Abstract Detail

Functional Genetics/Genomics

Srinidhi, Holalu [1], Patterson, Erin [2], Grace, Johnson [1], Wei, Lan [3], Colicchio, Jack M [4], Blackman, Benjamin [5].

The genetics of ultraviolet nectar guide pattern diversity in the common monkeyflower.

Floral pigmentation patterns attract and guide insect pollinators to ensure successful pollen transfer. Anthocyanins and flavonols confer red and ultraviolet (UV) floral pigments, respectively, and flavonol pigment patterns are invisible to the human eye but interpretable as landing strips to pollinators. Although enzymes and transcription factors involved in floral pigment synthesis are known, our knowledge of the factors that regulate the developmental patterning of flavanols and govern their pattern evolution remains limited. In the common monkeyflower Mimulus guttatus (syn. Eyrthranthe guttata), the ventral lobe of the corolla develops a UV absorptive area that is also dappled by red spots. In population surveys, we find ample polymorphism in UV pigment patterns, and pollinator choice experiments demonstrate the importance of UV patterning for pollinator attraction. We performed QTL mapping in a cross between a “runway” morph (entire ventral lobe is UV pigmented) and a “bullseye” morph (only the upper lobe sector is UV pigmented). Bulked segregant analysis revealed an oligenic genetic architecture, and one of the four QTL regions contains two tandem copies of the R2R3-MYB transcription factor LIGHT AREAS1 (LAR1), a known promoter of flavonol production. Both copies show sector-specific differences in transcript abundance. We also fine mapped a rare pleiotropic variant that both affects UV pigment intensity and forms red rings instead of solid spots to a homolog of FLAVONOL SYNTHASE (FLS). Consistent with the variant’s reduced FLS expression, RNAi-mediated knockdown of FLS recapitulated both the reduced UV pigmentation and red rings. We introduced targeted mutations in FLS and both LAR1-like genes by multiplexed CRISPR/Cas9 in a runway morph background. LAR1-like double mutants exhibit striking UV pigment reduction in the upper but not lower petal sector and also have anthocyanin spots of altered hue. Our results implicate all three genes in flavonol production and patterning variation in M. guttatus and reveal novel interactions between red and UV floral pigmentation.

Related Links:
Blackman Lab Website

1 - UC Berkeley, Plant and Microbial Biology
2 - University Of Massachusetts, Plant Biology Graduate Program, 204C French Hall, 230 Stockbridge Rd, Amherst, MA, 01003, United States
3 - University of California, Berkeley, USA
4 - UC Berkeley, Department of Plant and Microbial Biology
5 - University Of California, Berkeley, Plant And Microbial Biology, 111 Koshland Hall #3102, Berkeley, CA, 94720, United States

Keywords:
floral traits
pigmentation
Mimulus
QTL mapping
Gene editing
CRISPR/Cas9
flavonols
anthocyanins
natural variation
evodevo.

Presentation Type: Oral Paper
Session: FG, Functional Genetics and Genomics
Location: /
Date: Monday, July 19th, 2021
Time: 11:00 AM(EDT)
Number: FG005
Abstract ID:870
Candidate for Awards:None