Seedless Watermelon Genetics! – Bite Sci-zed
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Seedless Watermelon Genetics! – Bite Sci-zed

Few things scream
summertime quite like a juicy slice
of watermelon. But these days it’s
nearly impossible to find a slice
in the store that has those characteristic
black spots of seed spitting contests of days past. In fact, when I went
looking for a watermelon, I could not find one with
seeds in my local store. But the story behind how you
get these seedless watermelons is actually a pretty
cool genetic trick. So let’s talk about the
basics of watermelon genetics. Unlike humans, which have
23 pairs of chromosomes, watermelons only have 11. But like humans,
watermelons are diploid. This means that
they have one copy of each chromosome
from their mother and one copy of each
chromosome from their father. During normal cell division,
each cell in your body copies its set of chromosomes and
passes an identical set onto each progeny cell. This is done in a process
known as mitosis, which I talked about in this video. However, in order
for you to only get one copy of each chromosome
from your mother and one from your father, the
cells in their body, which go on to create sperm
and eggs, their germ cells, have to undergo a slightly
different process known as meiosis in which
a diploid cell splits into two haploid daughter
cells, each of which contains only one copy
of each chromosome. That way when the egg
from your mother and sperm from your father
combine, they’re each contributing just one
copy of each chromosome. So that you have
two copies of each and are once again diploid. So now back to watermelon seeds. Watermelon seeds form
their hard, black shell coat, or testa, after
successful fertilization. So to prevent this and
get seedless watermelons, farmers mess with the
number of chromosomes that each watermelon
has, therefore preventing successful fertilization
and preventing correct seed formation. How? Let’s start with the
female parent plant. Young watermelon
seedlings are treated with a chemical
called Colchicine, which prevents proper
splitting of the chromosomes during mitosis and results in
plants that are tetraploid, containing four copies
of each chromosome. When these tetraploid
plants undergo meiosis, instead of creating a haploid
daughter cell with only one copy of each chromosome,
they actually create a diploid daughter
cell with two copies of each chromosome. If you cross this
with haploid pollen from a normal watermelon
plant, you wind up with triploid waterman progeny. And watermelons do not
like having three copies of each chromosome. These three copies
of each chromosome can’t properly separate
during meiosis, leading to unsuccessful
fertilization, leading to watermelon
plants that can’t properly produce seeds. Now, I think that’s a
pretty tasty genetic trick. Go forth. Do science.

51 thoughts on “Seedless Watermelon Genetics! – Bite Sci-zed

  1. How do you make a seedless watermelon? I explain in the latest Bite Sci-zed! Seedless Watermelon Genetics! – Bite Sci-zed

  2. The story behind seedless watermelons is one of the triumph of style over substance. Seedless watermelons are practically tasteless, like seedless grapes. It's the sort of thing that managers like to do in order to satisfy some deep need for spreading crap for public consumption. And of course we as consumers have no choice in the matter.

  3. Those "seedless" watermelons are for me even worse since I take out every seed and it just makes it even harder when the seeds are small and soft.
    Do you think there is at least a theoretical way to modify the the genes of a watermelon in such a way that it forms all the seeds in the middle like a melon, without affecting its other characteristics?

  4. Pretty disgusting how humans deprive nature of its reproductive capability, just because of money, huh?
    Well, let's hope it doesn't backfire and every food dies out within one crop cycle, because all plants are either producing dysfunctional seeds or no seeds at all. Although, it would be funny to see the infestation of humans starve and hand the plant back over to evolution. Still, the collateral damage to other species which still (unlike humans) have the chance to evolve into an intelligent life form would be pretty high in that case…

  5. Yesterday, I went to the grocery store and saw that they had seedless watermelon and I was wondering how they made the watermelon seedless, and your video explained it wonderfully.

  6. Thanks for this episode.  I honestly dislike the genetically modified seedless watermelons.  I'm very picky on this fruit, because the flavor dies or is bland about 70% of the time when I try having one.  What science has led to bland watermelons?  Not talking about how old or aged, but there has gotta be a cause for this.

  7. I thought that in meiosis each diploid cell split into FOUR haploid cells, through the crossing of genes, followed by a split and duplication similar to mitosis, forming two diploid cells with shuffled genetic material, then both splitting in half without duplicating to form the four haploid cells.

  8. So I'm guessing that this is not done to all watermelon plants as you do need to produce viable seeds to plant the watermelon in the first place!!

  9. Awesome video Alex. The braces are great also! Pretty glad your back to doing videos I can just imagine what your schedule looks like. Keep up the good work!

  10. I dont know what it is but in your old videos you seemed to be more natural with the camera and had more life in you. 

  11. Hmm, so what happens if two tetraploid watermelons breed? Just more tetraploid melons? Do tetraploid watermelons have any distinct features? 
    Also, can you double up  further? Have an octoploid, or even sedecploid? Could they have distinct features?

  12. Seedless or not, watermelons don't really taste like much, so ya'll can stop griping about these ones tasting worse than the ones with black seeds. They both taste like mildly sweetened water-soaked cellulose. 😛

  13. Great video once more. It's curious how people are still scared of what we can do to produce different thing, just take a look to the comment.

  14. I'd like to have seedless stone fruit (cherries, plums, etc.) as well as mangoes, apples, pears and others.  Will horticultural technologists accomplish this?

  15. If this happened in a human they would be retarded. We are eating retarded watermelon? Just think if they spray this out of a plane over a large population, you'd get eugenics.

  16. so it is messing with genetics! Thoes jerks, I don't want to eat that, there not even sweet and red on the inside

  17. Mary 1:3! King: King-King-King! 1: American (South-Latin-North); 2: RBS (Russia British Scandinavia); 3: EUROPE AFRICA; 4: AIOP (Arab India Oceania Pacific). American: RBS+EUAF-AIOP!

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