CelS : a novel endoglucanase identified from <i>Erwinia carotovora</i> subsp. <i>Carotovora</i>

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Induction of homologous low temperature and ABA-responsive genes in frost resistant (Solanum commersonii) and frost-sensitive (Solanum tuberosum cv. Bintje) potato species

Leonardo A. Meza-Zepeda. Vegetal Biochemical Laboratory, Biological Science Department, University of Talca, 2 Norte 685, Talca, ChileA DNA fragment corresponding to a low-temperature- and ABA-responsive gene (Scdhn1) was amplified by PCR from genomic DNA of a wild, frost-resistant potato species, Solanum commersonii. A homologous gene (Stdhn1) was identified in Solanum tuberosum cv. Bintje, a frost-sensitive domesticated potato cultivar. The expression of the gene was studied during low temperature and ABA treatments in both Solanum species. The analysis revealed that both low temperature and ABA lead to the accumulation of a 1 kb transcript that corresponded to the PCR fragment. The induction of the gene was relatively rapid and maximum amounts of the transcripts were detected already after 1 day and 7 h of treatment with low temperature and ABA, respectively. Previous results have shown that there is no increase in the amount of endogenous ABA in S. tuberosum during low-temperature treatment, which indicates that two independent signalling pathways lead to the induction of this gene

Characterisation of Pectobacterium wasabiae and Pectobacterium carotovorum subsp. carotovorum isolates from diseased potato plants in Finland

To identify bacteria causing soft rot and blackleg in potato in Finland, pectinolytic enterobacteria were isolated from diseased potato stems and tubers. In addition to isolates identified as Pectobacterium atrosepticum and Dickeya sp., many of the isolated strains were identified as Pectobacterium carotovorum subsp. carotovorum. Phylogenetic analysis and biochemical tests indicated that one of the isolates from potato stems resembled Pectobacterium wasabiae. Furthermore, two blackleg-causing P. carotovorum strains recently isolated in Europe clustered with P. wasabiae, suggesting that at least some of these isolates were originally misidentified. All the other Finnish P. carotovorum isolates resembled the subsp. carotovorum type strain in biochemical tests but could be clustered into two distinct groups in the phylogenetic analysis. One of the groups mainly contained strains isolated from diseased tubers, whereas the other mainly included isolates from potato stems. In contrast to the tuber isolates, the stem isolates lacked genes in Type III secretion genes, were not able to elicit a hypersensitive response in tobacco leaves and produced only small amounts of autoinducers in the stationary phase in vitro. P. wasabiae isolate was able to cause similar amount of blackleg-like symptoms as P. atrosepticum in a field experiment with vacuum-infiltrated tubers, whereas both P. atrosepticum and P. carotovorum isolates reduced emergence and delayed growth more than P. wasabiae. Our findings confirm the presence of P. wasabiae in Finland and show that the Finnish P. carotovorum subsp. carotovorum isolates can be divided into two groups with specific characteristics and possibly also different ecologie