Poster: Emerging technologies

Abs # 915: Abscission regulation: a cell-specific functional genomic approach

Presenter:	Cai, Suqin , sqcai@iastate.edu
Authors	Cai, Suqin  (A)   Rosin, Faye M. (A)   Lashbrook, Coralie C. (A)
Affiliations:	(A): Iowa State University Horticulture Department

The shedding of organs in response to developmental or environmental cues is termed abscission. Many current understandings of abscission control are based on biochemical and physiological studies of hormones that coordinately regulate detachment. The widely cited ethylene: auxin balance theory of abscission control maintains that a flow of inhibitory auxin from tissues of an organ destined to abscise prevents cell separation within an abscission zone (AZ) until auxin levels drop and ethylene action is de-repressed. But key features of this model first developed in leaf systems have not yet been tested at the molecular genetic level in any organ. Arabidopsis is an ideal system in which to exploit functional genomic strategies to elucidate molecular mechanisms that underlie the hormonal control of abscission. But petal shed in this species takes place in a restricted tier of very small AZ cells whose manual dissection from surrounding tissues presents a large technological hurdle. As the first step towards developing Arabidopsis as a functional genomic system for abscission studies, we optimized laser capture microdissection (LCM) methods capable of isolating highly enriched populations of petal abscission zone cells from paraffin-embedded flowers. Using both the Arcturus PixCell LCM system and Zeiss’s PALM laser pressure catapulting method we have purified abscission zone mRNA of high purity and integrity for use as hybridization targets in microarray studies. Development of cell-specific functional genomic tools will facilitate future identification of novel genes and gene populations whose expression may coordinately regulate ethylene and auxin control of organ abscission.