'Longer lasting, tastier tomatoes in the offing'

Scientists have identified a gene which plays a crucial role in controlling softening of tomatoes, an advance that may lead to new varieties of the fruit which last longer and taste better.
The tomato (Solanum lycopersicum) is one of the most valuable fruit crops in the world. It also plays an important role in our diet providing valuable vitamins, minerals and health promoting phytochemicals, researchers said.
Plant breeders are working continuously to supply high yielding, better tasting, more nutritious and longer lasting tomato varieties, but some of the best tasting varieties soften rapidly and can have a short shelf life, they said.

Researchers led by Graham Seymour from University of Nottingham in the UK have identified a gene that encodes an enzyme which plays a crucial role in controlling softening of the tomato fruit.
The results could pave the way for new varieties of better tasting tomatoes with improved postharvest life through conventional plant breeding, researchers said.
"To support the tomato industry and further improve consumer satisfaction with new tomato varieties, a major scientific goal has been to identify genes that allow the targeted control of fruit softening without impacting other aspects of ripening," said Seymour.

"Such work would permit excellent fruit flavour and colour development, combined with enhanced shelf life," he said.

In the modern supply chain shelf life is critical. To reduce wastage, this is often extended by developing hybrids that are bred to include natural mutations that slow the whole ripening process, researchers said.
But improving shelf life this way can often have a detrimental effect on flavour and colour, they said.
Researchers identified a gene that encodes a pectate lyase which normally degrades the pectin in the tomato cell walls during ripening.
"In laboratory experiments we have demonstrated that if this gene is turned off, the fruit soften much more slowly, but still show normal changes in colour and the accumulation of taste compounds such as acids, sugars and aroma volatiles," said Seymour.

"Natural variation exists in the levels of pectate lyase gene expression in wild relatives of cultivated tomato and these can be used for conventional breeding purposes. This discovery can provide a means to refine the control of fruit softening in modern tomato cultivars," he said.
The findings were published in the journal Nature Biotechnology.