Arabidopsis RAB geranylgeranyl transferase beta-subunit mutant is constitutively photomorphogenic, and has shoot growth and gravitropic defects

0350388 - ÚEB 2011 RIV GB eng J - Journal Article
Hála, Michal - Soukupová, Hana - Synek, Lukáš - Žárský, Viktor
Arabidopsis RAB geranylgeranyl transferase beta-subunit mutant is constitutively photomorphogenic, and has shoot growth and gravitropic defects.
Plant Journal. Roč. 62, č. 4 (2010), s. 615-627. ISSN 0960-7412. E-ISSN 1365-313X
R&D Projects: GA ČR GP204/06/P467; GA AV ČR KJB600380802
Institutional research plan: CEZ:AV0Z50380511
Keywords : RAB GTPases * cell expansion * photomorphogenesis
Subject RIV: EA - Cell Biology
Impact factor: 6.948, year: 2010

RAB GTPases are key regulators of intracellular vesicle transport. They are modified by geranylgeranylation catalyzed by the RAB geranylgeranyl transferase (RAB-GGT). Here, we show that RAB-GGT activity is significantly reduced in two homozygous mutants of the major Arabidopsis beta-subunit of RAB-GGT (AtRGTB1), resulting in unprenylated RAB GTPases accumulation in the cytoplasm. Both endocytosis and exocytosis are downregulated in rgtb1 homozygotes defective in shoot growth and morphogenesis. Root gravitropism is normal in rgtb1 roots, but is significantly compromised in shoots. Mutants are defective in etiolation and show constitutive photomorphogenic phenotypes that cannot be rescued by brassinosteroid treatment, similarly to the secretory det3 mutant. Transcriptomic analysis revealed an upregulation of specific RAB GTPases in etiolated wild-type plants. These data suggest that the downregulation of the secretory pathway is interpreted as a photomorphogenic signal in Arabidopsis.
Permanent Link: http://hdl.handle.net/11104/0190404