Over the years, I've used several brands of agar for growing Arabidopsis seedlings on MS medium,
from Gibco, Sigma, and others. I've heard that some groups use Noble agar,
others, bacto-agar, others in the past have washed their own agar, used phytagel or other
gelling agents. I have two questions:
1) What brands of agar are most commonly in use now by groups? I've found something similar
to Gibco's Phytagar that is now available through Caisson labs. Other groups seem to like Sigma's
A1296. But besides those, what do most groups use? I'm especially interested in the opinion of
groups that measure root length or root branching - growing roots vertically on plates
for more than just a couple of days. (as opposed to just antibiotic selection)
2) Does anyone know what inhibitors are washed away? Are micronutrient ions or other toxic
compounds bound to the crude agar? Has anyone looked into this? This may have been a question
that came up among researchers 10 years ago, but I couldn't find any record in the archives.
Here's why I'm asking. I made up a batch of medium with a brand of 'purified agar for microbial use',
and got a very strong inhibition of root meristems. Seed germination was good, but roots failed to elongate
any further after about 4 days of growth. The root meristems became a swollen mess, reminiscent of what
happens in weak gnom alleles. I'm trying to decide if this is something worth looking into.
I know that for regeneration of plants in tissue culture, folks are very fussy about particular brands of agar.
Please let me know what brands you have used with success or failure.
I'd be especially interested in other similar experiences - where a brand
wreaked havoc on root meristems.
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