This article is first published in
IPA Journal - Phalaenopsis - Foruth Quarter 2005 issue. Made available
online with permission from the author.
BREEDING FOR TETRAPLOID RED
PHALAENOPSIS – A. Dean Stock, Ph.D.
Diploids, triploids and tetraploids – why breed for tetraploid reds? For
clarification: “n” equals 19, which is the number of chromosomes in either
the pollen or the ovule of a normal diploid phalaenopsis. In a full set of
genetic material, consisting of paired chromosomes, there will be 2n or 38
chromosomes. In a triploid plant, there are 3n or 57 chromosomes, in a
tetraploid, there are 4n or 76 chromosomes, and in an aneuploid, which
results from breeding a diploid or a tetraploid with a triploid, there are
an abnormal or odd number of chromosomes.
The major reasons for breeding towards tetraploid red phalaenopsis is to
increase flower size and to obtain a more standard phal shape. Increased
flower count and better presentation are additional breeding goals.
|Phal Chingruey's Blood Red Sun 'Ching Ruey'
||Phal Ching Hers Goddess 'Lin'
||Phal Brother Passion 'Patricia'
|Phal Brother Precious Stones 'Patricia'
||Phal Strawberry Wine 'Patricia'
||Phal Brother Sally Taylor 'Patricia'
Almost all of U.S. breeding has
been with diploids, triploids, and the aneuploids that have resulted from
breeding triploid reds to diploids and tetraploids. Aneuploids were also
produced through attempts to increase flower size by breeding triploid reds
to tetraploid pinks and stripes.
Diploid red breeding has reached a high level of quality and as we have seen
with Eric Goo’s work, is well worth pursuing. However, great care must be
taken to mate diploids to diploids. The use of plants such as Phal Cordova,
Golden Buddha or Spirit House leads to problems. Most attempts to increase
size and flower count with diploid red breeding lines has resulted in the
production of triploids. Unfortunately, triploid phalaenopsis will often
produce seed, and the results of using “anything that will breed,” has
produced a sea of aneuploids, which are then used in further breeding
attempts. The outcome of this type of breeding is the well-known ‘sterility
barrier’ so common in today’s phalaenopsis breeding.
To give perspective to the problem, consider that a phalaenopsis breeder
with the knowledge and experience of Carlos Fighetti observed in his recent
article in the Phalaenopsis Journal that with the matching of Phal Golden
Buddha with Zuma Garnet, the first of the “new” red phals was produced. More
specifically, the near-tetraploid aneuploid Phal Golden Buddha was crossed
with the diploid Zuma Garnet to produce the aneuploid plants registered as
Phalaenopsis Cordova. Based on what we know about chromosomes and their
relationship to plant sterility, Phalaenopsis Cordova should never be used
for breeding. Crosses of this nature produce dead ends.
The degree to which triploid and aneuploid plants have been used in breeding
for red – and yellows – is such that it is amazing that any fertile plants
can be found. All of this type of breeding should be avoided if one wants to
achieve good-sized red phalaenopsis with other desirable traits and with
fertility the expected norm instead of a rarity. Instead, breeders must rely
on chance tetraploids such as Paifang’s Queen ‘Brother’ and Taipei’s Gold
‘Gold Star’ or documented colchicine-converted diploids. All chance
tetraploids must be documented by accurate chromosome counting. One
additional important concept here is that converting triploids to hexaploids
through colchicine treatment does not produce good breeding plants because
hexaploids do not produce stable, even ploidy in their offspring.
Why consider yellow flowers in red breeding? There is no true red
phalaenopsis in nature. So we create red by combining pigments. Without
strong yellow pigment, you do not obtain strong red color. You need to
produce good tetraploid yellows in order to mate them with tetraploid dark
pinks or lavenders. Where do we get good tetraploid yellows?
