XVI International Botanical Congess

Hsp104 is well known chaperone protein which was shown to have a key role for thermotolerance in yeast. In order to see whether microbial Hsp104 gene can be used for increasing thermotolerance in higher plants, a putative Hsp104 cDNA fragment was isolated from P. sajor-caju by RT-PCR using the primers derived from a conserved region within the Hsp104 genes from various organisms. This cDNA fragment contains an uninterrupted open reading frame of around 3,000 nucleotides which encodes a putative polypeptide of 916 amino acids. Sequence analysis of this gene showed 45% and 38% amino acid sequence homology with those of yeast and soybean Hsp104. Quantitative RT-PCR analysis revealed that the expression of this gene is rapidly induced by heat treatment but not by cold or dry treatment. The complete cDNA of P. sajor-caju Hsp104 was fused to CaMV35S promoter and then introduced into potato plant. Several transgenic potato plants haboring the P. sajor-caju Hsp104 showed constitutive expression of this foreign gene under normal growth condition. Bioassay using these transgenic potatoplants should reveal that whether the microbial Hsp104 gene works for thermotolerance in plant system too.