In a previous study, a 65 kDa protein, TDI-65, was found to be accumulated in the leaves of drought-stressed tomato (Lycopersicon esculentum cv. Starfire) plants. The protein level returns to control level when the drought-stressed plants are rewatered. Antibodies raised against the purified protein were used to elucidate the subcellular localization of the protein. The protein was found to be mainly localized in the nuclei and chloroplasts of drought-stressed leaf cells. To identify the nature of the protein, a cDNA library was constructed and screened by the purified anti-TDI-65 antibody. A cDNA clone designated tdi-65 was isolated and characterized. The deduced amino acid sequences of tdi-65 protein has extensive homology with known cysteine proteases such as actinidin and papain. Northern blot analysis revealed that tdi-65 mRNA is 10-fold higher in drought-stressed plants as compared to control and rewatered plants. Similar results were observed in the tomato cultivar Ailsa and its near isogenic abscisic acid (ABA)-deficient mutant line, flacca, suggesting that the gene does not require ABA for its expression under drought conditions. Based on the previous immunolocalization findings we suggest that tdi-65 encoded cysteine protease functions in relation to drought-induced senescence and programmed cell death.

Twenty-two isolates of Pectobacterium carotovorum were collected from soft-rotted potato tubers originating from different production areas in Morocco, and their phenotypic and genetic characteristics were investigated. All of the isolates were identified as P. carotovorum by API 20E (identification kit) system, and yielded a 434-bp DNA fragment of the pectate-lyase-encoding pel gene in PCR experiments. Collected strains were also evaluated for their susceptibility to 11 different antibiotics: Sulfamethoxazole/ trimethoprim (SXT), Ceftazidime (CAZ), Ciprofloxacin (CIP), Cefotaxime sodium (CTX), Imipenem (IPM), Gentamicin (CN), Amikacin (AK), Colistin sulphate (CT), Netilmicin (NET), Ampicillin (AMP) and Cephalothin (KF). Of the total P. carotovorum strains isolated, 5 were resistant to only two antibiotics: Ampicillin and Cephalothin. Evaluation of genetic diversity was performed on all isolates by molecular typing with Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR). Results showed the isolates to be distributed on 2 major clusters subdivided into many subclusters. The genetic diversity within the potato strains of P. carotovorum subspecies is shown. No correlation between ERIC-PCR analyses, suscebtibility patterns, geographic areas and year isolated was observed. These results may indicate that the tuber could be the main source of contamination. In conclusion, the ability to distinguish Pectobacterium carotovorum strains from diseased potato with PCR based assay will be useful for strain relatedness studies of this pathogen in Morocco.

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