Abstract

Measurements of respiration rare show char blackcurrant (Ribes nigrum cv. Ben Alder) fruit do not exhibit a respiratory climacteric during ripening, and that ripe fruit produce only very low levels of ethylene. Differential screening of a cDNA library constructed from RNA extracted from blackcurrant fruit enabled the isolation of the cDNA clones of five genes that showed greatly enhanced steady-state transcript levels in fully ripe fruit compared with green fruit. The expression patterns of the corresponding genes were also determined in other tissues of the blackcurrant plant. The sequences of the cDNA clones were compared with known sequences in databases. Four of the clones were identified tentatively on the basis of sequence similarity. pRIB1 was similar co a protein found in the fruit of kiwifruit, pRIB3 was similar to other plant metallothionein-like proteins, pRIB6 to members of the cysteine proteinase family and pRIB7 to a mitochondrial RNA splicing protein. It was not possible to identify pRIB5 on the basis of sequence similarity. Southern analysis indicated that all of these genes were present in the blackcurrant genome at low copy number. Sequences similar to RIB3 and RIB5 are not present in the genomes of red raspberry (Rubus idaeus) or Tayberry (Rubus loganobaccus). The nucleotide sequence data reported appears in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the following accession numbers: AJ007576 (pRIB1), AJ007577 (pRIB3), AJ007578 (pRIB5), AJ007579 (pRIB6) and AJ007580 (pRIB7).