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Re: Re: HYB: 2nd year sprouts
  • Subject: Re: Re: HYB: 2nd year sprouts
  • From: Chuck Chapman <irischapman@aim.com>
  • Date: Fri, 25 May 2012 17:00:28 -0400 (EDT)


The genetic factors related to needing less vernalization are a set of
genes completely unrelated to the triggers for bloom time. So no
possible relationship involving genetic correlation. Completely
different pant hormone/trigger systems.

No relationship between germination time and bloom time.

Any inbreeding depression is removed by breeding to another unrelated
genetic line. Doesn't need a wide variation in other parent. There
are charts in genetic textbooks showing all this.

An example from a previous hobby of aquarium fish. A breeder of
guppies had two inbred lines of guppies. both showed inbreeding
depression. No show qualities in ether line. To produce show winning
guppies, he crossed the two lines. The offspring were marvelous, and
had show winners in every batch.

Two inbreeding depression lines have different genes being depressed,
especially on the mutifactor sets.

Inbreeding depression, is not the same as factors linked by having
genes closely aligned physically on same chromosome. So factors
associated together in a line are likely a genetic depression. That is
a limit of alleles available in the line as these factors were not
taken into consideration during parental selection, and traits lost.
So the traits are inherited together by limits of genes available.

The differences reported involved several different factors. The just
couldn't be possible all be linked.

Year one versus year two, are two random samples from one gene pool
(supposedly). You can't get even one of these factors to sort this way
randomly. And even if one or two traits were linked (unlikely) that
would leave others to be random. Way beyond probability.

TB iris are no longer considered amphidiploid, A cross between
tetraploid aphylla and a TB may be ampjdiploid in first few
generations. Four sets of 12 chromosomes.

SDB are amphidiploid, as they have two sets of 8 and two sets of 12
chromosomes. So they always separate into gametes with one set of 8 and
one set of 12.

All my genetics and statistic forensics say these two samples are not
from same two parents.

Chuck Chapman

From: Linda Mann <lmann@lock-net.com>
To: iris-photos <iris-photos@yahoogroups.com>
Sent: Fri, May 25, 2012 10:42 am
Subject: [iris-photos] Re: HYB: 2nd year sprouts

&gt; &gt; Inbreeding depression. T During this process secondary traits
such as
&gt; germination, branching (cold hardiness) etc can loose some of its
&gt; variability and get trapped into a restriction. This can only be
&gt; by crossing into a line that does not have this problem, and
&gt; carefully on this trait.

Right, that's what I was saying (or trying to say).

&gt; So, for example, inbred pink lines can end up with a trait which
&gt; requires less vernalization for germination. But when lines are
&gt; crossed, these traits will become less distinct.

But only if they are crossed with cultivars with a range of
characteristics - my impression is that pinks (for example) were inbred
for a long time. Added limitation of bloom season - most crosses are
made between cultivars that are blooming at the same time.

[My impression is that the earliest germinants - by early in this case,
I mean early in the season, i.e., cooler temperatures (?) - are also
early bloomers - no idea if this is true - anybody have data?]

&gt; While some traits can be located close to others, and be linked, in
&gt; this situation, this is a less likely scenario, although possible.
&gt; The tangerine factor, for instance, has been noted , by you, as
&gt; needing less vernalization for germination. Likely a variability
&gt; selected out. So if linked, a group of seedlings having some
&gt; tangerine factor and some not having ( as in example being
&gt; the tangerine factor seeds would germinate faster ,and be more
&gt; represented in first year germination, rather then in second year
&gt; germination.

Some blurring here - there seem to be a lot of late blooming t factor
cultivars that are &lt;not&gt; pink. Part of what makes me suspect the
germination/low chilling requirement for (some/most/sure not all?)
is just a coincidence of origin. So might be the 'white' genes
of anthocyanin) associated with tangerine in those early pinks. So
early &lt;pinks&gt; is not opposite of report from Mary Lou.

&lt;The opposite of what was reported.&gt;

I understand that.
&gt; Then we have to look at math. Probabilities and distribution
&gt; That is all offspring of a cross will be on a distribution curve.
&gt; a mean and a standard deviation, for all traits involving multiple
&gt; genes. For example petal width, petal size, petal strength. So when
&gt; one group of seedlings has one set of means and SD, different then
&gt; separate set, then probability of being samples from same
&gt; set becomes extremely low.

Right, I'm suggesting it's not random.

&gt; So you are not going to get a set of poor seedlings for one year
&gt; (one sample set) and a set of good seedlings in second year (second
&gt; sample set), by random.

I'm not sure I follow this - seems to contradict what you were saying
earlier about inbreeding and suppression of variability.

Staying with pinks for the moment, very very few pinks have much, if
resistance to foliar 'summer crud' - bacterial/fungal leaf spot. (I
haven't tried to separate out the two here - local extension folks say
it's bacterial, all irisarians say its fungal, I just call it crud).
color and susceptibility to crud may not be 'linked' (i.e., on the same
chromosome), but they do co-occur.

Assuming you are correct in saying they are not genetically linked, can
you come up with some other explanation for skewed distribution of
co-occurring vegetative (health, temperature regulation) and
color/pattern traits? Or are you saying that it just doesn't exist.

If we are looking at possible genetic linkage,
&gt; then there would have to be linkage of tangerine factor, and
&gt; genes associated with substance and petal size linked with each
&gt; and with germination factors, such as vernalization genes. Sorry, a
&gt; very improbable situation.

Also, I'm curious how amphidiploid nature of TBs feeds into probability
distribution for traits.

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