Poster: Vegetative Development

Abs # 428: Characterization of the vascular-network defective mutant, van3, of arabidopsis

Presenter:	Koizumi, Koji , koizumik@nodai.ac.jp
Authors	Koizumi, Koji  (A)   Naramoto, Satoshi  (B)   Sawa, Shinichiro  (B)   Tanaka, Shigeo  (A)   Sugiyama, Munetaka  (C)   Fukuda, Hiroo  (B)
Affiliations:	(A): Department of Bioscience, Faculty of Applied Bioscience,Tokyo University of Agriculture (B): Department of Biological Sciences, Graduate School of Science, The University of Tokyo (C): Botanical Garden, Graduate School of Science, The University of Tokyo

To dissect vascular pattern formation genetically, we have isolated and analyzed van mutants of arabidopsis that are characterized by fragmented minor veins. Here we report putative auxin distribution in relation with vein development of the van3 mutant and genetic interaction between VAN3 and auxin-related genes. Putative auxin distribution was analyzed using a fusion gene of an auxin-inducible promoter and a reporter, DR5::GUS. In the formation of tertiary veins of wild-type plants, GUS staining was observed as a dotted pattern in provascular cells and the stained cells were interspersed between secondary veins, suggesting that differentiation of provascular cells may start with auxin accumulation. In the van3 mutant, the spatial pattern of stained cells was not changed greatly but their number was reduced substantially. To understand the relation between polar auxin transport and the VAN3 product, we generated double mutants of van3 with pin1, emb30/gnom, and mp. The van3 pin1 and van3 emb30/gnom double mutants displayed the sum of two mutant phenotypes, suggesting that VAN3 and polar auxin transport system do not act in the same pathway toward vascular pattern formation. These results, taken together with results of other double mutants, will be discussed in view of VAN3 function in vascular pattern formation.