GA mutants - summary
CAUER at canr1.cag.uconn.edu
Mon Jan 22 19:36:52 EST 1996
As requested, I am posting a summary of the excellent responses I
received regarding the use of GA mutants for plant physiology labs.
Thanks to those with who responded. There is enough information here
to make several interesting labs. Several people have noted that,
although the mutant lines are available from the ABRC, they only
send a small amount of seeds. Therefore, more seeds must be produced
to use in a large lab class.
Dept. of Plant Science
Univ. of Connecticut
cauer at canr1.cag.uconn.edu
Dear Carol Auer
I've read with great interest your mail on the use of BA mutants for
teaching purposes. I've been thinking of doing the same and I msut
say I just did a trial this term. I have been working as a post-doc
in Nick Harberd's group at the John Innes Centre for Plant Science in
Norwich (Great Britian). The work done was mostly molecular genetics
on the GA deficient and GA insensitive mutants of arabidopsis. My
plan for the use of GA related mutants would be as follows. 1) The
use of a severe mutant like ga1-3 to show that GA deficient plants
cannot germinate without GA. Add GA at a nano to mico molar
concentration to see the dose dependent effect of GA on the
percentage of germination.
2) Remove seed coat from the ga1-3 mutant seeds after imbibition.
This shows that mutant seeds can germinate without GA providing the
seed coat is removed. There must be a GA antagonist in the seed coat
3) Grow on soil ga1-3 plants that have been germinated on GA. Show
that the plant phenotype is severe dwarfism and thre is an altered
flowering response as well. Water with millimolar concentration of
GA within few days there is a spectacular reversion of the phenotype
that goes back to almost wild type. The same can be done on less
severe mutant like ga3, ga4 or ga5.
4) I have been using also GA mutant for genetic purposes. Showing
that GA deficient are recessive mutation. Also I am using gai, that
is impaired in GA response. The mutation is semi-dominant so its a
very interesting model to study. Since I've been working on this
particular mutant during my post-doc I msut say that's my pet
Bio. Mol. Veg.
Universite Joseph Fourier - BP 53X
Hi, I have done some work with ga-deficient mutants in Arabidopsis.
ga1 is probably the best mutant. I use 25 micromolar GA4+7 to rescue
for germination. GA3 is available from Sigma, and should work well.
Bump up the concentration to 50-100 micromolar. GA dissolves in
dimethyl formamide. I also have sprayed the non-elongating bolts and
have rescued them in that way. I would try a similar concentration
of GA in a spray bottle. Again, first dissolve GA in DMF, and then
dilute in H2O. Good luck,
Dear Dr. Auer,
I have some experience working with Arabidopsis GA mutants. To
answer your questions on the net:
1. ga1, ga2 and ga3 require exogenous GAs for germination and require
GA treatment to set seed. ga4 and ga5 do not.
2. On plant height, ga1, ga2 and ga3 are severe dwarf. ga4 and ga5
are only semi-dwarf. They all respond to GAs with shoot elongation.
3. the GA concentration that I use is 0.01 mM GA3. Spray plants 2-3
times each week since seed germinates.
Dept. of Molecular Biology
Massachusetts General Hospital
Boston, MA 02114
chiang at frodo.mgh.harvard.edu
I use the ga1, ga4 and ga5 mutants of Arabidopsis in my research.
ga1 lacks ent-kaurene synthase A, probably a single copy gene, and so
is an exteme dwarf, requiring added GA for germination, bolting and
flower development. ga and ga5 lack 3b-hydroxylase and 20-oxidase,
respectively, and are semi dwarf, completing their life cycles
without needing extra GA. The 20-oxidase has at least 3 genes
expressed in different tissues, and it's assumed that the 3b-
hydroxylase must also have more than one gene, although only one has
You can germinate ga1 in the soil by application of 10 uM GA3
(dissolved in EtOH then dilute in water), but this sometimes carries
over into the rosette, promoting flowering and bolting.
Alternatetively, you can germinate the seeds on filter paper soaded
in the GA solution and transplant, or imbibe the seeds in water with
GA for 1-2 days. I use a spray of 10uM GA3 for inducing flowering
etc on all the mutants. They show a measurable response within 4
days, best observed after a week.
Paclobutrazol is applied as a pot drench as its taken up through the
roots. You need to apply for some time to see an effect - I can get
full details if you need them.
University of Bristol
IACR-Long Ashton Research Station
Bristol, BS18 9AF, UK
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