Abstract:

Filamentation temperature-sensitive H (FtsH) is an ATP dependent metalloprotease and chaperone identified in many prokaryotes and eukaryotes; its homologs have been identified in many plants. FtsH belongs to a larger family of proteins collectively known as the AAA proteins (ATPases associated with diverse cellular activities). Function studies have revealed an important role for FtsH in stress responses. On the basis of one cDNA-AFLP differential fragment isolated from induced mRNA under drought in the potato （Solanum tuberosum L.） genotype H145 that is diploid with drought tolerance, the full length cDNA of a putative FtsH gene, SoFtsH gene was cloned by rapid amplification of cDNA ends (RACE). The gene consists of 723 bp encoding a predicted protein of 129 amino acids. Sequence analysis revealed that it has two 2Fe-2S ferredoxins, iron-sulfur binding regions. The putative signal-peptide, transmembane regions and the Zn²⁺ binding domain, characteristic of FtsH metalloproteases family, were found in the SoFtsH protein. Alignment and phylogenetic analysis of the amino acid sequence deduced from the fragment and the FtsH sequences of other plants retrieved from GenBank were performed with ClustalX program, which showed that SoFtsH shares high identity (>90%) with FtsH reported in tomato, tobacco and Arabidopsis etc. Transcription level of of SoFtsH was investigated by semi-quantitative RT-PCR and Northern blot, using actin gene as a control. The result showed that the transcript of SoFtsH was significantly enhanced under drought. The different profiles of transcript of SoFtsH gene were detected under continuous drought between drought tolerant H145 and drought sensitive H214 that is susceptive to drought. The results suggest that SoFtsH gene is closely related with the drought tolerance in potato.

Key words: Potato, Solanum tuberosum L., Drought tolerance, Full-length cDNA, FtsH