Title

Understanding the cytokinin N-glucosylation pathway using Arabidopsis Mutants

Date of Completion

January 2009

Keywords

Agriculture, Horticulture|Biology, Plant Physiology

Degree

Ph.D.

Abstract

N-glucosylation is considered to be a cytokinin inactivation mechanism in plants. We have isolated a mutant in Arabidopsis thaliana, roscovitine-resistant (ror-1) using T-DNA tagged lines that may encode a gene that plays a role in cytokinin N-glucosylation. The amount of N-glucosides was 20% more in ror-1 mutant compared to WT. The cytokinin oxidase activity showed an 11% increase in ror-1 compared to WT in basal media. Additionally, ror-1 plants showed resistance to exogenously supplied aromatic cytokinins (benzyladenine). Our data on relative expression of ROR-1 gene exhibited significant upregulation of ROR-1 gene in ror-1 plants incubated with 5 μM BA for 24 h. The in silico analysis showed that ROR-1 gene encoded a protein consisting of GRAM (Glycosyltransferases Rab-like GTPase activators and Myotubularins) and C2 domains. Here, we report that the ROR-1 gene plays a role in metabolizing active cytokinin pool in plants by specifically affecting aromatic cytokinin metabolism. ^