Abstract Detail

Comparative Genomics/Transcriptomics

Shan, Shengchen [1], Boatwright, J. Lucas [2], Liu, Xiaoxian [3], Chanderbali, Andre [4], Fu, Chaonan [5], Soltis, Pamela [6], Soltis, Douglas [6].

Transcriptome dynamics of the inflorescence in reciprocally formed allopolyploid Tragopogon miscellus (Asteraceae).

Polyploidy is an important evolutionary mechanism and is prevalent among land plants. Most polyploid species examined have multiple origins, which provide genetic diversity and may enhance the success of polyploids. In some polyploids, recurrent origins can result from reciprocal crosses between the same diploid progenitors. Although great progress has been made in understanding the genetic consequences of polyploidy, the genetic implications of reciprocal polyploidization remain poorly understood, especially in natural polyploids. Tragopogon (Asteraceae) has become an evolutionary model system for studies of recent and recurrent polyploidy. Allotetraploid T. miscellus has formed reciprocally in nature with resultant distinctive floral and inflorescence morphologies (i.e., short- vs. long-liguled forms). In this study, we performed comparative inflorescence transcriptome analyses of reciprocally formed T. miscellus and its diploid parents, T. dubius and T. pratensis. In both forms of T. miscellus, homeolog expression of ~70% of the loci showed vertical transmission of the parental expression patterns (i.e., parental legacy), and ~20% of the loci showed biased homeolog expression, which was unbalanced toward T. pratensis. However, 17.9% of orthologous pairs showed different homeolog expression patterns between the two forms of T. miscellus. No clear effect of cytonuclear interaction on biased expression of the maternal homeolog was found. In terms of the total expression level of the homeologs studied, 22.6% and 16.2% of the loci displayed nonadditive expression in short- and long-liguled T. miscellus, respectively. Unbalanced expression level dominance toward T. pratensis was observed in both forms of T. miscellus. Significantly, genes annotated as being involved in pectin catabolic processes were highly expressed in long-liguled T. miscellus relative to the short-liguled form, and the majority of these differentially expressed genes were transgressively down-regulated in short-liguled T. miscellus. Given the known role of these genes in cell expansion, they may play a role in the differing floral and inflorescence morphologies of the two forms. In summary, the overall inflorescence transcriptome profiles are highly similar between reciprocal origins of T. miscellus. However, the dynamic nature of homeolog-specific expression and nonadditive expression patterns observed in reciprocally formed T. miscellus emphasize the importance of recurrent origins in promoting the genetic diversity of polyploids.

1 - 322 University Village South, Apartment 6, Gainesville, FL, 32603, United States
2 - Advanced Plant Technology Program, Clemson University, Clemson, SC
3 - Department of Biology, University of Florida, Gainesville, FL, 32611, USA
4 - 357 Dickinson Hall Museum Road & Newell Drive, P.o. Box 117800, Gainesville, FL, 32611, United States
5 - Kunming Institute of Botany, Kunming, China
6 - University Of Florida, Florida Museum Of Natural History, Dickinson Hall, Gainesville, FL, 32611, United States
7 - University Of Florida, Florida Museum Of Natural History, Dickinson Hall, Gainesville, FL, 32611, United States

Keywords:
homeolog
inflorescence
nonadditive expression
polyploidy
reciprocal formation
Tragopogon
transcriptome.

Presentation Type: Oral Paper
Session: CG2, Functional & Comparative Genetics/Genomics II
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 4:30 PM
Number: CG2007
Abstract ID:413
Candidate for Awards:Margaret Menzel Award