Genetic differences in scent

[TZ-Someplace]

Way back when, I took two blooming B. nodosa to an OS meeting. One was the skinny typical form and the other had big flowers and short wide leaves. I stood up in front of everyone and said, "This skinny one fills the house with wonderful fragrance but it's really too bad about this one with the big flowers. It has no scent what so ever."

Well, it turns out I was the only person in the whole room who couldn't smell the fragrating blooms of that wide leaved plant that night. I'm wondering if that plant was B. grandiflora and there is a chemical difference between the two species of if there can be a difference within the same species.

Anything like that happen to any of you?

[Ray]

Plants are individuals, too, so I can think of no reason why different ones might not have difference fragrances, especially considering the complexity of such chemistry.

Plus, as you pointed out - you - were the only one who couldn’t detect it, pointing out different genetically-imposed sensitivities, too.

[Louis_W]

Interesting! Sounds like you may not be able to smell the compound for whatever reason! Hasn't happened to me yet!

Did they smell the same to the people who could actually smell them? Im not very experienced in the matter but it seems like orchids can be identified fairly accuratley by their smell. I recently read an article by Chadwick and sons that was talking about early botanists arguing about taxonomy based on samples and physical structures while horticulturalists differentiated species by growth habit and fragrance. Its about cattleya but here's a quote:

"At times, the artificial rules of botany severely inhibit our ability to evaluate nature, and the large-flowered Cattleya species are a good example of this. It was unnecessary to drag these species through 100 years of botanical uncertainty, when the people who grew them in the mid-1800s had already answered all the questions on how they were different, and why they should be separate species.

FRAGRANCE We have not yet found a way to describe fragrances with simple words, but if you grow the large-flowered Cattleya species, you need no other characteristic to identify them. They all have lovely, distinct fragrances that are unique to each species...."

Here is a link to the whole article:

Large-Flowered Cattleya Species

A that was to say that perhaps they are two different species??

[TZ-Someplace]

I don't recall anyone saying the two plants smelled different.

It reminds me of some of the Mendelian single gene tests from old freshman biology labs such as hitch hiker's thumb, ear lobes, and there is a chemical that can or can't be tasted. Smelling strong asparagus scent when it passes through the body is another but I don't know it that is single gene.

[Ray]

Originally Posted by TZ-Someplace

I don't recall anyone saying the two plants smelled different.

Are you suggesting that “fills the house with a wonderful fragrance” and “no scent whatsoever” does not suggest “different”? 🤔

[Dimples]

A few months ago I bought a new gentle “everyday” exfoliating lotion. I gave it a sniff in the store and it smelled like nothing, like the most mild unscented lotion ever. Took it home and applied it while my SO was around and he asked “WTH is that?!”. Turns out it smells absolutely terrible to him and is strongly scented when he’s smelling it.

I looked up reviews and it seems some people smell nothing and others find this lotion revolting. No idea what ingredient or combination of ingredients is causing this but it’s completely possible for you to be genetically incapable of smelling the one orchid.

[Grim Tuesday]

Finally, something on this forum I'm qualified to answer! Yes, genetic differences in smell are highly possible. As Ray pointed out, there are two obvious genetic differences here: the one in the plant, and the one in your nose!

Broadly, the way smell works is that there are about 400 unique types of neurons (together they are the olfactory sensory neurons) way up in the nose. Each one expresses a protein that causes it to become more active when a certain compound bind to it. Some compounds may bind to multiple olfactory sensory neurons, and some (most) smells are made up of multiple compounds. Likewise, different compounds may bind to the same set of olfactory sensory neurons (rubbing alcohol and vodka smell about the same but are different compounds).

What we perceive as a "smell" is the population code (i.e. on, off, off, on, on, on, on...) for each of the types of neurons. The way a population code leads to a certain odor percept is not currently well understood. That is to say, we know it happens but if you gave someone (or even someone with a state-of-the-art algorithm) a olfactory population code, they could not predict how it is going to smell. This is in contrast to the visual system where we have a very good idea for how light produces codes in the retina that lead to vision.

Now why might you be unable to smell something that others can smell? Individual differences re very common in the genes that code for the proteins that determine the selectivity (which compounds they bind to) of olfactory sensory neurons. You are probably missing one (or it is slightly mutated so it is selective for something else) that binds to the compound that the plant produces. I am a neuroscientist, not a horticulturist so I can't speak to what happened in the plant's genes to cause it to produce a different odor than the other one but it seems like just another result of sexual reproduction.

By the way, I totally understand how this feels. Roses have no scent to me. It really seems limited to roses, I can smell every other flower as well as anyone else including beach roses. But classic roses, rose water and rose perfume I cannot smell. Or if I can, I am getting the other scents of them (like vegetal, sharp, soapy ones).

[Diane56Victor]

Wouldn't it be wonderful if fragrant orchids were given to perfume 'noses' to assess and describe their fragrance.