Abstract Detail

Evolutionary Developmental Biology (Evo-Devo)

Kim, Joon [1], Zhang, Jingbo [2], Zhang, Wenheng [3].

The roles of CYC2-like genes in the floral development in Solanum lycopersicum and Nicotiana obtusifolia (Solanaceae).

The CYC2-like genes are thought to play a critical role in the convergent evolution of floral zygomorphy in core eudicots, yet their roles in the development of actinomorphic flowers are still unknown. We have recently identified a gene duplication of CYC2 clade that gave rise to two CYC2 paralogs, CYC2A and CYC2B, which predate the origin of Solanaceae, a family producing predominantly actinomorphic flowers. Both CYC2 paralogs appear to be involved in floral development in Solanaceae. In S. lycopersicum, CYC2A is broadly expressed in the floral meristem and early initiating floral organs and later explicitly in the pollen sacs and the ovules. In N. obtusifolia, the expression of CYC2A was detected in two dorsal stamens and carpels. The expression of CYC2B was in the sepals of both species. Here, we sought to investigate the function of these CYC2 paralogs in S. lycopersicum and N. obtusifolia using virus-induced gene silencing (VIGS) to silence both CYC2A and CYC2B simultaneously. The VIGS CYC2A::CYC2B plants of S. lycopersicum frequently bore flowers with six petals, six sepals, and six stamens, while the VIGS CYC2A::CYC2B of N. obtusifolia frequently produced flowers with four petals, four sepals, and four stamens. No obvious changes were observed in the carpels for VIGS CYC2A::CYC2B plants of both species. Since we found CYC2A to be expressed in the stamens of both species, especially in the microsporocyte within the anthers in S. lycopersicum, we also investigated whether the development of pollen was influenced in VIGS CYC2A::CYC2B plants by observing the pollen and pollen tube germination in both species. We found pollens from the VIGS CYC2A::CYC2B plants to be darker purple than in the wild type after applying Alexander’s stain, suggesting different cytoplasm contents between the VIGS CYC2A::CYC2B plants and the wild type. Pollen germination tests showed pollen tubes from the VIGS CYC2A::CYC2B plants to be significantly reduced in length compared to the wild type. Our findings, therefore, suggest that CYC2-like genes likely play a role in the early meristem patterning of the meristem in the calyx, corolla, androecium and in pollen development in Solanaceae.

1 - Virginia Commonwealth University, Integrative Life Sciences , 1000 West Cary Street, Richmond, VA, 23284, USA
2 - Department Of Biology, Virginia Commonwealth University, 1000 West Cary Street, Life Science Building 336, Richmond, VA, 23284, United States
3 - Virginia Commonwealth University, Department Of Biology, 1000 W Cary Street, Richmond, VA, 23284, United States

Keywords:
Solanaceae
Solanum lycopersicum
TCP genes
Nicotiana obtusifolia
Tobacco Rattle Virus
Virus-Induced gene silencing
VIGS
Floral development
Reverse genetics
actinomorphy
CYC2-like genes
CYCLOIDEA.

Presentation Type: Oral Paper
Session: 20, Evolutionary Developmental Biology (Evo-Devo) I
Location: 113/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 9:00 AM
Number: 20005
Abstract ID:817
Candidate for Awards:Katherine Esau Award