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Fernando Migliaccio miglia at nserv.icmat.mlib.cnr.it
Wed Nov 5 11:48:47 EST 1997


Dear Arabinetters,

This message is intended for the people who live in the Southern hemisphere
of the Planet, hoping they can help.
The problem we have to solve regards the handedness of the primary
arabidopsis roots.
In the last few years in fact, some researchers from the Northern
hemisphere, who are actively studying the peculiar right-handed chirality
shown by arabidopsis roots, are constantly asked by other scientists, and
not, if it were possible that the roots can show inverted chirality on the
other side of the earth.  Probably people are referring to the well know
physical process by which a water jet, when falling down, make an inverted
spiral in  the southern side of the earth. We would be thus grateful to
anybody who would like to check the modalities of coiling and slanting of
arabidopsis roots in the Southern hemisphere.
If somebody would like to do this simple experiment, he has to grow the
seeds (possibly of the ecotype Ws, which is highly chiral) on hard-agar
plates (1.5 % agar, 1 % sucrose, 2.5 g/l MS medium).  After a few days, the
plate should  be set either  horizontal or tilted at least 50 degrees on the
horizontal plane, and the root have to be left growing until they slant to a
side or make coils. After one or two weeks about the chirality can be
checked. This has to be done by observing the direction of the slant, or of
the coils,  when looking at the plant from the top, by setting the petri
dish with the lid directed away from the viewer, and the bottom toward him
(in this case the roots appear to grow forward and slant or coil to the
right-hand (in the northern hemisphere).  Possibly, on the southern part of
the earth the direction of coiling is opposite.
By the way, there are a few described  mutants that slant to the left-hand
(1-6C, spr1, and spr2).
More information about arabidopsis root chirality can be found in the
following publications: Mirza, Plant Physiol. 83: 118, 1987; Okada and
Shimura, Science 250: 274, 1990; Simmons, Soell, Migliaccio, J. Exp. Bot.
46:143,1995; Masson and Rutherford, Plant Physiol. 111: 4090, 1996;
Marinelli et al. Planta, 202: 196, 1997 ( in spite of the fact that all
these people gave somehow different and contrasting interpretations of the
arabidopsis root movements, they seem to agree on one point: the
right-handedness of arabidopsis slanting and coiling).
Personally, I do not believe the inversion possible, since the chirality of
arabidopsis roots looks as a genetically fixed characteristic, but in
science nothing can be established  without experimentation !
I thank anyone who would like to do the above experiment for all the people
who asked me, for my colleagues, and for myself.

Gook luck !


* Dr. Fernando Migliaccio               *
* Institute of Plant Biochemistry       *
* and Ecophysiology/ CNR                *
* Via Salaria Km. 29.300                *
* 00016 Monterotondo (Roma), Italy      *
* ph:+39 6 90672530; fax:+39 6 9064492  *
* email: miglia at nserv.icmat.mlib.cnr.it *

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