Re: Digest for plant_hormones@googlegroups.com - 1 Message in 1 Topic

[hovav חובב `Lerner לרנר‎]

it does not seem likely that Auxin travels sideways, from the sun side to the opposite side.

2011/5/25 <plant_hormo...@googlegroups.com>

  Today's Topic Summary

Group: http://groups.google.com/group/plant_hormones/topics

• Explanations of Gravitropism and Heliotropisim [1 Update]

 Topic: Explanations of Gravitropism and Heliotropisim

socrtwo <soc...@gmail.com> May 24 07:01AM -0700 ^

 
** Phototropism **
 
* Stem Phototropism - Photosynthesis on the side of a plant stem and
leaves facing sunlight increases Oxygen on that side because a product
of Photosynthesis is Oxygen and Auxin I believe is an indicator of
Oxygen surplus. This Auxin is then transported to the shadow side and
growth occurs there bending the plant toward light.
 
* Root Phototropism - a small amount of photosynthesis again occurs in
the top of the root exposed on the surface to light. However the
difference is in the root I hypothesize that no transport take place
or much less transport. So there is a surplus of Auxin stuck on the
surface of the root on the side facing the sun, thus the root grows
down.
 
** Gravitropism **
 
* Stem Gravitropism - Stem or leaves on the ground cause starch
statoliths to fall to bottom of cells. This starch is partially
hydrolyzed and a greater amount of Oxygen respiration occurs on the
bottom. Auxin always travels within stem cells and within larger stem
and leaf structures, from areas of high Oxygen levels to low ones.
Auxin pools on the lower side of the structure where the statoliths
are. The leaf or stem cells lengthen here and the structure grows up.
 
* Root Gravitropism - the same process occurs here with the statoliths
falling to the bottom of the root cells, and a relative Oxygen
depletion occurring there. However no or much slower root Auxin
transport takes place. With a relative paucity of Auxin in the bottom
of the cell compared to the top, causes root cells and larger
structure to lengthen relatively speaking, faster on the side away
from gravity.


 

--
You received this message because you are subscribed to the Google Groups "Plant Hormones and Plant Growth Regulators" group.
To post to this group, send email to plant_h...@googlegroups.com.
To unsubscribe from this group, send email to plant_hormone...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/plant_hormones?hl=en.

--
Hovav Lerner
Tl +972508824060  Fx 153508824060  snail 10 Svedlov st. Gedera israel 70700
רח סברדלוב 10 גדרה 70700
http://hovavlerner.cafe.themarker.com