Poster: Integrated Plant Biology

Abs # 83: eRF1 over-expression causes 'broomhead' inflorescence structures in Arabidopsis

Presenter:	Petsch, Katie , k.petsch@botany.uq.edu.au
Authors	Petsch, Katie  (A)   Botella, Jimmy  (A)
Affiliations:	(A): University of Queensland, Botany Department

As part of a broader project, we have produced several Arabidopsis transgenic lines displaying a distinctive 'broomhead' phenotype by over-expression of the endogenous eukaryotic release factor 1 gene (AteRF1). Plants containing this construct prematurely terminate the growth of their inflorescence meristem, while the flowers at the apex continue to grow without the development of the proper inter-nodal distance forming a 'broomhead'-like cluster of malformed siliques. During the vegetative stage of development, transgenics resemble wild type plants, only showing the phenotype once they have switched to the reproductive stage. In addition, the severity of the phenotype is highly variable, both within a line and between lines. The percentage of transgenics showing the phenotype is low (0-50%) and also variable between lines. Northern analysis on transgenics confirmed over-expression of AteRF1 in all tissues examined, except those within the clustered broomhead structures. In these tissues partial and specific degradation of the transcript was observed, however, transcript levels still remain slightly higher than that of the wild type. Light microscopy of broomhead regions showed a reduction in cell length by half and lignification of parenchyma cells in the intra- and inter-fascicular regions. No other cellular areas exhibited abnormalities, suggesting the phenotype may be an effect of localised gene silencing.