Plant growth and development Plant resistance physiology...

«Bioloģija nebiologiem»: plant physiology

Plant growth and development

Plant resistance physiology

Plant movements

Differences of plant and animalorganisms

Movement

Nutrition

Development

Regeneration capacity

Animals Plants


Movement

Nutrition

Development


Animals

+Plants

-


Movement

Nutrition

Development


Animals

+

heterotrophic

Plants

-

autotrophic


Movement

Nutrition

Development


Animals

+

heterotrofs

canalyzed development

Plants

-

autotrofs

plasticdevelopment


Movement

Nutrition

Development


Animals

+

heterotrofs

canalyzed development

low

Plants

-

autotrofs

plasticdevelopment

high

Specific properties of plants

Plastic developmenthigh regeneration capacitylow movement capacity

autotrophic nutrition Photosynthesis

cell totipotence

Metamericstructure

Phenotypicplasticity

Cell totipotence

Totipotent cell — cell that through divisionand differentiation cal regenerate thewhole organism or any of its cell types

Plant cells are totipotent orpluripotent

Non-differentiatedcells can divide

DIFFERENTIATION

Differentiated cells do notdivide, they perform specificfunctions

DEDIFFERENTIATION

REDIFFEREN-TIATION

Cell totipotence

Metamers

leaf

node

internode

bud

phytomer

leaf

node

Axillary bud

Meristems

Vegetative Reproductive

Shoot apical meristem

- active (apex)- inactive (axillary buds)

Meristem — localized embryonic tissues that produce phytomers

Clonal plants

Foto: Ģ. Ieviņš

Clonal plants

Magori et al., 2003

Clonal integration is adaptive in heterogenous habitats,where sharing of resources can be beneficial to the plants(connected clones)

Phenotypic plasticity

Phenotypic plasticity capacity of theorganism to alterphenotype to get acclimatedto the environment

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http://www.geochembio.com/ecology/climate-change/climate-change-on-plants.html


Foto: Ģ. Ieviņš

Alyssum gmelinii, Gmelina alise, dune forest edge


Foto: Ģ. Ieviņš

Alyssum gmelinii, Gmelina alise, white dune


Foto: Ģ. Ieviņš

Alyssum gmelinii, Gmelina alise


Foto: Ģ. Ieviņš

Honckenya peploides, biezlapainā sālsvirza

Plant reaction to the environment

Sub-optimal conditions(physical,chemical factors)

Herbivores,pathogens

Signal perception

Signal recognition andtransduction

Reaction

Plant reaction to the environment

Abiotic stress:Sub-optimal conditions(physical,chemical factors)

Biotic stressHerbivores,pathogenscompetition

Active reactions:Active reactions:Changes in metabolismChanges in metabolismChanges in developmentChanges in developmentprotectionprotection

Active reactions:Active reactions:synthesis of toxinssynthesis of toxinsand other protextiveand other protextivesubstancessubstances

Example: freezing tolerance

When temperature lowers below 0 ºC bulk water in the cells freezes and forms ice crystals

Uncontrolled formation of crystals as a result of rapid decrease of temperature may lead to cell damage

Plant reactions

Cell dehydration,minimizing bulk waterDehydrins protectmacromolecules fromdamage

«controlled» formation of crystals- synthesis of antifreeze proteins(lower temperature of ice formationand altered crystal shape)- ice crystals form in the apoplast

Example: freezing toleranceEffect of antifreeze protein on ice crystal formation in rye

Griffith et al. 1992

Stages of ice crystal formation in antifreezeprotein solution

Ice crystals in acclimatedplants

Ice crystals in non-acclimated plantsIce crystals in distilled water

Example: protection against herbivores

Plants are able to recognizespecific damage caused byherbivores and induce active protectivereactions


Zea mays,kukurūza

Spodoptera exigua

Microplitis croceipes

Linolenic acid

volicitin

volatiles

Turlings et al. 2000


Constitutive protection

Morphological adaptation(mechanic protection)

- reinforced cell walls- cuticule- spines, thorns

Physiological adaptation(chemical protection)

- toxinc(nicotin)- antinutrients(proteinase inhibitors)- repellents

Induced protection

Direct Indirect

volatilesthat attractnaturalenemies ofthe herbivores(parasites etc)

Plant movements

Tropisms

direction of the movementdepends on thedirection of the stimulusthat causes the movement

phototropismgeotropismtigmotropismhydrotropismchemotropism

Nastic movements

direction of the movementis independent of thedirection of the stimulus

nictinastyseismonastyhydronasty

***Nutationautonomous movement caused bygrowth. Elliptic movementof the apex (tip of the plant)

RECEPTOR

Movement is a reaction to stimulus

STIMULUS SIGNAL MOVEMENT

Where and how isthe stimulus percepted?Whan is the nature ofthe receptor?

What is the natureof the signal (orsignal chain)?

What is the mechanismof the movement?

Phototropism: growth reaction to light

STEM:positive phototropism(growth towards light)

ROOT:usually negative phototropism(growth away from light)

Stimulus: light

Perception of stimulus:photoreceptors

Signal transduction: formationof auxin gradient

Signal transduction: exspression of specific genes

Reaction: shadedside grows faster,the plant bends



Change of cell turgor as a mechanismof movement

Tigmotropism: reaction to touch

Plant has tendrils that bind around objects if the touchis percieved from the inner side

Part of the reaction mechanism is volatile growth regulator methyljasmonate

Seismonasty: reaction to touch

Mimosa pudica

Stimulus is percieved by specialized cells sensitiveto touchAn electrical signal is generatedand is translated to other cellsIon permeability of thecell plasma membrane is changed and results in change of turgorCell size ischanged and becauseof that — spatialorientation of the plantorgan

Plant growth and development Plant resistance physiology...

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