Poster: Reproductive Development

Abs # 484: Mechanisms regulating floral scent emission after pollination.

Presenter:	Dudareva, Natalia , dudareva@hort.purdue.edu
Authors	Dudareva, Natalia  (A)   Negre, Florence  (A)   Kish, Christine  (A)   Boatright, Jennifer  (A)   Underwood, Beverly  (B)   Shibuya, Kenichi  (B)   Clark, David G (B)   Gorenstein, Nina  (A)   Wagner, Conrad  (C)
Affiliations:	(A): Purdue University (B): University of Florida (C): Vanderbilt University

Plants attract pollinators by producing and emitting scent compounds which play a prominent role in the location and selection of flowers by insects. In many flowering plants floral scent emission decreases after pollination thereby directing insects to unpollinated flowers. Here we show that emission of methyl benzoate, one of the major scent compounds in both snapdragon and petunia decreases in pollinated flowers only after fertilization. However, petunia and snapdragon flowers use different mechanisms which depend on the ethylene sensitivity of their scent biosynthetic genes to down-regulate scent production. In petunia, expression of the gene responsible for methyl benzoate synthesis is suppressed by ethylene. In snapdragon the decrease in floral scent emission is not ethylene dependent. Rather, the accumulation of S-adenosylhomocystein after fertilization accounts for the inhibition of S-adenosyl-L-methionine: benzoic acid carboxyl methyltransferase (BAMT) activity and loss of methyl benzoate emission. Different mechanisms to switch off scent emission after fertilization may have evolved to maximize reproductive success depending on whether flowers are solitary or grouped in an inflorescence where the volatile nature of ethylene could affect scent emission in nonpollinated flowers.