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[Arabidopsis] brands of agar

Tobias Baskin via arab-gen%40net.bio.net (by baskin from bio.umass.edu)
Wed Feb 13 09:29:26 EST 2008


Greetings,
	In replies to this thread, Grant Cramer mentions "PhytoAgar" 
and Brian Forde mentions "PhytagelTM" which I think is the same 
phytagel we used awhile back too. But is PhytoAgar the same stuff as 
Phytagel? or are they different? Do you know?

	Thanks,
		Tobias

At 4:40 PM -0800 2/12/08, Grant Cramer wrote:
>I have found very negative effects on root growth using BactoAgar 
>both from batches in the United States and Australia. I have NEVER 
>had a problem with PhytoAgar on root growth in root length assays up 
>to a week. After that they are in the dish for too long and will 
>suffer. One can supplement with sucrose in a standard quarter 
>strength Hoaglands solution without problem. I agree you should not 
>use MS medium or you will suffer from osmotic stress and perhaps 
>other things that are out of balance for roots. The roots will grow 
>without the sucrose but slower. It depends on your experiment, but 
>those shaded cotyledons in a plastic petri dish can only do so much 
>in the dark or dim light. I always grow them in the dark, as light 
>inhibits root growth.
>
>Grant R. Cramer
>Professor
>Department of Biochemistry and Molecular Biology, MS 200
>University of Nevada, Reno
>Reno, NV 89557
>(775) 784-4204
><mailto:cramer from unr.edu>cramer from unr.edu
><http://www.ag.unr.edu/cramer/>http://www.ag.unr.edu/cramer/
>
>
>
>On Feb 11, 2008, at 6:33 AM, Tobias Baskin wrote:
>
>>Dear Tanya,
>>	Some years ago, we investigated a variety of different agars 
>>(some of which you mention). We found reproducible differences in 
>>root elongation rate but perhaps on the order of 10 to 20 %. 
>>Clearly the roots liked some agar better than others. We also found 
>>a little bit later when using phytagel that root elongation rate 
>>depended on the temperature the molten mix was held at before 
>>pouring, or might have simply been quite irreproducible. But again 
>>I am talking about differences on the order of 20%. Big enough to 
>>readily measure but not monstrous. On no agar did we see the kind 
>>of developmental change you are mentioning. On some conditions I 
>>have seen (and read) that severely salt stressed or water deficit 
>>stressed roots will swell so I'd guess what you are describing goes 
>>way beyond what can be expected from different brands/formulations 
>>of agar.
>>
>>	Hope this helps,
>>			Tobias
>>
>>At 3:10 PM -0600 2/9/08, Falbel, Tanya G. wrote:
>>
>>>Colleagues:
>>>
>>>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.
>>>
>>>Thanks
>>>
>>>Tanya Falbel
>>>Department of Biology
>>>105 Garfield Avenue
>>>University of Wisconsin-Eau Claire
>>>Eau Claire, WI 54702-4004,  USA
>>>
>>>Tel: 715-836-5087
>>>Fax: 715-836-5089
>>>
>>>
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>>>
>>
>>
>>--
>>       _      ____          __   ____        /  \   /          / \ 
>>/   \ \        Tobias I. Baskin
>>     /   /  /          /   \   \      \         Biology Department
>>    /_ /   __      /__ \   \       \__    611 N. Pleasant St.
>>   /      /          /       \   \       \        University of Massachusetts
>>  /      /          /         \   \       \	    Amherst, MA, 01003
>>/      / ___   /           \   \__/  \ ____
>><http://www.bio.umass.edu/biology/baskin/>http://www.bio.umass.edu/biology/baskin/
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>>
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