Developmental and Structural Section
Wang, Yunjing , Ballard, H. E. , McNally, R. Ryan , Wyatt, Sarah .
Identification and characterization of the floral genes in a cleistogamous species Viola pubescens (Violaceae).
Many plants, including most species in the genus Viola, can produce both open (chasmogamous) and closed (cleistogamous) flowers. Chasmogamous and cleistogamous flowers produce seeds by outcrossing and selfing respectively, and the mixed breeding system is considered a successful reproductive strategy. But the underlying molecular basis of the floral dimorphism is not known. Gibberellic acid (GA) functions in triggering flowering and has been suggested to play some roles in the floral dimorphism. The LEAFY (LFY) gene of Arabidopsis and its orthologs in other plants are responsible for the initiation of floral meristems and the regulation of the downstream flower development. Afterward, the ABCE classes of floral organ identity genes collaborate to give rise to a flower. The GA20 and GA3 oxidases (two key enzymes in GA biosynthesis), LFY and most of the ABCE floral gene orthologs of a widespread North American violet, V. pubescens, were identified by polymerase chain reaction (PCR). Semi-quantitative reverse transcriptase-PCR indicated that all the genes were expressed in both types of flowers, but the expression levels showed significant differences. Both VGA20 and VGA3 oxidase genes were expressed more in chasmogamous flowers than in cleistogamous flowers. At least four VLFY gene transcripts were detected, and different transcripts displayed different expression patterns between the two types of flowers. The A class genes were expressed equally in both types of flowers. Expression of B class genes was increased in chasmogamous flowers as compared to cleistogamous flowers, while the C class genes’ expression was much more reduced in chasmogamous flowers than in cleistogamous flowers. Overall, the differential expression of the floral genes explained the morphological differences between the two flower types. Our study provided the first step to understanding the molecular control of the floral dimorphism. We are currently investigating the regulation of the floral genes of Viola pubescens.
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1 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
2 - Ohio University, Environmental and Plant Biology, 317 Porter Hall, Ohio University, Athens, Ohio, 45701, USA
ABCE floral genes.
Presentation Type: Oral Paper:Papers for Sections
Location: Boulevard C/Hilton
Date: Tuesday, July 10th, 2007
Time: 9:30 AM