Abstract Detail

Comparative Genomics/Transcriptomics

Berardi, Andrea [1], Esfield, Korinna [1], Kuhlemeier, Cris [1].

Genetic mechanism of the transition to red floral color in Petunia.

Red flowers have long been associated with hummingbird pollination syndrome, and have arisen several times throughout the angiosperms. In the Solanaceae, red floral pigmentation is rare, with most flowers displaying purple, yellow, or white colors. The Petunia genus is no exception, and has even disabled the production of pelargonidin, the typically red anthocyanin pigment, through mutations in a key enzyme, thus constraining floral color to magenta to blue-purple hues. Despite these constraints, a single, pollinator-mediated shift in color hue to red has occurred in the endemic Petunia exserta. P. exserta floral color evolution is unique in three important ways: first that the typical Petunia R2R3-MYB anthocyanin activator, AN2, is nonfunctional in P. exserta, suggesting that the re-gain of pigmentation occurred through a different genetic mechanism than in sister species. Second, that P. exserta produces a red petal color although it is constrained to production of purple pigments, and third that it is pollinated by hummingbirds. We used bioinformatic, phylogenetic, biochemical, and molecular genetic techniques to evaluate this shift in floral color and validate involved genes. Here we describe the genetic and evolutionary mechanism of how co-option of an R2R3-MYB transcription factor previously associated with vein pigmentation restores entire petal color in P. exserta, and how subsequent mutations in biosynthetic genes and shifts in gene expression result in a visibly red color.

1 - University of Bern, Institute of Plant Sciences, Altenbergrain 21, Bern, BE, 3013, Switzerland

Keywords:
floral color
Anthocyanins
flavonoids
evolution.

Presentation Type: Oral Paper
Session: CG1, Functional & Comparative Genetics/Genomics I
Location: Virtual/Virtual
Date: Tuesday, July 28th, 2020
Time: 12:30 PM
Number: CG1001
Abstract ID:901
Candidate for Awards:None