Plant Physiology

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Plant Physiology

• by Lincoln Taiz and Eduardo Zeiger

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WHAT IS PHYSIOLOGY?
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Physiology focus on How organisms, organ
systems, organs, cells, and bio-molecules carry
out the chemical or physical functions that exist
in a living system
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• PLANT PHYSIOLOGY

• Closely related fields include
• plant morphology (structure of plants),
• plant ecology (interactions with the
  environment) 
• phytochemistry (biochemistry of plants), 
• cell biology,
• genetics,
• biophysics
• molecular biology.

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What kind of unique bioprocesses do plants have?

• Photosynthesis, 
• Respiration, 
• Plant nutrition, 
• Plant hormone functions, 
• Tropisms,  (in latin, tropos, a turning)
• Nastic movements, movements are non-directional
  responses to stimuli (e.g. temperature, light
  irradiance),
• Photoperiodism,  physiological reaction of
  organisms to the length of day or night
• Photomorphogenesis, 

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What kind of unique bioprocesses do plants have?

• Circadian rhythms,
• Environmental stress physiology,
• Seed germination, 
• Dormancy and stomata function and transpiration,
• Dormancy is a period in an organism's life
  cycle when growth, development, and (in animals)
  physical activity are temporarily stopped
• Plant water relations

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Plants range in size from less than 1 cm tall to
greater than 100 m
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duckweed (Lemna)
1 cm tall
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Giant Saguaro Cactus
20 meters Located in Arizona, California,
Sonoran Desert
Surprise Saguaros, besaball team
Edible fruits
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spines are sometimes used as sewing needles
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Redwood Tree Servi agaci
http//www.youtube.com/watch?vC9LHjV48e9s
Helios - 114,58 meter Location Redwood Creek ,
California, ABD
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Modern Plant Physiology A highly
interdisciplinary field

• Physiology
• Biochemistry
• Genetics
• Molecular Biology
• Biotechnology
• Structural Biology
• Developmental Biology

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What is Plant?
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• Why Study Plants?
• B. Fibers--
• 1. Cotton
• 2. Paper Average paper
• 3. Fibers such as nylon and
• rayon are processed from
• wood fibers.

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• Why Study Plants?
• Other molecules
• A. Medicines
• Also noteworthy are aspirin, ephedra (banned),
• quinine, ginkgolides, and others.

Foxglove (Digitalis lanata) produces digitoxin,
which treats heart disease (congestive heart
failure).
Taxol from the bark of the pacific yew tree
(Taxus bacata) is one of the most promising
anti-cancer drugs.
Rosy periwinkle from Madagascar treats two
cancers juvenile leukemia and Hodgkins disease.
Threatened by increasing population.
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• Why Study Plants?
• B. Spices
• C. Oils
• D. Essential amino acids--There are 8 amino
  acids that we need in our cells, but we dont
  have the ability to produce them ourselves.
• We can most easily get them
• from plants. To get the complete
• set of essential amino acids,
• a combination of
• legumes and cereals is best.

E. Fossil fuels like coal, crude oil, and
natural gas are the products of plants that died
a long time ago.
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Some hot areas in plant and nutrient research

• Improving plant water-use efficiency
• Improving salt tolerance
• Improving nutritional value of plants (e.g.,
  golden rice, increasing Fe content)
• Phytoremediation

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• An Overview
• to
• Plant Structure

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Bryophytes

• Small (rarely more than 4 cm in
  height), very simple land plants, and the least
  abundant in terms of number of species and
  overall population.
• Bryophytes include mosses,
• These small plants have life cycles that depend
  on water during the sexual phase.
• Water facilitates fertilization, the fusion of
  gametes to produce a diploid zygote,
• Bryophytes are like algae in other respects as
  well They have neither true roots nor true
  leaves, they lack a vascular system, and they
  produce no hard tissues for structural support.
  The absence of these structures that are
  important for growth on land greatly restricts
  the potential size of bryophytes,
  which, unlike algae, are
  terrestrial rather than aquatic.