The stage was set by the use of one of those pesky triploid plants,
Phal Golden Sands ‘Canary.’ Golden Sands ‘Canary’ was out of a cross of a large
white and Phalaenopsis fasciata. The cross produced a lot of good-looking
triploid yellows, but the clone ‘Canary’ had the best color. Several years
of breeding attempts yielded nothing, and the plant was thought to be
sterile. Later, several species were bred to this plant, and these crosses
have produced many outstanding yellows: Liu Tuen-Shen (Golden Sands x
gigantea); Golden Amboin (Golden Sands x amboinensis); Goldiana (Golden
Sands x lueddemanniana); and more recently Golden Bells (Golden Sands x
Golden Amboin and Liu Tuen-Shen have both been very important on the way to
reds, but Golden Bells will also prove to be very important in the future.
These plants are of great importance because they are good tetraploid
yellows with strong color, good size and shape, and relatively high flower
Why are they tetraploids? It turns out Golden Sands ‘Canary’ is a rare plant
that gave up trying to split three chromosome sets, and lumped everything
together into a 3n ovule. It does not produce viable pollen. So, when
matched with pollen (n) from a diploid species, tetraploids (4n) resulted,
and the stage was set for producing good, tetraploid yellows and reds.
Another modern tetraploid yellow, Taipei Gold ‘Gold Star’, was a chance
tetraploid in an otherwise triploid grex. This plant will also continue to
play a part in the development of large red phalaenopsis.
Now it seemed all we needed was a good source of dark pinks or lavenders.
But crossing tetraploid yellows to tetraploid pinks produced sunset colors,
so this line of breeding was not pursued in the search for clear reds. With
time, and line breeding, this approach would have succeeded, and you will
see more of this type of breeding in the future.
In Taiwan, the crossing of a large white, P. Mount Kaala, with P. pulchra
produced an array of triploid plants with pink to lavender blotches and
spots. One of the plants produced had darker color but poor form. It
probably would not have been used for breeding in this country. A very
observant breeder in Taiwan, however, tried the plant and found it to be
fertile. This plant would be known as Paifang’s Queen ‘Brother’, a rare
chance-tetraploid resulting from an unreduced 2n pollen cell from the P,
Brother Orchids used this plant for breeding, and over time, found that by
matching it to plants such as Liu Tuen-Shen and Golden Amboin heavily
pigmented, fertile flowers were produced. Subsequent line breeding by
Brother Orchids and others has resulted in a wide selection of heavily
spotted and solid red flowers with good fertility and a size ranging from
7cm to about 9cm. To obtain larger sized flowers, we must now concentrate on
breeding this wealth of material to large, dark pinks to produce the final
result – 10cm reds. Some of this breeding is already accomplished with
crosses such as Brother Cortez Red showing the way. We are within a
generation or two of our goal. The plants now available allow any serious
breeder to produce a line of large, free-breeding, red phals. Some of those
commonly available that can be used to produce good tetraploid reds follow.
But beware of crosses such as Sogo Cock and Sogo Rose. Despite their awards
and visual appeal, these plants are also aneuploids.
A. Dean Stock is a founding member of IPA, a retired Cytogeneticist/Medical
Geneticist/Cancer Researcher, and owns Canyon Orchids in Kanab, Utah.
|Here are selected
grexes of known ploidy:
||TETRAPLOIDS USEFUL IN BREEDING:
Jenco Ruby Princess
Talung’s Red Fire
Brother Fancy Free
Brother Pico Mary
Brother Love Song
Taipei Gold ‘Gold Star’
Brother Yew ‘La Flora’
Fortune Buddha ‘Tinny’
Brother Pirate King
Brother Sally Taylor
Chingruey’s Sika Deer
Ching Her Goddess
Chingruey’s Blood Red Sun
Brother Jungle Cat
Sara Lee ‘Eye Dee’
Dou-dii Golden Princess
Brother Precious Stones
Brother Spots Way
Golden Buddha (some clones are near tetraploid)
Red Hot Imp
Cadiz Rock (some clones are near tetraploid)
Leucadia Lava Flow
Deventeriana ‘Treva’ (this is a near-tetraploid)
Ai Gold (near-tetraploid)
Rose Gold (near-tetraploid)
Ruth Tauscher (this is an estimate based on parentage – not counted)