Abstract Detail

Hybrids and Hybridization

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

Homeolog expression bias increases with allopolyploid age, but does not correlate with floral color differences in Nicotiana tabacum allopolyploids.

Allopolyploidy, the phenomenon which includes both whole genome duplication and interspecific hybridization, has played a significant role in the evolution of angiosperms.  Many studies have documented the genomic, chromosomal, expression, and phenotypic changes that result following allopolyploidy, but few studies have linked these genetic and phenotypic changes.  Here, we use several accessions of natural Nicotiana tabacum, which arose ~0.6 million years ago, its diploid progenitors, and first-generation synthetic lines produced from crosses between the same progenitor species to determine whether changes in homeolog expression bias among allopolyploid accessions correlate with observed changes in floral color.  Nicotiana tabacum accessions vary in floral color between light pink and dark pink whereas the maternal progenitor, N. sylvestris, has white flowers, and the paternal progenitor, N. tomentosiformis, has dark pink flowers.  Changes in the composition of cyaninidin and flavonol pigments account for these differences in floral color.  Cyanindin and flavonols are produced by the flavonoid biosynthetic pathway, which is a branched pathway that has been well characterized, allowing for investigation into the genetic basis of floral color and the role of homeolog expression bias in the observed differences in floral color among N. tabacum accessions.  Using long read sequences from the diploid progenitors using Oxford Nanopore technology in addition to Illumina transcriptome data increased the quality of de novo assemblies, resulting in ~11,000 fewer contigs and an increase in the N50 by ~800bp compared to the Illumina only assembly, and allowed for us to distinguish between homeologous sequences.  Overall, the magnitude of homeolog expression bias increased with allopolyploid age, but both natural and synthetic N. tabacum accessions displayed similar deviation from progenitor expression ratios.  Additionally, changes in floral color do not seem to correlate with changes in homeolog expression bias.  However, low expression of DIHYDROFLAVONOL 4-REDUCTASE (DFR), the first enzyme in the pathway toward the production of anthocyanins, early on in floral development correlates with the light pink floral phenotype.  In addition, increased expression of the N. tomentosiformis copy of DFR in allopolyploids with dark pink flowers is observed in all comparisons between light and dark pink N. tabacum accessions.

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, 900 University Ave., Riverside, CA, 92521, USA
3 - University Of California, Riverside, Botany And Plant Sciences, 900 University Avenue, Riverside, CA, 92521, United States
4 - Cornell University, Plant Biology and the L.H. Bailey Hortorium, School of Integrative Plant Science, 506 Mann Library Building, Ithaca, NY, 14850, USA

Flower color
homeolog expression bias

Presentation Type: Oral Paper
Session: HYHY1, Hybrids and Hybridization
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 1:30 PM
Number: HYHY1005
Abstract ID:412
Candidate for Awards:None

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