The Big Ten National Academy of Sciences seminar series continues with the University of Wisconsin's Richard Amasino at 4 p.m., Nov. 9 in E103 Beadle Center. The seminar and a 3:30 p.m. reception are free and open to the public.
Amasino is a professor of biochemistry. His lecture topic is "Memories of Winter: Vernalization is an Environmentally Induced Epigenetic Switch."
Certain plants, such as biennials or winter annuals, require relatively long periods of cold exposure during winter to initiate flowering the following spring. Cold exposure renders the meristem of such cold-requiring species competent to flower. This acquisition of competence to flower is known as vernalization. Before competence is achieved, plants must measure exposure to a sufficient number of days of cold to represent a complete winter; this ensures flowering only occurs when spring has arrived, rather than during a temporary warming in the middle of winter.
Amasino's research has revealed that, in Arabidopsis, vernalization-mediated meristem competence is a function of the expression level of the MADS-box gene flowering locus C. The FLC gene is a repressor of flowering. Exposure to prolonged cold causes epigenetic silencing of FLC, thus rendering the shoot apical meristem competent to flower. During cold exposure, chromatin-remodeling complexes catalyze covalent modification of histones of FLC chromatin resulting in silencing of expression. Studies in other groups of plants reveal that the vernalization requirement is based on components different than those in Arabidopsis, but to date all vernalization pathways are “overlaid” on a conserved flowering pathway that is often involved in photoperiod sensing.
More details at: http://go.unl.edu/txw