TROPISMS

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Phytochemistry 3

• TROPISMS

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Tropisms were first
discussed by Darwin
in 1881 (The Power
of Movement in Plants).

• Tropisms are movements or directional growth in
  direct response to environmental factors

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• Tropisms and
  other
• changes help plants (and other life forms too)
• deal with changing physical factors in their
• environments. These "behaviors" are also
• important for interacting with pollinators,
• predators, seed dispersers, and competitors.

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• be able to explain in simple English HOW
  (mechanisms)
• and
• WHY (specific value to the plant)
• the tropisms and other responses work

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TROPISMS

• Morphogenesis is maybe a better name for tropisms
  or similar responses which involve a change in
  growth
• Nastic movements and ___-nasty are terms
  sometimes used for reversible changes (see chart
  )

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STIMULUS LIGHT?

• Duration (photoperiod) and color and intensity
  all matter. Phytochromes sense red and far-red.
• Two types of receptors are sensitive to blue
  light
• .Phototropins (PHOT1, etc.) are involved in
  phototropism, chloroplast motion toward optimal
  light intensity, and stomatal opening and their
  mutant genes are called nph-1, nph-2 etc. (for
  non-phototropic hypocotyl)
• Cryptochromes (genes called cry-1 etc.) are
  involved in circadian rhythms (in us, too)and
  photomorphogenesis

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To understand tropisms, etc.

• Read some of these
• an easy online textbook like this
  http//www.hcs.ohio-state.edu/hcs300/signal.htm
• and maybe a harder textbook
• like this http//www.rrz.uni-hamburg.de/biologie
  /b_online/e31/31.htm
• or a big botany textbook, preferably less than
  half your age (several are in the lab and one
  should be on your shelf or desk or under your
  bed)

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To understand tropisms, etc.

• Try to translate some excerpts from research
  reports, including those for hormones (above) and
  those on your print-out or at http//www.queens.ed
  u/faculty/jannr/Botany/phytochem.htm.

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To understand tropisms, etc.

• Fill in and learn the chart

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To understand tropisms, etc.

• Ask questions about the chart Friday

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To understand tropisms, etc.

• Listen and watch in class, especially when we
  have videos (http//sunflower.bio.indiana.edu/rha
  ngart/plantsinmotion.html)