The Fertile Families
- and Beyond
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The
concept of a Fertile Family, members of which produce more members of the
same family when intercrossed, has been used by hybridizers for decades to
describe the more intricate workings of wide crosses.
In its
most precise form, a separate symbol is used for each aril species.
The more general version, however, recognizes only aril and bearded
chromosome sets and makes no distinctions among the many different types
in each group. This simplifies to only 12 types involved in
producing arils and arilbreds.
|
Type |
Description |
Functional Gametes |
AA
|
Diploid
Aril |
A |
AAA |
Triploid Aril |
A & AA |
AAAA |
Tetraploid Aril |
AA |
AB |
Diploid Arilbred |
A & B |
AAB |
Triploid Arilbred |
A & AB |
ABB |
Triploid Arilbred |
AB & B |
AAAB |
Tetraploid Arilbred |
AA and AB |
AABB |
Amphidiploid Arilbred |
AB |
ABBB |
Tetraploid Arilbred |
AB & BB |
BB |
Diploid Bearded |
B |
BBB |
Triploid Bearded |
B & BB |
BBBB |
Tetraploid Bearded |
BB |
That
may still seem like a lot, but when these crosses are charted they sort
themselves out quite neatly into manageable categories.
In
the chart below,
the parental types are shown as both row and column labels.
If you pick a column corresponding to one type and a row
corresponding to the other, the cell where they intersect gives the
results of that cross – the possibilities,
not the expected ratios. Fertile
families are shown in light green and the relatively infertile
intermediate types in yellow. Other
color codes are explained in the categorical descriptions below the chart.
Clickable links lead to the corresponding Photo Gallery.
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AA
|
AAA
|
AAAA
|
AB
|
AAB
|
ABB
|
AAAB
|
AABB
|
ABBB
|
BB
|
BBB
|
BBBB
|
AA
|
AA
|
AA
AAA
|
AAA
|
AA
AB
|
AA
AAB
|
AB
AAB
|
AAA
AAB
|
AAB
|
AAB
ABB
|
AB
|
AB
ABB
|
ABB
|
AAA
|
AA
AAA
|
AA
AAA
AAAA
|
AAA
AAAA
|
AA
AB
AAA
AAB
|
AA
AAA
AAB
AAAB
|
AB
AAB
AAAB
|
AAA
AAB
AAAA
AAAB
|
AAB AAAB
|
AAB
ABB
AAAB
AABB
|
AB
AAB
|
AB
AAB
ABB
AABB
|
ABB
AABB
|
AAAA
|
AAA
|
AAA
AAAA
|
AAAA
|
AAA
AAB
|
AAA
AAAB
|
AAB
AAAB |
AAAA
AAAB
|
AAAB
|
AAAB
AABB |
AAB
|
AAB
AABB
|
AABB
|
AB
|
AA
AB
|
AA
AB
AAA
AAB
|
AAA
AAB
|
AA
AB
BB
|
AA
AAB
AB
ABB
|
AB
AAB
BB
ABB
|
AAA
AAB
ABB
|
AAB
ABB
|
AAB
ABB
BBB
|
AB
BB
|
AB
ABB
|
ABB
BBB
|
AAB
|
AA
AAB
|
AA
AAA
AAB
AAAB
|
AAA
AAAB
|
AA
AAB
AB
ABB
|
AA
AAB
AABB
|
AB
AAB
ABB
AABB
|
AAA
AAB
AABB
AAAB |
AAB AABB
|
AAB
ABB
ABBB
AABB
|
AB
BBB
|
AB
ABB
ABBB
|
ABB
ABBB |
ABB
|
AB
AAB
|
AB
AAB
AAAB
|
AAB
AAAB
|
AB
AAB
BB
ABB
|
AB
AAB
ABB
AABB
|
BB
ABB
AABB
|
AAB
ABB
AABB AAAB
|
ABB
AABB
|
ABB
AABB ABBB
BBB
|
ABB
BB
|
BB
BBB ABB
ABBB
|
BBB
ABB
|
AAAB
|
AAA
AAB
|
AAA
AAB
AAAA
AAAB
|
AAAA
AAAB
|
AAA
AAB
ABB
|
AAA
AAB
AABB
AAAB
|
AAB
ABB
AABB AAAB
|
AAAA
AAAB
AABB
|
AAAB
AABB
|
AAAB
AABB ABBB
|
AAB
ABB
|
ABB
ABBB ABB
ABBB
|
AABB
ABBB
|
AABB
|
AAB
|
AAB
AAAB
|
AAAB
|
AAB
ABB |
AAB AABB
|
ABB
AABB
|
AAAB
AABB
|
AABB
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ABBB
AABB
|
ABB
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ABB
ABBB
|
ABBB
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ABBB
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AAB
ABB
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AAB
ABB
AAAB
AABB
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AAAB
AABB
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AAB
ABB
BBB
|
AAB
ABB ABBB
AABB
|
ABB
AABB ABBB
BBB
|
AAAB
AABB ABBB
|
ABBB
AABB
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BBBB
ABBB
AABB
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ABB
BBB
|
ABB
ABBB BBB
BBBB
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ABBB
BBBB
|
BB
|
AB
|
AB
AAB
|
AAB
|
AB
BB
|
AB
BBB
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ABB
BB
|
AAB
ABB
|
ABB
|
ABB
BBB
|
BB
|
BB
BBB
|
BBB
|
BBB
|
AB
ABB
|
AB
AAB
ABB
AABB
|
AAB
AABB
|
AB
ABB
|
AB
ABB
ABBB
|
BB
BBB ABB
ABBB
|
ABB
ABBB ABB
ABBB
|
ABB
ABBB
|
ABB
ABBB BBB
BBBB
|
BB
BBB
|
BB
BBB
BBBB
|
BBB
BBBB
|
BBBB
|
ABB
|
ABB
AABB
|
AABB
|
ABB
BBB
|
ABB
ABBB
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BBB
ABB
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AABB
ABBB
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ABBB
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ABBB
BBBB
