Abstract Detail

Development and Structure

Tong, Jingjing [1], Knox, Eric [2], Morden, Clifford [3], Cellinese, Nico [4], Mossolem, Fatima [1], Zubair, Aarij [1], Howarth, Dianella G. [1].

Duplication and Expression Patterns of CYCLOIDEA-like genes in Campanulaceae.

Campanulaceae, with roughly 2,400 species, comprises five subfamilies, defined in part, by differences in their floral orientation and symmetry, with broad transitions between radial and bilateral floral symmetry. Evidence from numerous comparative studies across angiosperms indicates that CYCLOIDEA-like transcription factors play an important role in dorsoventral asymmetry in flowering plants. In core eudicots, two duplications have led to three clades of CYC-like genes: CYC1, CYC2, and CYC3, with the CYC2 clade containing the dorsally expressed CYC gene. We identify here all three CamCYC paralogs from across Campanulaceae. Similar to other groups, we show that CamCYC2 duplicated around the divergence of the bilaterally symmetrical Lobelioideae. However, in bilaterally symmetrical Cyphioideae, we detected two duplicate CamCYC3 genes but no CamCYC2 genes in this clade, suggesting that CamCYC3 genes might be involved in the development of bilaterally symmetrical flowers in this clade instead of CamCYC2. This is the first known case of a loss of CYC2-like genes in a bilaterally symmetrical lineage. Within the radially symmetrical Campanuloideae, only CamCYC1 is duplicated. We utilized qRT-PCR to examine the correlation between CYC-like gene expression and shifts in flower morphology in four species of bilaterally symmetrical Lobelioideae. As expected, CamCYC2 genes showed dorsoventrally restricted expression in bilateral symmetrical flowers. However, because Lobelioideae have resupinate flowers (turned 180°), both CamCYC2A and CamCYC2B are highly expressed in the visually ventral petals, which correspond to the genetically dorsal side of the flower, suggesting conservation of dorsal identity in the upside-down flower. Additionally, while all four species examined exhibited differential expression levels in CamCYC2A and CamCYC2B genes, in species with dorsal petals longer than ventral, CamCYC2A exhibited higher expression, while species with higher CamCYC2B expression have dorsal and ventral petals of approximately equal size.

1 - St. John's University, Biological Sciences , 8000 Utopia Pkwy, Jamaica, New York, 11439, United States
2 - Indiana University , Biology , 107 S Indiana Ave, Bloomington, 47405, United States
3 - University of Hawai'i , Botany, 3190 Maile Way , Honolulu, HI , 96822, United States
4 - University of Florida, FLORIDA MUSEUM OF NAT. HISTORY, 1659 Museum Rd, 354 Dickinson Hall, Gainesville, FL, 32611, United States

Keywords:
Campanulaceae
Flower architecture
CYCLOIDEA
Gene duplication
gene expression.

Presentation Type: Oral Paper
Session: DS2, Development and Structure II
Location: /
Date: Wednesday, July 21st, 2021
Time: 10:30 AM(EDT)
Number: DS2003
Abstract ID:378
Candidate for Awards:Katherine Esau Award