) !or e0ample, the formation of guard cells involves

asymmetrical cell division and a change in the

plane of cell division


!igure "#$2


59/77

5nspeciali&edepidermal cell

Asymmetricalcell division

uard cell$mother cell%

evelopingguard cells


60/77

olarityis the condition of having structural orchemical differences at opposite ends of an

organism

) !or e0ample, plants have a root end and a shoot

end

(symmetrical cell divisions play a role in

establishing polarity



61/77

The first division of a plant ygote is normallyasymmetrical and initiates polariation into the

shoot and root

The gnommutant of Arabidopsisresults from a

symmetrical first division


!igure "#$24


62/77


63/77

Orientation of Cell Expansion

Plant cells grow rapidly and Acheaply by intakeand storage of water in vacuoles

Plant cells e0pand primarily along the plants main

a0is

Cellulose microfibrils in the cell wall restrict the

direction of cell elongation


!igure "#$25

'ellulose


64/77

'ellulosemicrofibrils

Nucleus

2longation

Vacuoles

0 m


65/77

1#rph#+enesis an% Pattern F#r(ati#n

attern formation is the development of specificstructures in specific locations

Two types of hypotheses e0plain the fate of plantcells

) /ineage6based mechanisms propose that cell fateis determined early in development and passedon to daughter cells

) Position6based mechanisms propose that cell fate

is determined by final position



66/77

30periments suggest that plant cell fate isestablished late in development and depends on

cell position

+n contrast, cell fate in animals is largely lineage6

dependent


!igure "#$"


67/77


68/77

"ene E2pressi#n an% C#ntr#l #. Cell

&i..erentiati#n

Cells of a developing organism synthesie

different proteins and diverge in structure and

function even though they have a common

genome

Cellular differentiation depends on gene

e0pression, but is determined by position

Positional information is communicated throughcell interactions



69/77

7ene activation or inactivation depends on cell6to6cell communication

) !or e0ample, Arabidopsisroot epidermis forms

root hairs or hairless cells depending on the

number of cortical cells it is touching


!igure "#$";


70/77

'orticalcells

-+

m

GLABRA-2is e#pressed6 andthe cell remains hairless

"he root cap cells will be sloughed offbefore root hairs emerge

GLABRA-2is

not e#pressed6and the cellwill developa root hair


71/77

Shi.ts in &e'el#p(ent, Phase Chan+es

Plants pass through developmental phases, calledphase changes, developing from a 'uvenile phase

to an adult phase

Phase changes occur within the shoot apical

meristem

The most obvious morphological changes typically

occur in leaf sie and shape


!igure "#$"2


72/77

Leaves producedby adult phaseof apical meristem

Leaves producedby Cuvenile phaseof apical meristem


73/77

"enetic C#ntr#l #. Fl#$erin+

!lower formation involves a phase change fromvegetative growth to reproductive growth

+t is triggered by a combination of environmental

cues and internal signals

Transition from vegetative growth to flowering is

associated with the switching on of floral

meristem identity genes



74/77

+n a developing flower, the order of eachprimordiums emergence determines its fate:

sepal, petal, stamen, or carpel

Plant biologists have identified several organ

identity genes-plant homeotic genes. thatregulate the development of floral pattern

These are MADS-boxgenes

( mutation in a plant organ identity gene cancause abnormal floral development


!igure "#$""


75/77

(a) NormalArabidopsisflower

AbnormalArabidopsis

flower

(b)

'a

e

!t

!e

!e

!e

e

e

e


76/77

%esearchers have identified three classes of floralorgan identity genes

The AB' hypothesis of flower formation identifies

how floral organ identity genes direct the formation

of the four types of floral organs

(n understanding of mutants of the organ identity

genes depicts how this model accounts for floral

phenotypes


!epals

etals

!igure "#$"


77/77

!tamens

'arpelsA

B'

A schematic diagram of the AB'hypothesis

(a)

'arpel

etal

!tamen

!epal

A Bgene

activity

B Cgene

activity

C geneactivity

A geneactivity

Activegenes.

9horls.

!tamen

'arpeletal

!epal

9ild type 4utant lac

35 lecture presentation r

Documents