Int. J. Dev. Biol. 45: S51 - S52 (2001)
© UPV/EHU Press

ULTRACURVATA1, a SHAGGY-like Arabidopsis gene required for cell elongation

JM Perez-Perez, MR Ponce, JL Micol

Univ Miguel Hernandez, Div Genet, Alicante 03202, Spain; Univ Miguel Hernandez, Inst Bioingn, Alicante 03202, Spain

ABSTRACT To better understand the genetic mechanisms underlying plant leaf development, we have performed a large-scale screening for Arabidopsis thaliana mutants to identify those displaying abnormally shaped or sized leaves. One of the stronger mutant phenotypes found was that of the ultracurvata1 (ucu1) mutants, whose vegetative and cauline leaves are spirally rolled downwards and show a reduced expansion along the longitudinal axis, in contrast to wild type leaves, which are flattened organs. We have identified one recessive and two semidominant ucu1 alleles, the most extreme of which cause severe dwarfism and a constitutive photomorphogenic response. Following a map-based strategy, we have cloned the UCU1 gene, which was found to encode an intracellular kinase closely related to SHAGGY, one of the components of the Wingless/Wnt animal signalling pathway. The responses of ucu1 mutants to exogenous plant hormones and the genetic analyses of double mutants involving ucu1 alleles indicate that UCU1 is a key component in several signalling pathways controlling cell expansion and overall plant growth, including those of auxins and brassinosteroids.