Identification and characterisation of cultivar-specific 22-kDa heat shock proteins from mitochondria of Pisum sativum

Pea plants (Pisum sativum L. cv. Feltham First) exposed to a heat stress of 37 degrees C for 6 h accumulated two low molecular weight (LMW) heat shock proteins (HSPs) of molecular mass 22 kDa. The two LMW HSPs were associated with purified mitochondria. N-terminal amino acid sequencing analysis indicates that the more basic of these proteins is a novel protein. The response of other cultivars of P. sativum to heat shock revealed that up to three 22-kDa HSPs were expressed in a cultivar-specific manner. Evidence presented suggests that the different 22-kDa HSPs arise as a result of there bring multiple 22-kDa HSP genes. The expression of the most basic novel HSP was studied in the Feltham First cultivar using two dimensional SDS-PAGE. Treatment of intact plants with chloramphenicol and cycloheximide prior to heat stress treatment indicated that the LMW HSPs were nuclear encoded and de novo synthesised.