Mutation in the Arabidopsis PASTICCINO1Gene, Which Encodes a New FK506-Binding Protein-Like Protein, Has a Dramatic Effect on Plant Development

ABSTRACT

The pasticcino (pas) mutants ofArabidopsis thaliana are a new class of plant developmental mutants; members of this class show ectopic cell proliferation in cotyledons, extra layers of cells in the hypocotyl, and an abnormal apical meristem. This phenotype is correlated with both cell division and cell elongation defects. There are three complementation groups ofpas mutants (pas1, pas2, and pas3, with, respectively 2, 1, and 4 alleles). Here we describe in more detail the pas1-1 allele, which was obtained by insertional mutagenesis. The PAS1 gene has been cloned and characterized; it encodes an immunophilin-like protein similar to the p59 FK506-binding protein (FKBP52). PAS1 is characterized by an FKBP-like domain and three tetratricopeptide repeat units. Although the presence of immunophilins in plants has already been demonstrated, the pas1-1 mutant represents the first inactivation of an FKBP-like gene in plants. PAS1expression is altered in pas1 mutants and in the pas2 and pas3 mutants. The expression of the PAS1 gene is increased in the presence of cytokinins, a class of phytohormones originally discovered because of their ability to stimulate cell division. These results are of particular relevance as they show for the first time that an FKBP-like protein plays an important role in the control of plant development.

ACKNOWLEDGMENTS

P.V. was supported by an INRA postdoctoral fellowship from DSPV.

We are grateful to G. Pelletier and his group for providing the T-DNA lines, to B. Courtial for RFLP analysis, and to T. Desprez for technical assistance with software analysis. The A. thalianagenomic and cDNA libraries were kindly provided by J. Mulligan and C. Robaglia, respectively. We also thank E. E. Baulieu and his group for helpful discussions and for the gift of the FK506 and rapamycin molecules and Heather Mckhann and Isabelle Barlier for critical reading of the manuscript.