Love notes of genetics and physiology for Valentine’s Day

A St. Valentine meme compliments of my "friend" the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.
A St. Valentine meme compliments of my “friend” the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.

Ahhh….’Tis the time of year when we celebrate romantic love in homage to a 3rd Century priest who came up a head short for performing unsanctioned Christian weddings.  (It is also of note that St. Valentine, or Valentinius as his friends called him, is the patron saint of bee keepers but, strangely, not of birds, flowers, or trees).

In celebration, many suitors, partners, spouses, fling-seekers, and woo-wishers will flock to florists, grocery floral counters, and even gas stations to purchase flowers, namely roses, that have likewise been beheaded.

Those roses, with all of their tightly wound petals, look nothing wild-type roses. Modern roses are the product of many centuries of breeding that started independently in China and the Mediterranean region.

So if the wild-type rose has a single row of five petals, how do breeders get all of those extra petals?  They can just come from nowhere, you know.

The simple answer is that tissue that turns into stamens in the wild-type flower are converted to petal tissue.  While early (and even contemporary) plant breeders may not understand the mechanism responsible for the doubling (gene expression), research is showing that the same gene is responsible for the doubling in both the Chinese and Mediterranean set of species/subspecies.

In a nutshell, what happens is that the different regions of the flower – sepals, petals, stamens, carpel – develop in response to the expression of a set of genes.  It isn’t just the genes acting alone, though; it is their interaction in the tissues that makes the difference.  These genes are grouped by the floral part they affect and are grouped as A-Function, B-Function, C-Function, and E-Function.

If you want to learn a whole lot more about it than I can ‘splain (it has been a few years since my last plant physiology class), this paper thoroughly explains the gene expression and evolution of the flower.  Their figure depicting the flower model is informative, yet simple.  I’ve included it (and its accompanying caption) below.

The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function
The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function.  http://www.pnas.org/content/107/52/22570

 

In the paper “Tinkering with the C-Function: A Molecular Frame for the Selection of Double Flowers in Cultivated Roses” researchers show that in lines from both regions of the world produced double flowers as a result in a reduction of expression of the C-Function gene AGAMOUS (RhAG) leads to double flowers.  In Arabidopsis (every plant lab bench jockey’s favorite model plant), this reduction shifts expression of the A-Function genes toward the center of the plant, turning stamens into petals and carpels into sepals.

Now, one question I get from time to time is “why don’t these roses smell like the old-fashioned roses?”  One answer is that as we breed for looks, we are breeding out genes responsible for scent oil production.  So Shakespeare was actually wrong when he said that “a rose by any other name would smell as sweet.”  That isn’t true these days.

So, I wish you a perfectly lovely Valentine’s Day, no matter how you celebrate. Just remember to whisper sweet nothings of floral gene expressions in your sweetheart’s ear.  And remember to stop and smell the roses – if it is a variety that has a decent scent.

Cool plant of the day: Canary Bellflower

I’m such a plant nerd that a few years ago I actually decided to get Canarina canariensis, the Canary Bellflower, for no other reason than that it is one of the very few members of  the campanula family that has red-orange flowers instead of the usual purple-blue ones.

canarina 2
Canarina canariensis
A Platycodon showing much more typical coloration for this family
A Platycodon showing much more typical coloration for this family

Okay. Maybe that isn’t the most normal reason to add a plant to one’s garden, but I am VERY happy I did.

Canarina canariensis
Canarina canariensis

That color!

I’ll admit, it isn’t a plant that is particularly well adapted to life here in Michigan… as the latin name suggests (twice!) it is native to the Canary Islands off the West coast of Africa, where the climate is consistently dry, fairly cool, but never freezes. The summers are extremely dry, with a short rainy season in the winter. And the Canary bellflower has adapted to that by dying back to the thick fleshy roots in the summer, and then sending up the long trailing stems and flowers in the winter when the rains come.

That isn’t ideal for growing here in Michigan, but I’ve found I can get it to grow here pretty easily, actually. It is growing and blooming like crazy right now, and once it gets cold, I’ll move it inside, and let it dry out. As the soil dries, the plant goes dormant, so it can sit there patiently until spring and more settled weather when I can water and set it off into growth again. It works, and though it is a bit more work than most of the other plants I grow, it is worth it. I like looking at the lovely flowers, and speculating about the unique evolutionary path that caused this one genus to develop orange flowers while the rest of the family largely stuck with the tried-and-true purple.

Neon for your garden

Was wandering through Target on Monday for the first time in months.

Helloooo!? The 80’s called and wants its neon crap back.

Didn’t care for it then and certainly don’t care for it now. Though there is the increased safety factor of being highly visible at all times, whether in sunglasses or underwear.

