[NAFEX] sports and mutations, more

Lon J. Rombough lonrom at hevanet.com
Sun Mar 20 21:20:31 EST 2005


Heron:
	Where did THIS come from?  You've asked something that would take a 
small book to answer.
Here are a FEW points just to get the ball rolling.
1.  Some "adventitious" buds are really very old buds buried deep in 
the wood.  Laid down when the tree is young, they usually don't push 
unless something very drastic happens to the tree.  These are the ones 
that produce sports most often as the older the bud, the more likely it 
has been hit by radiation, etc. during it's existence, causing a 
mutation.  A great number of bud sports of Red Delicious trace back to 
a severe winter in Washington in the 1950's that froze back many trees, 
causing old buds to push from deep inside the wood.
2.  True adventitious buds arise from undifferentiated (callus} tissue, 
usually from near a wound.
3.  Many plants have different layers of tissue that are actually 
genetically different.  In old types of thornless blackberries, only 
the surface layer was genetically thornless, the internal tissues were 
thorny.  Cut a root and a new shoot would push from an internal layer 
of tissue that was genetically thorny, giving rise to a thorny shoot.  
Use "Chimeras in plants" in a search engine and you should find more 
about this.
4.  In seedling trees, most trees go through a juvenile stage in which 
they may actually be different in appearance from the adult stage.  As 
the tree grows it  becomes mature, but the juvenile stage is still 
there.  Case in point, many Eucalyptus trees have a juvenile stage with 
round leaves, but develop leaves of other shapes as they mature.  But 
cut the tree down to the height at which it was still juvenile and the 
new shoots will be juvenile for a while, having to grow back out of it.
5.  Cut a tree root and force a shoot from it and the shoot will often 
be juvenile and have to grow up just like a seedling, to get to the 
mature phase all over.  One good thing is that cuttings from juvenile 
trees can usually be rooted more easily than ones from mature trees.  
This has been used to propagate trees from cuttings that usually don't 
work that way.  Layer a mature shoot to get it on it's own roots.  Grow 
it until you can get root cuttings from it and grow juvenile phase 
trees from those roots.  Take cuttings of the juvenile phase trees and 
root them.

End of lecture for now.
Someone else can add other stuff.
-Lon Rombough
Grapes, writing, consulting, my book, The Grape Grower, at 
http://www.bunchgrapes.com  Winner of the Garden Writers Association 
"Best Talent in Writing" award for 2003.
On Mar 20, 2005, at 5:59 PM, Heron Breen wrote:

Okay, maybe not news to some, but interesting to me, so I thought I 
would write in:
Terminal Buds (end of shoot wood bud) and Axillary buds (bud situated 
in area where
leaf stem meets the shoot or branch) are both connected to the pithe of 
a Tree
vascular system. An Adventitous bud (bud arising "randomly" from areas 
on older
parts of the Tree and not accompanied by a leaf) is NOT connected to 
the pithe.
This seems to make intuitive sense to me, as the pithe represents the 
conglomerated
metabolic history of a tree, and any bud arising from this layer would 
seem natural
to continue this expression. Meanwhile, the adventitous buds are the 
ones usual
responsible for mutations, ie sports etc, and are arising from where? 
Is it still
in contact with the phloem? Arising from previous years' growth layers?
With roots, I see the term adventitous shoots/buds being used in 
relation to root
cuttings or suckers. These shoots/buds originate in the pericycle and 
vascular ray
tissue, and a few other areas I can't spell. I haven't been able to 
track down the
area(s) in the tissue above the root collar that adventitous buds arise 
from. Does
the word phellogen mean anything to folks?
Another curious query: does the meristem activity in the three types of 
buds
mentioned above differ?
I LOVE the "scientific" use of the word "arise" in relation to celluar 
activity.
Reminds me of the certain religious writings...
Thanks for any and all feedback, just trying to fill in the cracks,
Heron Breen
maine, zone 4



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