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Marchantia, a liverwort, koyun otu
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Mosses, karayosunu
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Hornworts (boynuz otu) are the third group of
bryophytes
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Ferns

• Represent the largest group of
  spore-bearing
• vascular plants. In contrast to
  the bryophytes, ferns have true roots, leaves,
  and vascular tissues, and they produce hard
  tissues for support. These architectural features
  enable ferns to grow to the size of small trees.
  Although ferns are better adapted to the
  drying conditions of terrestrial
  life than
  bryophytes are,
• They still depend on water as a medium for
  reproduction.
• This dependence on water during a critical
  stage of their life cycle
  restricts the
  ecological range of ferns to relatively
  moist habitats.

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The Seed Plants

• Seed plants have been able to adapt to an
  extraordinary range of habitats. The embryo,
  protected and nourished inside the seed, is able
  to survive in a dormant state during unfavorable
  growing conditions such as drought. Seed
  dispersal also facilitates the dissemination of
  the embryos away from the parent plant.
• Another important feature of seed plants is their
  mode of fertilization. Fertilization in seed
  plants is brought about by wind- or
  insect-mediated transfer of pollen, the
  gamete-producing structure of the male, the
  stamen,

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The Seed Plants

• The most successful terrestrial plants.
• Seed Plants need to produce seeds
• WHY they need to do it?

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The Seed Plants

• There are two categories of seed plants
• Gymnosperms (from the Greek for "naked seed")
• Angiosperms (based on the Greek for "vessel
  seed," or seeds contained in a vessel).
• Gymnosperms About 700 species are known. The
  largest group of gymnosperms is the conifers
  ("cone-bearers"), which include such commercially
  important forest trees as pine, fir, spruce, and
  redwood.
• Two types of cones are present
• male cones, which produce pollen,
• female cones, which bear ovules.
• The ovules are located on the surfaces of
  specialized
• structures called cone scales..

CYCAD-Ceratozamia mexicana
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New Jerseys native Pitch Pine, for example, will
remain closed on the tree for years until exposed
to temperatures over 130oF.  The strategy here is
that the tree will not release seeds until after
a forest fire has burned the twig and leaf debris
from the forest floor, making the site suitable
for seedling germination and growth.
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• Angiosperms (based on the Greek for "vessel
  seed," or seeds
  contained in a vessel).
• Angiosperms
• Today, they dominate the landscape and about
  250,000 species are known, but many more remain
  to be characterized.
• The major innovation of the angiosperms is the
  flower hence they are referred to as flowering
  plants.
• Angiosperms are divided into two major groups,
• Dicotyledons (dicots)
• Monocotyledons (monocots)
• This distinction is based primarily on the number
  of cotyledons, or seed leaves. In addition, the
  two groups differ with respect to other
  anatomical features, such as the arrangement of
  their vascular tissues, and their floral
  structure.

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Review of plant anatomy

• Leaves
• Vascular tissues
• Cuticle
• Mesophyll layer
• Stomates and guard cells
• Stems
• Vascular bundle
• Roots
• Lateral roots
• Taproots
• Root hairs

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Meristem

• Localised developmental cells
• Apical meristems
• Stem tips (longitudinal development-elongation-up)
  
• Root tips (longitudinal development-elongation-dow
  n)
• Nodium (formation of branches)
• Lateral Meristem
• Vascular cambium
• Bark cambium
• Pericyle
• (In root-inner meristematic layer)

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Tissues in Plant

• A) Dermal tissues
• Epidermis
• B) Ground tissue
• Paranchyma-photosyntesis
• Collenchyma-support-primary development-alive
• Sclerenchyma-support-secondary development-death
• Sclereids
• Fibers
• C) Vascular tissues
• Ploem
• Xylem

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Cross section of root

• Vascular bundle (Stele) contains xylem and
  phloem
• Cortex
• Epidermis
• Root hairs
• Absorb water and minerals

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Stems

• support leaves to maximize light absorption
• part of conduit for transport of water, minerals,
  and organic solutes
• storage

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Cytokinesis in animal and plant cells
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Fig. 7.1
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Fig. 7.22
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Plant vs. animal cells

• Plant
• Cell wall
• Plastids
• Tonoplast
• Divide by inserting wall
• Plasmodesmata
• Ergastic deposits common
• Modular construction
• Stem cells common
• Totipotent cells common

• Animal
• No cell wall
• No plastids
• No tonoplast
• (lysomes instead)
• Divide by pinching
• Gap junctions
• Deposits rare
• Non-modular
• Stem cells rare
• No totipotency