Mh. Harpster et al., Expression analysis of a ripening-specific, auxin-repressed endo-1,4-beta-glucanase gene in strawberry, PLANT PHYSL, 118(4), 1998, pp. 1307-1316
A cDNA (Cel1) encoding an endo-1,4-beta-glucanase (EGase) was isolated from
ripe fruit of strawberry (Fragaria x ananassa). The deduced protein of 496
amino acids contains a presumptive signal sequence, a common feature of ce
ll wall-localized EGases, and one potential N-glycosylation site. Southern-
blot analysis of genomic DNA from F. x ananassa, an octoploid species, and
that from the diploid species Fragaria vesca indicated that the Cell gene
is a member of a divergent multigene family. In fruit, Cell mRNA was first
detected at the white stage of development, and at the onset of ripening, c
oincident with anthocyanin accumulation, Cell mRNA abundance increased dram
atically and remained high throughout ripening and subsequent fruit deterio
ration. In all other tissues examined, Cell expression was invariably absen
t. Antibodies raised to Cell protein detected a protein of 62 kD only in ri
pening fruit. Upon deachenation of young white fruit to remove the source o
f endogenous auxins, ripening, as visualized by anthocyanin accumulation, a
nd Cell mRNA accumulation were both accelerated. Conversely, auxin treatmen
t of white fruit repressed accumulation of both Cell mRNA and ripening. The
se results indicate that strawberry Cell is a ripening-specific and auxin-r
epressed EGase, which is regulated during ripening by a decline in auxin le
vels originating from the achenes.