Abstract Detail

Hybrids and Hybridization

McCarthy, Elizabeth [1], Landis, Jacob [2], Kurti, Amelda [3], Lawhorn, Amber [3], LITT, AMY [4].

Homeolog expression bias in floral color evolution in natural and synthetic Nicotiana tabacum allopolyploids.

The evolution of angiosperms has been marked by the influence of both polyploidy, having multiple sets of chromosomes, and hybridization, possessing genomes from multiple species. Allopolyploids, the product of both hybridization and polyploidy, display genomic, expression, and phenotypic differences compared to their diploid progenitors. Many studies have documented these differences, but few link changes in expression to changes in phenotype. Here, we use allotetraploid Nicotiana tabacum, which originated ~0.6 million years ago, along with synthetic lines created using the same progenitor species, N. sylvestris and N. tomentosiformis, to determine whether differences in homeolog expression bias drive changes in floral color among accessions. Our N. tabacum accessions and their synthetic counterparts vary in floral color between light pink and dark pink. These floral color changes result from differences in the concentration of cyanidin, a magenta pigment, and flavonols, pigments which are colorless to humans. Cyanidin and flavonols are produced via the flavonoid biosynthetic pathway, a branched pathway that yields many different pigments. The structural and regulatory genes of this pathway have been well-characterized, which allows for investigation into the role of homeolog expression bias in gene network evolution and in changes in phenotype among closely related allopolyploids. We combine Illumina transcriptome data with long read, full length transcripts from Oxford Nanopore technology from the progenitor species to accurately measure homeolog expression ratios of the genes involved in the flavonoid biosynthetic pathway in natural and synthetic N. tabacum accessions and compare them with the expression ratios between their diploid progenitor species. We hypothesize that the magnitude of homeolog expression bias will increase with allopolyploid age and that changes in homeolog expression bias will correlate with changes in floral color among related allopolyploids that share the same diploid progenitors. Our results will provide insight into whether homeolog expression bias plays a role in phenotypic evolution among closely related allopolyploids.

1 - SUNY Cortland, Department Of Biological Sciences, P.O. Box 2000, Cortland, NY, 13045, United States
2 - University of California, Riverside, Botany and Plant Sciences, Riverside, CA, 92521, USA
3 - University of California, Riverside, Botany and Plant Sciences, 900 University Ave., Riverside, CA, 92521, USA
4 - University Of California, Riverside, Botany And Plant Sciences, 900 University Avenue, Riverside, CA, 92521, United States

Keywords:
allopolyploidy
anthocyanin
evolution
flower color
homeolog expression bias
Nicotiana.

Presentation Type: Oral Paper
Session: HYHY1, Hybrids and Hybridization
Location: Tucson H/Starr Pass
Date: Wednesday, July 31st, 2019
Time: 11:00 AM
Number: HYHY1010
Abstract ID:577
Candidate for Awards:Margaret Menzel Award