CLONING AND CHARACTERIZATION OF THE CDNA CLONES OF 5 GENES THAT ARE DIFFERENTIALLY EXPRESSED DURING RIPENING IN THE FRUIT OF BLACK-CURRANT (RIBES NIGRUM L.)

Measurements of respiration rate show that blackcurrant (Ribes nigrum cv. Ben Alder) fruit do not exhibit a respiratory climacteric during r ipening, and that ripe fruit produce only very low levels of ethylene. Differential screening of a cDNA library constructed from RNA extract ed from blackcurrant fruit enabled the isolation of the cDNA clones of five genes that showed greatly enhanced steady-state transcript level s in fully ripe fruit compared with green fruit. The expression patter ns of the corresponding genes were also determined in other tissues of the blackcurrant plant. The sequences of the cDNA clones were compare d with known sequences in databases. Four of the clones were identifie d tentatively on the basis of sequence similarity, pRIB 1 was similar to a protein found in the fruit of kiwifruit, pRIB3 was similar to oth er plant metallothionein-like proteins, pRIB6 to members of the cystei ne proteinase family and pRIB7 to a mitochondrial RNA splicing protein . It was not possible to identify pRIB5 on the basis of sequence simil arity. Southern analysis indicated that all of these genes were presen t in the blackcurrant genome at low copy number. Sequences similar to RIB3 and RIB5 are not present in the genomes of red raspberry (Rubus i daeus) or Tayberry (Rubus loganobaccus). The nucleotide sequence data reported appears in the EMBL, GenBank and DDBJ Nucleotide Sequence Dat abases under the following accession numbers: AJ007576 (pRIB1), AJ0075 77 (pRIB3), AJ007578 (pRIB5), AJ007579 (pRIB6) & AJ007580 (pRIB7).