But never mind my lack of style.

It made me think about a few plants that, if the light is right, certainly display that glowing, saturated color, found in the “Astro-Brite” pack of copy paper usually reserved for yard sales and such.

Close to dusk, the Kniphofia uvaria ‘Echo Mango’ in our garden stands out from 100 yards away.  Bred and selected by Richard Saul of Atlanta’s ItSaul Plants Inc., it is one tough perennial, taking heat and humidity with aplomb.

My experience has been one big early summer flush of blooms, with some significant reblooming until frost.  Best in full sun, it’s also drought tolerant and cold hardy to USDA Zone 5. It doesn’t get whopping huge like some other Kniphofia do – stays a nice manageble size, topping out at 3′ to 4′ tall.  ‘Echo Mango’ (or any other Red Hot Poker) adds a terrific bit of vertical interest to an otherwise mound-y mixed border.  Best with fellow warm colors. Pink, not so much.


‘Echo Mango’ = glowsticks!
Achillea ‘Paprika’ doesn’t go so well with it.  Mental note to relocate it in fall.


You can almost hear the sound of space lasers…
Eeee-yoooooo-eeeee-yoooooo…or maybe that’s just me.

 

 

Sheep-eating flowers?!

I was planning to follow up on Jeff’s phosphorus post with a bit more “phun with phosphorous.” However, I was completely derailed by Ray Eckhart’s message and link left for me on our GP facebook page with this headline:

RHS ‘sheep-eating’ plant about to bloom in Surrey

“The Royal Horticultural Society (RHS) at Wisley said the Puya
chilensis
, a native of Chile, would bloom in the next few days and last
about a week.

In the Andes it uses its sharp spines to snare and trap sheep and other animals, which slowly starve to death.”

“The animals then decay at the base of the plant, acting as a fertiliser.”

[Dear BBC News: “Snare” and “Eat” are not really interchangeable]

How…have I not heard of this before.

I’ve posted previously on my Puya fixation. I asked readers to bet on how long it would take for me to kill my wee Puya bertoniana, mail-ordered from Annie’s Annuals.  I am happy to report that it made through the winter (greenhouse) and is now sunning itself on our deck.

Now this really ups the ante – it captures sheep!  Maybe P. bertoniana isn’t as robust as P. chilensis though. Perhaps…a vole or rabbit?

Solution to Friday’s flower fuddlement

Ed and Gayle correctly pointed out that short day plants (those that bloom in the spring or the fall) can sometimes do both.  The asters probably experienced some transplant shock in the fall, which would have suspended floral bud development.  This phenomenon could also be due to mild winter conditions (as Ed and Gayle also mentioned), which could have spared flower buds normally killed by freezing temperatures.

In any case, as spring daylengths approached those found in the fall, flower development continued and voila!  Asters in the spring!  Likewise, there are a number of spring bloomers that sometimes have a second (usually reduced) floral display in the fall.

Thanks again to Ginny for sharing her photographs and information!

Floral fuddlement

Gardeners love asters as part of their autumn floral palette.  Yet these native asters are blooming now – in the spring!

These specimens were purchased last summer and planted in the fall in Florida. Why might they be blooming out of season?

Reader Ginny Stibolt contributed today’s puzzle.  If you’d like to be a guest inquisitor on our blog, send photos and explanatory text to Linda Chalker-Scott.

Are Pretty Flowers Useful?

Yesterday I had the opportunity to listen to Marla Spivak, a very highly regarded bee scientist, talk about how bees defend themselves from disease.  Very interesting stuff.  I took a lot of information away from the talk, two bits of which I want to share with you.

The first is a vocabulary word — propolis – go ahead, google it (I don’t think too much inappropriate stuff will pop up) – it’s an antimicrobial “ointment” which bees create from stuff like the resins on tree buds.

The second is that the number of bee colonies is the US has been going down in the US since 1945 for a number of reasons.  One of the most important of which is the fact that we like to kill flowers, such as dandelions and clover, which bees like, and then we plant crappy flowers – at least as far as the bees are concerned.  The whole crappy flower thing isn’t something that I’d spent much time thinking about, so it was kind of an ah-ha moment for me.

Here’s how it works.  People tend to like double flowers.  Double flowers usually occur because the male parts of the flowers – the parts which normally contain pollen – instead develop into petals.  It’s a mutation – very pretty – but it inhibits the flower from reproducing itself through seed and it certainly isn’t great for bees who rely on pollen for food.  So when we plant our gardens we are removing plants that bees may love because we consider them weeds.  Then we replace these flowers with what amounts to plastic fruit.  My opinion – this is probably more significant to the lives of both honey bees and native bees than whether we plant natives or exotics.

So let your yard go wild!  The bees will thank you.