Molecular Plant Advance Access originally published online on March 31, 2009
Molecular Plant 2009 2(3):526-534; doi:10.1093/mp/ssp016
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Prefoldins 3 and 5 Play an Essential Role in Arabidopsis Tolerance to Salt Stress
Departamento de Biología de Plantas, Centro de Investigaciones Biológicas–CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain
1 To whom correspondence should be addressed. E-mail salinas{at}cib.csic.es, fax 34 91 536 0432, tel. 34 91 837 3112 Ext. 4303.
During the last years, our understanding of the mechanisms that control plant response to salt stress has been steadily progressing. Pharmacological studies have allowed the suggestion that the cytoskeleton may be involved in regulating such a response. Nevertheless, genetic evidence establishing that the cytoskeleton has a role in plant tolerance to salt stress has not been reported yet. Here, we have characterized Arabidopsis T-DNA mutants for genes encoding proteins orthologous to prefoldin (PFD) subunits 3 and 5 from yeast and mammals. In these organisms, PFD subunits, also known as Genes Involved in Microtubule biogenesis (GIM), form a heterohexameric PFD complex implicated in tubulin and actin folding. We show that, indeed, PFD3 and PFD5 can substitute for the loss of their yeast orthologs, as they are able to complement yeast gim2
and gim5 mutants, respectively. Our results indicate that pfd3 and pfd5 mutants have reduced levels of 
- and β-tubulin compared to the wild-type plants when growing under both control and salt-stress conditions. In addition, pfd3 and pfd5 mutants display alterations in their developmental patterns and microtubule organization, and, more importantly, are hypersensitive to high concentrations of NaCl but not of LiCl or mannitol. These results demonstrate that the cytoskeleton plays an essential role in plant tolerance to salt stress.
Key Words: Prefoldins • cytoskeleton • tubulin • actin • microtubule • salt tolerance • Arabidopsis