Abstract Detail

Functional Genetics/Genomics

Sain, Melody [1], Baum, David [2].

Identifying Loci Linked to Homeotic Sexual Dimorphism in Dioecious Meadow-rues (Thalictrum L., Ranunculaceae).

Although only 5-6% of angiosperms species show dioecy, it is phylogenetically widespread, occurring in 43% of angiosperm families, pointing to multiple origins of this breeding system. The genus Thalictrum L. (meadow-rue, Ranunculaceae) includes two distinct dioecious clades one of which has been shown to have male heterogametic sex determination. Thalictrum flowers have free carpels or free stamens whose youngest primordia are very similar, suggesting the possibility that sex determination is at least partly homeotic in nature, potentially involving differential expression or activity of MADS-box floral organ identity genes. Since the genetic basis of sex determination is known for only a few plants to date, with none known to directly utilize homeotic genes, we aim to elucidate the genomic architecture of Thalictrum sex determination in representatives of both dioecious clades. We hope to learn whether the transition from hermaphroditism to dioecy occurred via the same molecular pathways in each independent origin and whether either involves changes in B-class MADS-box genes or known regulators of these organ identity genes. Using Illumina whole genome sequencing of bulked males and females of Thalictrum dioicum L. I have confirmed male heterogamety and have found that ~0.18% of the genome is male-specific. Future work will entail a more complete genome assembly and annotation of sex-linked contigs for T. dioicum. Then, by conducting similar analysis of a representative of the other dioecious clade, T. dasycarpum, we will be able to examine the degree of parallelism involved and shed light on the repeatability of sexual system evolution in flowering plants.

1 - University of Wisconsin-Madison, 430 Lincoln Drive, 220 Birge Hall, Madison, Wisconsin, 53706, United States
2 - University Of Wisconsin, Department Of Botany, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, United States

Keywords:
Dioecy
sex determination
Thalictrum 
homeotic
Ranunculaceae
evolution
genomics.

Presentation Type: Oral Paper
Session: FG1, Functional Genetics and Genomics
Location: San Luis 1/Starr Pass
Date: Monday, July 29th, 2019
Time: 3:00 PM
Number: FG1005
Abstract ID:909
Candidate for Awards:Margaret Menzel Award