Were seedless bananas the result of selective breeding or a natural mutation?

[bascule]

Here's the statement at question in this thread: (original context)

 

The original seedless banana was not bred. It was a particular mutation discovered in the wild.

 

Were seedless bananas the result of selective breeding or a natural mutation first discovered in a wild banana plant?

[Sequence]

I think it was originally a mutation but then we grabbed onto it because it was good. Though it would make sense if it had been bred to be that way.

[Phi for All]

I've always heard that the Cavendish, the current most popular banana, was a result of selective breeding. The black lines still present in the middle used to hold seeds which were eventually bred out. It's popular for exportation because of this and a longer shelf-life rather than it's bland taste.

 

IIRC, there was a fungus that destroyed the last breed of popular banana back in the 50's and the Cavendish then became the export of choice.

[Aardvark]

IIRC, there was a fungus that destroyed the last breed of popular banana back in the 50's and the Cavendish then became the export of choice.

 

That breed of banana was the 'Gros Michel'. It wasn't completely wiped out and scientists are trying to cross it with the Cavendish to get a tastier and fungus resistant fruit.

[Phi for All]

That breed of banana was the 'Gros Michel'. It wasn't completely wiped out and scientists are trying to cross it with the Cavendish to get a tastier and fungus resistant fruit.

That would be great. I've never understood the Cavendish appeal with consumers. It's so bland compared to other varieties. I guess it says something about consumerism when we accept blah because blah is more economical.

 

I had a banana in Mexico once that was smaller than the Cavendish and had a bluish tint. The texture was creamy and the flavor was fantastic. I always wondered why American consumers didn't insist on more flavor over longer shelf life (surely cost couldn't be *that* much higher if it became really popular).

[Aardvark]

I had a banana in Mexico once that was smaller than the Cavendish and had a bluish tint. The texture was creamy and the flavor was fantastic.

 

I think most people don't realise that there is any choice in the matter, that a banana is just a banana.

 

Perhaps there is a gap in the market for high quality specialist bananas? I know i'd pay more for a blue Mexican banana! I think retailers could be missing a trick here, people are becoming more discerning and want more than just cheap food at the expense of blandness,(hope).

[bascule]

Bascule,

I do not quite understand why you feel the need to reply in such vehement terms. Surely, the origin of the humble banana is not something that requires this.

 

You're reading text. Whatever emotion you impart is your own interpretation.

 

My original source is a posting by Professor Anthony Trewavas on the Agbioview email magazine. You can find this email journal on google.

http://www.agbioworld.org

 

Sorry, I don't play "Here's a web site, now go dig for the information that proves me right." You have the burden of proof. You find it.

 

A seedless plant is, by definition, sterile. Any seedless mutants are doomed to instant death.

 

Yes, it is sterile. But it can be propogated using cuttings. And that is how it has spread world wide.

 

REALLY? Gee, let's go back to the post that started all of this:

 

The real reason the banana plant can't adapt is because it has been bread to be seedless and must reproduce with cuttings, eliminating its ability to adapt to the ravages of Panama disease.

 

I wonder where you learned that seedless bananas reproduce through cuttings. Perhaps... from me!

 

Cuttings are clones. You can't selectively breed seedless plants. They don't have seeds. They can't reproduce.

 

Wild bananas look like this:

 

 

Please tell me how they got to look like this:

 

 

Without selective breeding.

 

Come on. Then origin of the humble banana is not of Earth shattering import. Why have you reacted so strongly?

 

You're saying I'm wrong then pulled a big post out of your ass to describe why.

[SkepticLance]

Bascule.

The reason I did not previously enter this thread is that I think the issue is just too trivial to warrant a new thread. However, since you insist ...

 

I discovered from the Agbioview email newsletter in a discussion of GM work on bananas that the original seedless variety is a mutation, not bred. However, I did not keep the quote and I will not go back over perhaps 200 issues to find it, when the argument is so damn trivial.

 

However, I have been thinking about this. I cannot imagine how normal selective breeding could result in a seedless variety without some major genetic change (ie. a mutation). Normal selective breeding requires genetic variation, or else how can you select an advantageous variation. Genetic variation comes from sexual reproduction. Cuttings yield the equivalent of identical twins.

 

If you permit a flowering plant to reproduce sexually, you get seed formation. If no seeds, there was no sexual reproduction. No sexual reproduction means no genetic variation, and no progress in breeding. So to get selective breeding, sexual reproduction (hence seeds) are needed. No seeds means no sex which means no breeding. Hey.

