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varialectio t1_j66fh13 wrote

Like other seedless things, you cross two varieties that you know will produce seedless progeny in the first generation (F1 hybrids). You obviously can't produce offspring from them so if you want to breed more plants you have to go back to the original parents each time.

You can always take cuttings and propagate your seedless variety as clones too.

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wildfire393 t1_j66mz77 wrote

I'm not sure this works for grapes, but I know the method they use for watermelons is quite clever.

Sex cells, like sperm and eggs, are made by evenly splitting chromosomes. Humans, for instance, have 46 chromosomes in 23 pairs, and each pair splits off so the sex cell has 23 chromosomes. Those 23 mix with the 23 from another person's sex cells and you end up with the 46 chromosomes that will make a new person.

But if you have an uneven number of chromosomes, you can't split them, and will therefore be sterile and incapable of producing sex cells. This is why mules are (generally) infertile - horses and donkeys have different numbers of chromosomes, so while they can reproduce and make a mule, that mule has an odd number of chromosomes and is sterile.

So for watermelons, what they've done is taken a strain and engineered it to have doubled chromosomes. Rather than have 30, for instance (I don't recall the exact number of chromosomes they have but it's not strictly relevant), it has 60, with every chromosome just duplicated. So the genetic makeup is the same and the fruit is exactly the same. They can breed the normal watermelons with other normal watermelons and the doubled watermelons with other doubled watermelons, and either of those results in seeded fruit, which they can use to keep growing the next generation.

But when they cross the two, the resulting melon has an odd number of chromosomes (in the example above it'd have 15 from one parent and 30 from the other for 45 total). It's still got the usual genetic makeup and grows as normal, but as it can't form sex cells, it doesn't develop seeds.

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dan_the_man48 t1_j66f7br wrote

Selective breeding, like most things grown today you take what properties of the fruit or vegetable that you like and keep growing that kind untill you end up with seedless bananas or seedless grapes

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Exact-Vast3018 OP t1_j66fgni wrote

Ok i had a feeling they were manipulated the same way bananas were, i always thought they were natural.

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srcarruth t1_j66gzg0 wrote

Maybe they are, all navel oranges are related to a single mutant tree. Made from cuttings and endlessly propagated. People think science is magic too often.

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ISBN39393242 t1_j66ill2 wrote

>People think science is magic too often.

you can say that again.

peoples’ expectations of science and medicine are so wild. and the more uninformed, the more they expect. when you’re an actual scientist you realize it’s a mix of working banging your head against the wall for the most tiny incremental gain in knowledge (this is the vast majority of science) + the rare landmark finding, which usually gets milked for its every potential application across all fields of science.

but people really sit back and think scientists could just do whatever they wanted if they felt like it (and therefore the reason e.g. aids has no cure is because they don’t care enough, as opposed to the fact that it’s actually not possible).

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oblivious_fireball t1_j66iy43 wrote

usually seedless plants don't evolve from seed-bearing ones very often, simply because the plant then needs to reproduce through other means like offshoots or broken off pieces rerooting without human help, and most die out faster than these methods occur or can't spread away from the parent easily. One of the only natural cases i can think of is Devil's Ivy which has a genetic defect that prevents it from producing its flowers and therefore seeds. But its a rapidly growing vine that produces a lot of rooting hormone, so it pretty readily spreads and any broken pieces easily root down into new plants.

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