Download Other Plant Hormones - NCEA Level 3 Biology

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Xylem wikipedia, lookup

History of herbalism wikipedia, lookup

Plant ecology wikipedia, lookup

Plant nutrition wikipedia, lookup

Seed wikipedia, lookup

Botany wikipedia, lookup

Venus flytrap wikipedia, lookup

Historia Plantarum (Theophrastus) wikipedia, lookup

Plant morphology wikipedia, lookup

Plant physiology wikipedia, lookup

Evolutionary history of plants wikipedia, lookup

Auxin wikipedia, lookup

Leaf wikipedia, lookup

Ornamental bulbous plant wikipedia, lookup

Glossary of plant morphology wikipedia, lookup

Plant evolutionary developmental biology wikipedia, lookup

Plant reproduction wikipedia, lookup

Perovskia atriplicifolia wikipedia, lookup

Flowering plant wikipedia, lookup

Transcript
Other Plant
Hormones
Gibberellins
• There are now more than 60 known
gibberellins.
• These cause rapid growth of the
internodes on stems.
– The internode is the region between the
points where the leaves are attached.
– Dwarf plants are often short because
they do not produce enough gibberellin
to form long internodes.
Gibberellins
• These hormones are produced in young
leaves and buds.
• They cause flowering in long-day plants
even when they are kept in short-day
conditions.
• They cause flowering in biennials that
normally need a period of chilling
(vernalisation)
Gibberellins
• They help to mobilise the endosperm
(food reserve) in cereal seeds.
• They promote the germination of a wide
variety of seeds that would otherwise be
hard to germinate.
• They are becoming increasingly important
in industry – e.g. they increase the size of
seedless grapes when sprayed on them.
The Cytokinins
• These are produced mainly in the roots
• They regulate the process of cell division.
• These hormones are found in coconut
milk, fruits, seeds and roots.
Promoting Cell Division
• Cytokinins promote cell division in intact
plants and tissue cultures.
– Relatively high conc of auxin to
cytokinin produces roots in a tissue
culture.
– Higher proportions of cytokinins to
auxins produces buds and leaves.
– Roughly equal concs make callus
tissue (undifferentiated tissue)
Cytokinins
• Cytokinins slow down the process of aging
(senescence) in plants, if applied to
leaves it can prevent the yellowing of
mature leaves in autumn and their
dropping (abscission).
Abscisic Acid
• In general, this functions as an inhibiting
hormone acting against auxin,
gibberellins and cytokinins.
• It plays a role in abscission.
• Dormant buds have relatively high levels
of ABA which drop as spring approaches
• Some dormant seeds also contain
relatively high concs of ABA
Abscisic Acid
• It also seems to have a role in helping
plants to withstand drought conditions, by
affecting transpiration and closing guard
cells of the stomata.
Ethylene Gas
• “one rotten apple spoils the barrel”
• A ripening apple gives off ethylene gas
that ripens adjacent fruit.
• Commercially ethylene gas is important:
– It influences the ripening of fruit
– It helps the harvesting of berries,
causing them to drop.
– It helps the rubber in rubber trees to
flow for longer.
Ethylene Gas
– It increases the sugar content in sugar
cane.
– It promotes flowering of pineapples.
– It accelerates the aging of tobacco
leaves.
Florigen
• The flowering hormone.
• This has not been isolated but there is
evidence that there is a hormone which
induces flowering.