 

Even to breed a strain that has only a smaller number of seeds is going to be difficult. To breed a strain (without a mutation) with no seeds appears to me to be impossible.

 

If you disagree with me, that is fine. However, let's end this silly discussion one way or the other.

[Aardvark]

I wonder where you learned that seedless bananas reproduce through cuttings. Perhaps... from me!

 

Cuttings are clones. You can't selectively breed seedless plants. They don't have seeds. They can't reproduce.

 

I don't want to step into a flame war here guys, but as a matter of interest seedless bananas are not just reproducd using cuttings.

 

Another technique is to hand pollinate domesticated bananas with pollen from 'wild' seeded bananas. By doing this, one in aproximately 10,000 bananas will contain a viable seed which can be used to grow a new hybrid banana plant.

 

This plant can then be backcrossed to produce a banana which doesn't have seeds.

 

It's very slow work, but it is a technique which is used. So you can see that seedless bananas can and are the product of selective breeding.

 

(and incidently, even just using cuttings there will occasionally be mutation and variation which can be selected for, sexual reproduction aids the process of selection but is not essential)

[SkepticLance]

Aardvark

Interesting post, and I am sure you are correct.

 

Doesn't alter the fact that you cannot breed a seedless banana from wild seeded varieties.

 

The fact that you get occasional mutations in cuttings does not alter this either.

[Aardvark]

Doesn't alter the fact that you cannot breed a seedless banana from wild seeded varieties.

 

Well, maybe, i'm not quite sure about that. Here's a link you might find interesting on the latest research into the paelobiology of the ancestoral banana http://www.inibap.org/news/ressources/File/phytoliths_fp.pdf

 

However, here is a brilliantly funny clip for you. The banana is 'the evolutionists greatest nightmare'. This is just too good, i almost believe it is a spoof, the banana as 'proof' of Gods benevolent creation.

 

Enjoy http://video.google.com/videoplay?docid=-5479410612081345878

[SkepticLance]

Thanks for the interesting reference, Aardvark.

 

Implication given is that the change to seedlessness (and probably greater size?) was due to polyploidy. As I understand it, this is a mutation rather than breeding.

[Mokele]

Ok, from how I understand it, bananas were selectively bred extensively when they *had* seeds for things like size, smaller seeds, flavor, etc.

 

Plant chromosome number is pretty malleable; they get by with losses, gains, even total duplications (the common strawberry is Octoploid, IIRC). But if a polyploid (diploid rather than haploid) pollen hits a normal ovary (haploid), you get a triploid, whose chromosomes can't segregate properly, and thus never makes seeds.

 

So, on one hand, there *was* selective breeding of bananas prior to seedlessness, but on the other a *common* meiosis error (well, common in plants) is likely what produced the seedless varieties. Honestly, with so many banana plants, I wouldn't be surprised if seedlessness cropped up dozens of times.

 

Mokele

[zyncod]

And (not knowing a whole lot about banana propagation), it is a mistake to think that sexual reproduction is the only way to selectively breed something. Bacteria can evolve antibiotic resistance (selective breeding) without any sexual reproduction. If you can reproduce a plant by cuttings, then you can do selective breeding without any sex - you just continue to pick the plants with the best bananas to propagate.

[SkepticLance]

zyncod

You are correct in theory. However, quantitatively, you are pushing a rather heavy barrow.

 

Bacteria develop new traits through mutations, and the most advantageous survive. Many hundreds of generations are required. To use this process with flowering plants such as bananas, but without sexual reproduction and the genetic variation associated with sexual reproduction, would take forever.

[zyncod]

Going back to the point of me not understanding a whole lot about banana propagation, though - if banana bunches were derived from single cells in meristematic tissue, asexual selection by cutting might actually be more efficient. Because you would have tens to hundreds of "generations" per banana plant. Without the backwards steps that sexual reproduction inherently introduces.

[SkepticLance]

zyncod.

Banana trees grow a 'leaflet' bunch at the base of the tree. To propogate, this is cut off and planted. Each generation requires times to grow a small tree.

[bascule]

And (not knowing a whole lot about banana propagation), it is a mistake to think that sexual reproduction is the only way to selectively breed something. Bacteria can evolve antibiotic resistance (selective breeding) without any sexual reproduction. If you can reproduce a plant by cuttings, then you can do selective breeding without any sex - you just continue to pick the plants with the best bananas to propagate.

 

zyncod, there is almost no variation between these plants, to the point that they are being wiped out by Panama disease because there is too little variation for any to have an immunity.