JXB Advance Access originally published online on May 14, 2009
Journal of Experimental Botany 2009 60(9):2653-2664; doi:10.1093/jxb/erp109
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
RESEARCH PAPER |
Altered expression of cytosolic/nuclear HSC70-1 molecular chaperone affects development and abiotic stress tolerance in Arabidopsis thaliana

1CEA, DSV, IBEB, F-13108 Saint-Paul-lez-Durance, France
2CNRS, UMR 6191 Biologie Vegetale et Microbiologie Environnementales, F-13108 Saint-Paul-lez-Durance, France
3Université de la Méditerranée Aix-Marseille II, F-13108 Saint-Paul-lez-Durance, France
To whom correspondence should be addressed. E-mail: laurent.noel{at}toulouse.inra.fr
Molecular chaperones of the heat shock cognate 70 kDa (HSC70) family are highly conserved in all living organisms and assist nascent protein folding in normal physiological conditions as well as in biotic and abiotic stress conditions. In the absence of specific inhibitors or viable knockout mutants, cytosolic/nuclear HSC70-1 overexpression (OE) and mutants in the HSC70 co-chaperone SGT1 (suppressor of G2/M allele of skp1) were used as genetic tools to identify HSC70/SGT1 functions in Arabidopsis development and abiotic stress responses. HSC70-1 OE caused a reduction in root and shoot meristem activities, thus explaining the dwarfism of those plants. In addition, HSC70-1 OE did not impair auxin-dependent phenotypes, suggesting that SGT1 functions previously identified in auxin signalling are HSC70 independent. While responses to abiotic stimuli such as UV-C exposure, phosphate starvation, or seedling de-etiolation were not perturbed by HSC70-1 OE, it specifically conferred
-ray hypersensitivity and tolerance to salt, cadmium (Cd), and arsenic (As). Cd and As perception was not perturbed, but plants overexpressing HSC70-1 accumulated less Cd, thus providing a possible molecular explanation for their tolerance phenotype. In summary, genetic evidence is provided for HSC70-1 involvement in a limited set of physiological processes, illustrating the essential and yet specific functions of this chaperone in development and abiotic stress responses in Arabidopsis.
Key words:
Arsenic, auxin, cadmium, co-chaperone, DnaK,
-ray, heat shock, HSC70, HSP70, meristem, SGT1, UV-C
* Present address: Laboratoire des Interactions Plantes Micro-organismes (LIPM), UMR CNRS-INRA 2594/441, F-31326 Castanet-Tolosan, France.
Received 5 December 2008; Revised 10 February 2009 Accepted 16 March 2009