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Answers to Andrew ploidy questions


Hello Andrew here some answers
> 
> One of the statements in the article is perplexing to me:
> "Based on the low pollen stainability and seemingly aneuploid offspring,
> 'Sum and Substance' must be considered a triploid. However, the high DNA
> content indicates that H. ventricosa is not one of the parents.
> >  I have to admit that I need some help with the reasoning here.  H.
> ventricosa 'Aureomarginata' shows pg DNA per 2C nucleus at 41.6 and it is
> concluded that this plant is a tetraploid.  H. 'Sum and Substance' shows pg
> DNA per 2C nucleus at 39.0, at the high end of those listed as triploids.
> I'm not questioning the results, I'm just trying to understand how one
> draws the conclusion that 'Sum and Substance' could not have H. ventricosa
> as a parent from the data alone.   Maybe Ben, or someone else, can help me
> out with this.
If ventricosa (41pg)  crosses with another tetraploid plant like some 
Fortuneis (51)The tetraploid offspring will have 1/2 ( 41+ 51) = 46pg.
If ventricosa crosses with a diploid plant let say sieboldiana (25pg) 
the  triploid ofspring will have 1/2 (41+25)=33 pg
So this excludes ventricosa as a parent for S&S (39)
If we cross a tetraploid fortunei like some Patriots with a diploid 
sieboldiana, the triploid offspring will have 1/2 ( 51+ 25) = 38 pg so 
this is most likely.
> There are a couple of places in the Euphytica article where further
> translation into English may be warranted.  This could be part of the
> reason, Ben, that sometimes your articles aren't immediately published in
> the AHS Journal--i.e. the editors are still trying to figure out what you
> are saying.  This could simply be due to translation questions, perceived
> demand for articles of a rather scientific nature (lots of people don't
> even enjoy knowing this much about a plant).  I am not an editor so I am
> uncertain why this could be occurring, but I for one have appreciated
> articles of a more scientific nature, and this certainly includes the only
> two that I am aware of to date.
I did not ask for a full transcript, but just mentioning the fact that an 
article has appeared would have been nice
> This statement is a bit confusing so I could use some help with its
> interpretation:
> pg 108:  "This suggests that the higher DNA content in some cultivars was
> due to an increase with DNA of a similar AT (Adenine-Thymine) content as
> found in the plants with the lower DNA content".
I will try: Most hostas have the same number of chromosomes 
2x=60. Yet there are up to 50 % differences in the amount of DNA 
If this increase would be by only A and T it would have changed the 
DAPI/Pi ratio as Dapi only measures A and T. The ratio did not 
change so the increase was by DNA with the same A T content as 
the original DNA 
> With this one I could use some help also:
> pg 109 (toward bottom left). "The tetraploidy of the L3 is corroborated by
> the roots in which only tetraploid (4C) and 8C cells are present".   --- I
> thought for a moment that the legend for the terms 2C and 4C would be
> 2C=Diploid and 4C=Tetraploid.  However, with the introduction of the 8C
> acronym, now I am uncertain.   (if the C=Chromosomes, what does 8C equal?)
diploid  hosta: 2x = 2n = 60 chromosomes
tetraploid Hosta 2n=4x=120
Flow cytometry doen not give chromsome numbers but the amount 
of DNA so I can only say that the amount of DNA is twice as high 
suggesting a tetraploid For the amount of DNA the C is used So 
8C means 8 times as much DNA as in the gamete ( =C).
> Paul wrote:>>If the generation of polyploids is "common" in tissue
> culture-this might explain why some plants come out of culture and do not grow well.
> This I am curious about as well.  Probably 150 of the 230+ new varieties
> I added this year were TC plants.  I found I had more trouble establishing
> some of the mature crown plants than I did the vast majority of any TC
> stock.   H. longipes 'Aurea', H. 'Lady in Waiting', H. fortunei 'Aoki', H.
> 'Blue Mammoth', and H. 'Aqua Velva', to name a few, were tough to get going
> in their containers.  I did have a couple of TC plants that were harder to
> get going, too, but I attributed this more to their plant lineage than
> having anything to do with them coming from the TC means of propagation.
> Later, I made the same conclusion about the above referenced mature crown
> plants.
As Jim said polyploidy in tc is fairly rare An explanation for the 
slow growing ones could be : selection for plants adapted to tc but 
doing bad in real life This will happen  especially if a tc culture is 
not refreshed regularly 
> For a while, I was looking at a tray of H. 'Big Daddy' (TC plants) and
> saying, "What is wrong with you? Grow, grow!!!".  They looked anemic--no
> growth, the edges of the leaves were browning, and I thought they were
> dying or had contracted some disease.  Eventually, as I was repotting and
> moving some of the blues into the ground for wintering over, I discovered
> that for many of these, all of the growth activity had been going on in the
> root systems--they were just going dormant early but were busy putting on
> "adventitious divisions" (I'm still not certain that I am using this
> terminology correctly.  Anyone wanting to offer concurrance to its proper
> use, or that my useage is abominable, have at it.   Are the divisions that
> emerge from the bottom of a stem "adventitious roots" or adventitious
> divisions", or both?).
All roots in hosta are adventitious roots Divisions or new shoots are 
 like ( very short in the case of hosta)branches in a tree

Ben J.M.Zonneveld
Clusius lab pobox 9505
2300 RA Leiden
The Netherlands
mintemp-16C(5F)
Zonneveld@RULbim.LeidenUniv.NL
Fax: 31-71-5274999
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