Selfing????

[orchidman77]

So I've seen a lot of famous orchids "selfed" and the seedlings sold. I'm guessing that this means that the plant is crossed with itself with 2 flowers from the same plant.

But how is this supposed to work? Wouldn't the resulting seeds be sterile? And even if they aren't, aren't there some problems with crossing a plant with itself???

Thanks,
David

[johnblagg]

That depends on the plant a lot of plants including orchids can be self pollinated ...and the reverse also hold true all apple trees are not self fertile and not all orchids are not self fertile.This applies to many many plants not just orchids.

Seed from a plant that has been self pollinated are not necessarly sterile but often do have low germination rates it just depends on the plant you are crossing.Hybridization can either help or make this worse also.

We play roulette every time the genetic marble can jump all over.

[orchidman77]

okay......so just like everything else involving orchids, it's a "well, it depends......"

hooray. More confusion.

Thanks!
David

[King_of_orchid_growing:)]

Self fertilization is a method of sexual reproduction that some plants have utilized for continuing on the species.

This is a helpful strategy for many situations.

1. If there are not enough pollinators or if the pollinators went extinct, the plant can self pollinate in order to reproduce.

2. If there are not enough of the same species within a close distance, and the pollinator hasn't come by yet, but the flower is on it's way out...The plant will self pollinate in order to reproduce.

There might be other reasons that are very specific, but these are the two I can think up of right off the top of my head.

Sterility of the seeds is more common amongst hybrids. Many hybrids may grow to be strong vigorous plants, but some are sterile and are unable to reproduce. This is the reason why there are so many Phalaenopsis hybrids that are cloned. It's because many of them are sterile.

Speciation is not in large part due to hybridization. There are other factors involved in forming a species that are more reliable and play a much greater role.

I wouldn't refer to selfings as sterile. I would instead use terms like high viability and low viability.

Selfings may have a lower seed viability than outcrosses. And it obviously narrows the gene pool.

If there is less genetic variation, and if some drastic climatic event happened, for example. There's a very high probability that a very large population of the species can be destroyed if the genetics don't support the survival of the species in such a change, and this is the good case scenario. Worst case scenario, is the species goes extinct.

High genetic variation is important to a species' survival.

But as was mentioned, not every species of plant is self fertile. For these species, natural selection has ensured that they are able to continue the species via outcrossing and producing generations of plants with a high number of genetic diversity.

Being self incompatible has other more complicated factors involved, I will not cover this, because it's too much.

I suggest you take a botany class. It's very enlightening.

[Undergrounder]

Originally Posted by orchidman77

So I've seen a lot of famous orchids "selfed" and the seedlings sold. I'm guessing that this means that the plant is crossed with itself with 2 flowers from the same plant.

But how is this supposed to work? Wouldn't the resulting seeds be sterile? And even if they aren't, aren't there some problems with crossing a plant with itself???

It depends what genus (some are self-sterile), and then even within genus, some species are more amenable to self-fertilisation that others, and then some hybrids are sterile anyway because of poor breeding decisions.

But in Phalaenopsis, which is what i know better, self-sterility is rare. Most of the popular hybrids and species are definitely happy to produce seed by selfing, and only particular crosses that are completely sterile (or very difficult to breed) will be self-sterile as well.

The main 'problem' with crossing a plant with itself is there are a lot of recessive genes expressed in the seedlings, which can lead to poor growth and other problems, known as 'Inbreeding depression'.

But on the other hand, the traits of the parent plant have a higher chance of coming through in the seedlings. For instance if you have an amazing, rare Blue phalaenopsis, (where the blue trait is highly recessive) then any kind of out-cross to something without the blue gene (say, pink), will probably lead to seedlings that are almost totally pink. But if you self your Blue phalaenopsis, then that recessive gene will probably be expressed in a much higher proportion of the seedlings.

That's why the famous orchids are selfed - it locks in those particular award-winning traits and makes the resulting seedlings more homozygous (similar to eachother).

[orchidman77]

wow guys. I feel so much smarter already!!!! Okay, for some reason I thought it couldn't be done, but I guess i was wrong! I ask because i (eventually) want to do some crosses and always wondered why so many seedlings were " blahblahblah x self".

