Poster: Cytoskeleton structure & dynamics
Abs #
681: Diverse Actin Depolymerizing Factors in Arabidopsis
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Presenter: |
Ruzicka, Daniel R, druzicka@uga.edu |
Authors | Ruzicka, Daniel R (A) McKinney, Elizabeth C (A) Deal, Roger B (A) Kandasamy, Muthugapatti K (A) Burgos, Brunilis (A) Meagher, Richard B (A) | | Affiliations: |
(A): University of Georgia, Department of Genetics
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Higher plants encode at least three ancient clades of actin depolymerizing factors (ADFs), an actin binding protein that severs actin filaments. The Arabidopsis genome encodes 11 ADF genes in these three ancient clades. We are attempting to knock down the expression of each of the three clades separately to determine their functional contributions. RNA interference (RNAi) is being used to target the multiple gene family members in the ADF4 (five genes), the ADF8 (four genes), and the ADF9 (two genes) clades. A novel inverted repeat-PCR (IR-PCR) method was used to make each RNAi construct. Multiple sequences from the 3ŽUTR of each gene in a clade were arrayed along both sides of the inverted repeat structure separated by a GUS linker. This stem-loop RNA was expressed from a constitutive actin A2pt expression vector. Transgenic Arabidopsis plants will be examined for ADF deficient phenotypes.
We have proposed that subclasses of actin binding proteins (e.g., the different clades of ADFs) co-evolved with the ancient vegetative and reproductive actins following gene duplications dating to more than 300 million years ago. Ectopic expression of reproductive actin ACT1 in vegetative tissues resulted in strong and pleiotropic phenotypes including alterations in organ shape and number, extreme dwarfing, and bizarre cytoskeletal structures, whereas over-expression of vegetative ACT2 produced no phenotypes. Preliminary data suggest that ectopically expressed pollen ADF8 can suppress this ectopic ACT1 phenotype. We propose that this suppression is due to more efficient recognition and cleavage of ACT1 filaments by ADF8 in vegetative tissues than by endogenous vegetative ADFs.
