Poster: Reproductive development

Abs # 369: The nectary transcriptome reveals novel features of this unusual floral organ

Presenter:	Thornburg, Robert , thorn@iastate.edu
Authors	Thornburg, Robert  (A)   Yin, De Lu  (A)   Taylor, Kyle  (A)   Carter, Clay  (A) (B)  Guirgis, Adel  (A) (C)
Affiliations:	(A): Iowa State University (B): University of California, Riverside (C): Menofiya University
Web Site:	http://www.bb.iastate.edu/~necgex/

We have sequenced 3300 nectary expressed ESTs from two stages of flowers from ornamental tobacco. These stages were: Stage 6 (pre-secretory, immature nectaries) and from 12 (mature nectaries at anthesis). Analysis of these sequences revealed several unique features of nectary gene expression and function. First, this analysis identified all of the Nectarin genes that are secreted into tobacco nectar. This analysis verified that a high percentage of transcripts express defense related genes, implying an important role for the nectary in floral defense. Genes involved in protein degradation are more highly expressed at floral maturity (Stage 12) than at Stage 6. About 14% of the genes identify metabolic functions and indicate the activity of a number of unique biochemical pathways operating in the floral nectary. Several alternatively spliced genes were identified. About 32% of the nectary genes correspond to unknown transcripts that are present in the GenBank. The identification that these previously unknown genes are expressed in the floral nectary should provide new clues to the function of these genes. Approximately 82 genes encoding transcription factors were identified that may play a role in nectary development and function. Studies involved with several of these transcription factor genes are ongoing. In addition, we are currently building a nectary unigene set for the preparation of microarrays to permit the complete analysis of nectary-expressed genes.