Acquired thermotolerance and expression of the HSP100/ClpB genes of lima bean.
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.
Keeler
S J
SJ
Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19717, USA. sharon.j.keeler@usa.dupont.com
Boettger
C M
CM
Haynes
J G
JG
Kuches
K A
KA
Johnson
M M
MM
Thureen
D L
DL
Keeler
C L
CL
Kitto
S L
SL
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
D006360:Heat-Shock Proteins; D015800:Protozoan Proteins; D049071:Endopeptidase Clp; C095049:ClpB protein, Leishmania