Poster: Cytoskeleton: Structure & Function

Abs # 1122: AtPAKRP2, a phragmoplast-associated kinesin motor protein, plays an essential role in cytokinesis

Presenter:	Lee, Yuh-Ru J, yjlee@ucdavis.edu
Authors	Lee, Yuh-Ru J (A)   Liu, Bo  (A)
Affiliations:	(A): University of California, Davis

During cytokinesis in plant cells, cell plate formation requires coordinated microtubule reorganization and vesicle transport in the phragmoplast. Microtubule-based kinesin motor proteins are important players in both processes. To understand mechanisms underlying plant cytokinesis, we have identified a kinesin motor protein AtPAKRP2, for Arabidopsis thaliana phragmoplast-associated kinesin-related protein 2. AtPAKRP2 associated with microtubules in an ATP-dependent manner and was highly expressed in dividing cells. Immunofluorescence microscopy had shown that AtPAKRP2 first appeared in a punctate pattern among interzonal microtubules during late anaphase. Along progression of cytokinesis, AtPAKRP2 became more concentrated near the division site, and additional signals were detected elsewhere in the phragmoplast. To gain insights into the function of AtPKARP2, we used a glucocorticoid-inducible promoter to ectopically express the AtPAKRP2 antisense gene in A. thaliana. While the antisense transgenic seedlings grew normally under non-induced conditions, the expression of the AtPAKRP2 antisense gene caused growth inhibition of transgenic seedlings. Both the hypocotyl and the root of the seedlings expressing the antisense AtPKARP2 gene had very limited growth and bumpy surface. The cotyledon of the antisense seedlings did not expand completely and the shoot stopped growth before the first pair of leaves emerged. Incomplete cell plate was observed in antisense seedlings showing stunned growth. Our results indicate that AtPAKRP2 plays an essential role in cytokinesis. This work was supported by a USDA CSREES/NRICGP grant.