Australian scientists have discovered the biochemical mechanism that controls ripening in grapes – enabling them to speed up or slow the ripening process.

Chris Davies of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) found that applying brassinosteroids – plant hormones chemically similar to human steroids – to grape skins speeded the ripening of the grapes.

They applied brassinosteroids to the skin of some berries at the first sign of colouration and treated others with brassinazole, a brassinosteroid synthesis inhibitor.

They measured the levels of steroids and degrees Brix in ripening grapes at two-week intervals.

After one month the brassinosteroid berries were 13.4 Brix, compared to 12.7 for the control berries and 11.7 for brassinazole treatments.

‘Brassinosteroids act as a signal to the plant by controlling the expression of a large number of genes. For example they turn off genes controlling photosynthesis in the berries and turn on other genes concerned with cell wall changes and flavour and sugar accumulation,’ said Davies.

While the financial implications of such a process are enormous, Davies remains low-key as to its commercial application.

‘We are open to practical applications. Spraying crops with brassinosteroids would work but is too expensive. We are considering breeding options as a way to synchronise ripening.

The trial results were published in Plant Physiology earlier this year.

Written by Frank Smith