title: Acquired thermotolerance and expression of the HSP100/ClpB genes of lima bean.
abstract: Acquired thermotolerance (AT) is the ability of cells to survive a normally lethal temperature treatment as a consequence of pretreatment at an elevated but sublethal temperature. In yeast and cyanobacteria, the expression of the HSP100/ClpB protein is required for the AT response. To determine whether the HSP100/ClpB protein is associated with this response in lima bean (Phaseolus lunatus), we have cloned an HSP100/ClpB homolog and assessed expression of the two gene copies under heat stress conditions, which induce AT. Transcription of the cytoplasmically localized HSP100/ClpB protein genes is stringently controlled by heat stress in both of the laboratory and field heat stress conditions. From a heat-induced cDNA library, we identified a clone of a putative chloroplast-targeted (cp) HSP100/ClpB protein gene sequence. The cp HSP100/ClpB protein genes are constitutively expressed, but transcript levels increase post-heat stress in laboratory heat stress experiments. In field conditions the genes for the cp HSP100/ClpB are constitutively expressed. Although we were unable to correlate differences in the timing of AT response with the expression or genetic structure of the HSP100/ClpB genes in heat-tolerant or -sensitive varieties of lima bean, we clearly demonstrate the association of expression of HSP100/ClpB proteins with heat response in this species.
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19717, USA. sharon.j.keeler@usa.dupont.com
authors.forename: S J
authors.initials: SJ
authors.lastname: Keeler
authors.forename: C M
authors.initials: CM
authors.lastname: Boettger
authors.forename: J G
authors.initials: JG
authors.lastname: Haynes
authors.forename: K A
authors.initials: KA
authors.lastname: Kuches
authors.forename: M M
authors.initials: MM
authors.lastname: Johnson
authors.forename: D L
authors.initials: DL
authors.lastname: Thureen
authors.forename: C L
authors.initials: CL
authors.lastname: Keeler
authors.forename: S L
authors.initials: SL
authors.lastname: Kitto
mesh_terms: D000595:Amino Acid Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D049071:Endopeptidase Clp; D007887:Fabaceae / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D006358:Hot Temperature; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010946:Plants, Medicinal; D016133:Polymerase Chain Reaction; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D006360:Heat-Shock Proteins; D015800:Protozoan Proteins; D049071:Endopeptidase Clp; C095049:ClpB protein, Leishmania