David

[Erce]

good reading - i wonder the same thing many times

[King_of_orchid_growing:)]

Originally Posted by Undergrounder

It depends what genus (some are self-sterile), and then even within genus, some species are more amenable to self-fertilisation that others, and then some hybrids are sterile anyway because of poor breeding decisions.

But in Phalaenopsis, which is what i know better, self-sterility is rare. Most of the popular hybrids and species are definitely happy to produce seed by selfing, and only particular crosses that are completely sterile (or very difficult to breed) will be self-sterile as well.

The main 'problem' with crossing a plant with itself is there are a lot of recessive genes expressed in the seedlings, which can lead to poor growth and other problems, known as 'Inbreeding depression'.

But on the other hand, the traits of the parent plant have a higher chance of coming through in the seedlings. For instance if you have an amazing, rare Blue phalaenopsis, (where the blue trait is highly recessive) then any kind of out-cross to something without the blue gene (say, pink), will probably lead to seedlings that are almost totally pink. But if you self your Blue phalaenopsis, then that recessive gene will probably be expressed in a much higher proportion of the seedlings.

That's why the famous orchids are selfed - it locks in those particular award-winning traits and makes the resulting seedlings more homozygous (similar to eachother).

The principle described here about bad recessive genes showing up in repeated selfings and sib crosses, thus causing deformities is one of the biggest problems I have as someone who wants to breed species orchids.

It appears that there are some species that have a very limited amount of genetic diversity in the hobby because only a small amount of specimens were collected and a smaller amount survived. And this is what breeders have got to work with.

There are too many factors that contribute to this problem. One of them are the crappy CITES laws that are making it harder and harder to import plants from other countries, even flasks.

Something seriously needs to be done.

[littlefrog]

The gene pool is very limited for some species. Some might rely on only a single founder plant. There are lots of reasons for this, the two main ones are probably CITES as mentioned (it can be difficult to get new plants into cultivation) and possibly more important, most people do not breed their orchids. So, very nice species may be in cultivation, but are never used in breeding so their genes do not get passed on.

Inbreeding is less of a problem for plants than animals. But not for the reason you think. Humans are generally considered less expendable than plants. Genetically inferior humans are usually not culled (for obvious reasons), but you get a lot of plants out of a cross and you should certainly cull the worst out. As a breeder you should expect that 90% of your efforts will be total garbage, and feel very lucky if you get a better percentage. A lot of plants won't even make it out of flask, if they have messed up genetics they won't grow very well. A lot of the remaining plants will be inferior. A very few of the plants will be superior, and those are the ones you breed with.

An old adage, you judge an orchid breeder by the size of his compost pile, not the number of plants in the greenhouse. Inferior plants should be destroyed, not given away or sold. The goals of your breeding program may vary, but when I screen plants (rarely, I don't do much hybridizing lately) I insist on vigor and ease of bloom as the primary factors. Flower quality is third. No point having a beautiful flower on a plant that won't grow. Anything that isn't vigorous and easy to bloom gets thrown away. Of the remainder, only the very best flowers are used for breeding, of course. That doesn't leave much.

For species, you get better odds. Most straight species crosses (selfings or outcrosses) give pretty good results. Most of the offspring will be satisfactory, and if the cross takes at all you usually have pretty high viability. Most primary hybrids (crosses between two species) give pretty predictable results. When you get farther away than that (selfing or crossing complex hybrids), all bets are off and you'd better have your pitchfork ready.

[Royal]

Originally Posted by littlefrog

An old adage, you judge an orchid breeder by the size of his compost pile, not the number of plants in the greenhouse. Inferior plants should be destroyed, not given away or sold. The goals of your breeding program may vary, but when I screen plants (rarely, I don't do much hybridizing lately) I insist on vigor and ease of bloom as the primary factors. Flower quality is third. No point having a beautiful flower on a plant that won't grow. Anything that isn't vigorous and easy to bloom gets thrown away. Of the remainder, only the very best flowers are used for breeding, of course. That doesn't leave much.

That's a funny saying, I've not heard that one. Wise words.