Plant Science

The third and final lecture on plant hormones is about brewing beer and Prince. No, of course not, but both are used as examples for the effects of gibberellins and abscisic acid.

Gibberellins were first discovered in "foolish rice" (or banana) where a fungal infection results in increased levels of gibberellins and very long, extended internodes. They are a large group of compounds (more than 120 gibberellins are known) and also stimulate seed germination, an effect that is taken advantage of in the malting process. Plants with lower amounts of gibberellins are referred to as "dwarf" mutants and have played an important role in the agricultural revolution.

Despite its name, abscisic acid is generally not involved (with a small number of exceptions) in leaf abscission. Instead, it plays a major role in all plant stress-related processes. Most importantly, closure of stomata as a result of waterstress is caused by abscisic acid. Another important role of absisic acid is the delay of seed germination - together with gibberellins this results in a very tight regulation.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

This lecture is about specific effects of two groups of plant hormones: cytokinins, and ethylene.

The main effects of cytokinins are stimulation of cell proliferation, and stimulation of growth of shoots from undifferentiated tissue (callus) in plant tissue culture. Together with auxins, cytokinins regulate apical dominance which determines the growth pattern of plants.

Ethylene is a gas and as such diffuses very easily and quickly. In climacteric fruits like banana or tomato ethylene accelerates the ripening process, and promotes leaf fall and fruit fall (abscission). We also have a look at a couple of mutations called SNORKEL in rice that cause very rapid and extreme elongation of the stem internodes.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

This lecture is about specific effects of two groups of plant hormones: cytokinins, and ethylene.

The main effects of cytokinins are stimulation of cell proliferation, and stimulation of growth of shoots from undifferentiated tissue (callus) in plant tissue culture. Together with auxins, cytokinins regulate apical dominance which determines the growth pattern of plants.

Ethylene is a gas and as such diffuses very easily and quickly. In climacteric fruits like banana or tomato ethylene accelerates the ripening process, and promotes leaf fall and fruit fall (abscission). We also have a look at a couple of mutations called SNORKEL in rice that cause very rapid and extreme elongation of the stem internodes.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

As we saw in previous lectures, plants are "rooted" to one spot. As a consequence they can not avoid adverse conditions such as drought, heat, cold etc. yet are able to survive seemingly extreme conditions. Almost all aspects of plant development and physiology are influenced and directed by plant hormones.

In today's lecture we look at the discovery of plant hormones in general - watch out for the appearance of an unlikely scientist - and look at specific effects of the phytohormone auxin, such as phototropism in shoots and geotropism in the roots, and apical dominance.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

As we saw in previous lectures, plants are "rooted" to one spot. As a consequence they can not avoid adverse conditions such as drought, heat, cold etc. yet are able to survive seemingly extreme conditions. Almost all aspects of plant development and physiology are influenced and directed by plant hormones.

In today's lecture we look at the discovery of plant hormones in general - watch out for the appearance of an unlikely scientist - and look at specific effects of the phytohormone auxin, such as phototropism in shoots and geotropism in the roots, and apical dominance.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Plants can't do it all by themselves. In order to get the most out of the soil and, indeed, the air, most plants form symbiotic relationships with bacteria and fungi. We take a look at Anabaena, root nodules, and mycorrhizae.

Roots are often modified to form "survival structures" containing sugars or proteins. Carrots, cassava, batata and yam are typical examples that are used as food sources by humans.

In the last part of this lecture we briefly touch on global and local soil problems like erosion, lack of nutrients, and excess of minerals that increases soil toxicity.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Plants can't do it all by themselves. In order to get the most out of the soil and, indeed, the air, most plants form symbiotic relationships with bacteria and fungi. We take a look at Anabaena, root nodules, and mycorrhizae.

Roots are often modified to form "survival structures" containing sugars or proteins. Carrots, cassava, batata and yam are typical examples that are used as food sources by humans.

In the last part of this lecture we briefly touch on global and local soil problems like erosion, lack of nutrients, and excess of minerals that increases soil toxicity.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Roots anchor plants in soil, are responsible for the uptake of water and nutrients, and control which molecules are ultimately taken up by the plant.

In this lecture we take a look at the root morphology of monocots and dicots, how lateral roots aad root hairs are formed, and describe different pathways for the transport of water and solutes in the roots.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Roots anchor plants in soil, are responsible for the uptake of water and nutrients, and control which molecules are ultimately taken up by the plant.

In this lecture we take a look at the root morphology of monocots and dicots, how lateral roots aad root hairs are formed, and describe different pathways for the transport of water and solutes in the roots.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.

Roots anchor plants in soil, are responsible for the uptake of water and nutrients, and control which molecules are ultimately taken up by the plant.

In this lecture we take a look at the root morphology of monocots and dicots, how lateral roots aad root hairs are formed, and describe different pathways for the transport of water and solutes in the roots.

Copyright 2012 La Trobe University, all rights reserved. Contact for permissions.