Re: Iris seeds germinating

 

That's right, Sean.
 
Back in 1976-1978, the group I was in  during grad school was crossing barley with wheat and rye.  The few that sstarted to make seeds would abort at about 2 weeks.  And the embryoes would be small for their age.  With complete fertilizer and complete protein (chemically digested milk protien) and sugar for energy, some would grow to maturity, and some of those would themselves make seeds.  We got an average of 1 second generation plant per year.  Another student and I figured there was $40,000 spent on  wages alone per second generation seed.  Lab space, chemicals, etc., was not included.
 
Today, it is much easier to do embryo culture and sterile seed culture.
 
On the other hand, when corn (Zea mayze) and eastern gama grass (Tripsicum dactyloides) are crossed, one gets an embryo with no endosperm.  But in this case, place the bare embryo (it hasn't the strength to push through the seed coat) half into a sterile potting medium, and it will grow.
 
I have no idea whether embryo culture would have been needed for your embryo, or if maybe sterile conditions and stuck into a sterile potting mix would have worked.
 
I remember Dr. Gill telling me back in about 1983 that he'd found that sugar and agar (agar gells the sugar-water) was enough to greatly increase the frequency of spouting hybrid embryoes.  I think he assumed I'd know to keep the work sterile. He was a plant pathologist crossing wheat with wild wheat relatives to bring in genes for disease resistance.
 
Another reason for embryo culture is that if you want to double chromosomes, you should treat the embryo as soon as possible, when there are as few cells as possible.  This is because the doubled cells don't grow as fast as the normal diploid cells.  So the diploid cells generally take over the meristem and the reproductive parts of the plant are diploid.  The earlier you treat the growing embryo, the better percent tetraploids result.  I want to treat seeds just as the seedcoat is starting to bread open.  Even a little bit sooner.
 
So my reason for doing embryo culture. or just plain sterile seed culture, is to rescue embryoes that won't otherwise make it, and to double chromosomes.
Walter Pickett

From: Sean Zera <zera@umich.edu>
To: iris-species@yahoogroups.com
Sent: Saturday, January 5, 2013 9:44 AM
Subject: Re: [iris-species] Iris seeds germinating
 
I produced almost no seed this year due to the crazy spring weather that destroyed most of the state's orchard crop. However, I did get three undersized seeds on a wide tectorum cross. Opening one up, it seemed to have a normal embryo but no endosperm. This is exactly the sort of thing tissue culture is good for, right?

Sean Z
Zone 6a
SE Michigan

On Fri, Jan 4, 2013 at 11:37 PM, Kenneth Walker <k*@astound.net> wrote:
 
Hi Walter, Thanks for the pointer to the "home tissue culture group"! I've done some embryo culture with Aril species and Arilbreds with pointers from Jim & Barbara Whitely and hope to do some more experimentation. I reduced contamination problems, in part, by mopping the kitchen (laboratory) floor with a weak bleach solution and running a hepa air filter. I'm looking forward to learning more from the group. Ken Walker

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