mellicious: pink manicure (spring flowers)
[personal profile] mellicious
This is mostly for[personal profile] columbina- I'm putting in the full text because I'm not sure it's posted anywhere you can get to without a password. (I understand part of what it's saying....)

GENETICS: Color Convergence in Columbines

Laura M. Zahn

Anthocyanins are pigment molecules commonly found in red, blue, and purple flowers. Columbine flowers are imbued with anthocyanins, and this plant is known to have undergone a recent and rapid divergence, most likely as a result of strong selection by pollinators for floral traits such as color.

Using a phylogenetic framework, Whittall et al. have investigated the convergent loss--that is, the loss of the same trait across multiple evolutionary lineages--of anthocyanin biosynthesis in columbines, which has resulted in flowers that are yellow or white. They found six independent losses (four fixed and two polymorphic) and no gains of floral anthocyanins. Quantitating the anthocyanin precursors in three species without anthocyanin loss and eight species with loss demonstrated that the loss of anthocyanin correlated with a broad convergence in the reduced expression of genes that occur in the later stages of the biosynthetic pathway. Additionally, two of these genes are regulated by a single gene and demonstrated a correlated reduction of expression in five lineages, suggesting that the mutation causing anthocyanin loss is a regulatory component and not a structural one (enzyme). These data show that there is an evolutionary constraint on some of the genes in a nthocyanin biosynthesis, most likely because upstream intermediates are also useful in protecting plants against UV damage, insects, and pathogens. -- LMZ

Mol. Ecol. 15, 4645 (2006).

Date: 2006-12-22 07:59 pm (UTC)
From: [identity profile]

Columbines have lots of colors, but in recent decades their range of colors has increased dramatically. A large part of this is probably because either natural pollinators (bugs) or artificial pollinators (humans), or both, prefer them to have vivid and unusual colors.

Columbine genetic lines are complex due to frequent cross-pollination - not only do humans constantly cross-breed them in hopes of getting new colors, but columbines are self-seeding and cross readily with other variants of their species. Unusually, several different columbine genetic lines display a simultaneous loss of the ability to create the blue-red anthocyanin range. This manifests as yelloe or white flowers. Since a simultaneous occurrence like this across subspecies lines is very unusual, researchers have looked for some other reason why it might be desirable for the plant to lose this ability.

They found that a gene elsewhere in the plant's genetic structure is interfering with the genes for anthocyanin synthesis - that selecting for one trait reduces the incidence of the other trait. The researchers suspect that this other trait is one which protects the plant from physical and environmental damage. Therefore a colorless columbine may be a sturdier columbine.

Date: 2006-12-22 08:01 pm (UTC)
From: [identity profile]
Yellow. I kin spell good.

Now, how in heaven's name did you stumble across this in the first place? And isn't "Mol. Ecol." fun to say?

Date: 2006-12-22 08:28 pm (UTC)
From: [identity profile]
Science magazine. The library at work has subscriptions so we have full access. I get e-mails every week with abstracts. Most of it is kinda over my head but there's almost always some interesting stuff.


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