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How does one identify a seed's species & variety, could it be done by some means of DNA or by use of a microscope? Say for example, I had a pumpkin seed, I knew that it was a "small sugar pumpkin" variety, but how would one scientifically identify it to know that it was infact a small sugar pumpkin as well as a pumpkin without going through the process of planting it. Is there some kind of indicator on a DNA level that shows "This is what I am?"

My knowledge regarding biology is extremely basic, but I am very interested in knowing the full process of how this would work.

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  • $\begingroup$ You sure, could identify plants by genotyping them. For many species, you can probably identify morphologically. For example, I am sure you are able to tell sunflower seed apart from flax seeds. Now, it will depend a bit about how accurate you want the identification to be. Sequencing would ultimately be most accurate (and most expensive) method. $\endgroup$ – Remi.b Jun 15 '18 at 16:19
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    $\begingroup$ @Remi.b: I disagree. The most accurate method would be to plant it and see what grows :-) I'm not sure sequencing would be that accurate, unless you have a pre-existing reference sequence for comparison. Even then, I doubt that all small sugar pumpkins are genetically identical. Could the gene(s) that differentiate a small sugar pumpkin from say an ordinary Halloween jack-o'-lantern one be reliably distinguished? $\endgroup$ – jamesqf Jun 15 '18 at 18:17
  • $\begingroup$ @jamesqf Ha ha that's right. Of course you;re right, identifying by genotyping will depends upon reference sequences. It will for sure be helpful to grouping related individuals in one's sample though. $\endgroup$ – Remi.b Jun 15 '18 at 18:24
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Yes, their name are "molecular marker". Every gene carrying a phenotype, quantitative or qualitative, is identified as an allele of every gene encoding for proteins. In order to identify a phenotype using just infos gained from DNA, you'll need a previous library made by these gene regions, were every polymorphism between them is associated with a phenotype. For example, a kind of marker used for this kind of work is SSR , or "Simple sequence repeats" : it is made by a simple sequence of DNA interspaced between two other region. The number of repeats of the internal sequence could be associated with a phenotype.

So, by a simple PCR you could amplify this regions:

SSR amplification protocol

And by a electrophoresis you could see how much repetitions are in your band, using just the molecular weight. Here is an example of SSR used for phenotype/genotype screening

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