Abstract Detail

Characteristics of nectar, nectaries, and nectar spurs

Roy, Rahul [1], Moreno, Nickolas [2], Kostanecki, Adam [3], Brockman, Stephen [4], Chiari, Ylenia [2], Bee, Mark [5], Hegeman, Adrian [6], Carter, Clay [7].

Convergent evolution of a novel blood-red nectar pigment in vertebrate-pollinated flowers.

Nesocodon mauritianus (Campanulaceae) produces a blood-red nectar that has been proposed to be attractive to geckos. Here we show that the red color of the nectar is derived from a novel alkaloid pigment, termed nesocodin. The first nectar produced is acidic and pale yellow in color, but over time it slowly becomes alkaline and subsequently takes on its characteristic red color. The production and stability of nesocodin is dependent on three enzymes secreted into the nectar: (1) a carbonic anhydrase creates an alkaline environment, (2) an aryl alcohol oxidase generates an aromatic aldehyde, a precursor to nesocodin, and (3) a ferritin-like catalase protects nesocodin from degradation by the hydrogen peroxide produced by the alcohol oxidase. Our findings demonstrate how these three enzymatic activities coordinate in nectar to allow for the condensation of a phenylpropanoid and an amino acid to form a novel pigment with a stable imine bond. We also identify nesocodin in the red nectar of the distantly related Jaltomata herrerae (bird pollinated) and provide evidence for convergent evolution of this trait. While the overall enzymatic activities required for red pigment formation in both Nesocodon and J. herrerae nectars are identical, the associated genes encoding the enzymes are not orthologous and, in the case of the aryl alcohol oxidase, even belong to different protein families. This work cumulatively identifies a novel, convergently evolved trait in two vertebrate-pollinated species, suggesting the red pigment is selectively favored and that there are a limited number of compounds that can be used to achieve this adaptation.

1 - UMN, Twin Cities, 720 BioSci Bldg, 1445 Gortner Ave, Saint Paul, MN, 55108, United States
2 - George Mason University, Biology
3 - University of Minnesota Twin Cities, Plant & Microbial Biology
4 - University of Minnesota Twin Cities, Horticultural Sciences
5 - University of Minnesota Twin Cities, Ecology, Evolution & Behavior
6 - University of Minnesota, Horticultural Sciences
7 - University of Minnesota Twin Cities, 1479 Gortner Ave, 140 Gortner Lab, Saint Paul, Minnesota, 55108, United States

Keywords:
nectar
nectaries
pollinator
alkaloid
phenylpropanoid
Flower color.

Presentation Type: Colloquium Presentations
Session: COL02, Characteristics of nectar, nectaries and nectar spurs
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 10:05 AM
Number: COL02002
Abstract ID:798
Candidate for Awards:None