Abstract Detail

Functional Genetics/Genomics

Sain, Melody [1], Baum, David [2].

Identifying Sex-Segregating Loci to Begin Elucidating the Parallel Origin of Sex Determination and Homeotic Sexual Dimorphism in Thalictrum L.

In animals, separate sexes are the norm, but plant sporophytes are more commonly bisexual than unisexual. Although only 5-6% of angiosperms species show dioecy, it is phylogenetically widespread, occurring in 43% of angiosperm families, pointing to multiple origins of sporophyte unisexuality. Two of these origins are in the genus Thalictrum L. (meadow-rue, Ranunculaceae), which includes two distinct dioecious clades, one of which has been shown to have a male heterogametic sex determination system. Unlike most dioecious taxa, unisexual 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, thus suggesting a potential role for differential expression or activity of MADS-box floral organ identity genes. We aim to elucidate the genomic architecture of Thalictrum sex determination in the two dioecious clades in order to determine whether the transition from hermaphroditism to dioecy occurred via the same molecular pathways and whether either case involves changes in B-class MADS-box genes or their upstream known regulators. Using whole genome sequencing of bulked males and females of T. dioicum L. we have confirmed male heterogamety and have estimated that ~0.18% of the genome is male-specific. We are assembling a complete draft genome for male T. dioicum and aim to annotate sex-linked contigs to identify candidate genes whose expression can be studied. In the future we plan to conduct similar analyses of a representative of the other dioecious clade, T. dasycarpum. This work will shed light on the potential role of homeosis in sex determination and on the repeatability of sexual system evolution in flowering plants.

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

Keywords:
Thalictrum
sex determination
Dioecy  
Ranunculaceae
sexual dimorphism
genomics
whole genome sequencing
Illumina.

Presentation Type: Poster
Session: P2, Functional Genetics and Genomics Posters
Location: Virtual/Virtual
Date: Tuesday, July 20th, 2021
Time: 5:00 PM(EDT)
Number: P2CG006
Abstract ID:1049
Candidate for Awards:None