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BBB
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BBB
BBBB
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BBBB
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The
symmetry of the chart may not be immediately obvious because the cells
aren't square, but if we also ignore the direction of the cross we need to
deal with only 78 different types of crosses that fall into five
categories. The simplest
cases, crosses within type, appear along the diagonal.
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Crosses
Within the Fertile Families
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Five
of these are crosses within one of the familiar fertile families:
the diploid arils, tetraploid arils, amphidiploidlike arilbreds,
diploid beardeds, and tetraploid beardeds.
All offspring from such a cross have the same type of chromosome
complement as their parents, which makes them by far the easiest to work
with. Like their parental types, these are shown in light green. They
yield a high percentage of takes and produce full pods.
Their seeds exhibit relatively good germination and their seedlings
have highly predictable results. Entire programs can be conducted working
within one of these cells. |
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Crosses
Within a Relatively Infertile Type
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The
other seven
along the diagonal are crosses between two members of the same relatively
infertile group. Because
neither parent is fully fertile, the chances of getting any offspring at
all are slim. In fact, it was this contrast that led many to label the
intermediate types as “sterile” when the concept of Fertile Families
became widely used. Intermediate
types like this, however, are capable of producing two different types of
gametes – so such a cross can produce three types of offspring: the
parental type or either of the ancestral types. These crosses are shown in
brown.
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Crosses
Between the Fertile Families
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Ten
more are crosses between two of these fertile families.
They also have predictable results because all of the offspring
from a cross between two such families have the same type of chromosome
complement. Of these, one
produces offspring that are members of a fertile family other than that of
either parent while the other nine produce relatively infertile
intermediate types. These are
shown in green and yellow, respectively.
Some of these have also been quite popular because they reliably
produce valued garden subjects like 1/4-breds and 3/4-breds. A great deal
can be accomplished without venturing beyond this category into the world
of more complex crosses.
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Crosses
Between a Fertile Family and a Relatively Infertile Type
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Thirty-five
are crosses between a member of one fertile family and a relatively
infertile type. These are
somewhat more complicated than working within or between fertile families
because the relatively infertile partner produces two types of gametes and
the seedlings thus fall into two types. The real challenge comes in
evaluating the seedlings for possible registration because sibs may have
different chromosome complements and thus belong to different registration
classes. Although this group is more difficult to work with, there is
enough fertility to make it worthwhile for the adventuresome.
These cells are shown in dark green.
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Crosses
Between Two Different Relatively Infertile Types
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The
final 21 are the widest type of cross.
The odds are greatly against getting any offspring at all, but
because each parent produces two types of gametes. Because the two
parents do not necessarily produce any gametes of the same type, however,
some very interesting recombinations can occur.
For example, crossing a triploid aril with a triploid bearded could
produce four types of arilbreds: an AB-type diploid, ABB- and AAB-type
triploids, or an AABB-type amphidiploid.
These crosses are shown in gray.
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