B/c I'm obsessed with the maintenance of polymorphisms, the cross we used here is also polymorphic for leaf shape that I described last week.
This should allow ecological experiments looking at selection on leaf shape and anthocyanin loss in the same background.
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Former PhD student Georgia Henry collected and documented this rare, white-flowered Ipomoea hederacea.
We made a cross, and found the F1 was pigmented.
In the F2, Martin and Margaret showed that loss of pigmentation behaved like a single locus (not significantly different from 3:1 ratios).
Check out our new issue - including the Editor's Choice article by @jeromeburkiewicz.bsky.social et al! They show that despite phenotypic plasticity, flower morphology of the spotted jewelweed has evolved in urban habitats to better suit bumblebees, their main pollinators doi.org/10.1093/evle...
Why so rare, especially compared to flower color polymorphisms in the closely related Ipomoea purpurea?
(I think @gbaucom.bsky.social sent me these images from her field work).
First, purpurea is mixed mating, and white flowered alleles getting a transmission advantage from selfing.
Mark Rausher suggested an mRNA seq experiment with petals.
Expression of a single gene in the anthocyanin pathway, BZ1, was significantly different b/w purple & white flowered individuals.
BZ1 encodes UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT), the last step in the anthocyanin pathway.
How do you turn a purple flower white?
Another from lab, led by @damianmicroeco.bsky.social and Emily Glasgow, with big contributions from Martin Henry, Margaret Li, and Amanda Peake.
Mendelian Polymorphisms for the Win!
#evolbio #plantscience
Hederacea in contrast is highly selfing (>90%), suggesting that selfing won't provide a transmission advantage to white flowered individuals relative to purple.
We also hypothesize, based on the phenotypic and genetic rarity of this deletion, that selection acts directly against anthocyanin loss.
We next sequenced the genome of the white flowered individual, and compared to our recent collection of sequenced lines. These lines were all purple, and included the pigmented parent.
A coverage analysis indicates a deletion of half the BZ1 locus, including the start codon.
The deletion is absent in any of our other sequenced lines, and this is the only white-flowered individual my lab or I have observed in 25+ years working on Ipomoea hederacea. We have never seen this phenotype in > 750 lines we have collected and maintained in my lab.
Many thanks to the generations of Rausher alums-- Peter Tiffin, Rick Miller, Becky Zufall, Laura Mojonnier, the late Shu-mei Chang, Dave Des Marais, Robin Hopkins, Carrie Wessinger, Stacey Smith... the whole lot of you.
I never thought I'd work on the anthocyanin pathway, but here we are.
