Friday, May 22, 2015

Gene mutation plus sugar gives rise to beefsteak tomatoes

A team of scientists at Cold Spring Harbor Laboratory (CSHL), New York, has identified a set of genes that give rise to super-sized tomatoes.

They have found that a particular mutation is responsible, but it’s also linked to specific sugars.

They believe it will be possible to use this discovery to control the size of a wide range of fruits which contain the same genetic mutation, but not the specific sugars that kick it into action.

Their research paper has been published this week in Nature Genetics.

In its original, wild form the tomato plant produces tiny, berry-sized fruits.

Yet among the first tomatoes brought to Europe from Mexico by conquistador Hernan Cortez in the early 16th century were the huge beefsteaks.

Producing fruits that often weigh in at over a pound, this variety has long been understood to be a freak of nature, but only now do we know how it came to be.

The secret of the beefsteak tomato, CSHL Associate Professor Zachary Lippman and colleagues show, has to do with the number of stem cells in the plant’s growing tip, called the meristem.

Specifically, the team traced an abnormal proliferation of stem cells to a naturally occurring mutation that arose hundreds of years ago in a gene called CLAVATA3. Selection for this rare mutant by plant cultivators is the reason we have beefsteak tomatoes today.

The research more broadly shows that there is a continuum of growth possibilities in the tomato plant, and in other plants – since the CLAVATA pathway is highly conserved in evolution and exists in all plants.

By adjusting the number of sugars on CLAVATA keys, and through other mutations affecting components of the pathway, Lippman and colleagues show it is possible to fine-tune growth in ways that could allow breeders to customize fruit size.

The research discussed in this story was funded by the Gordon and Betty Moore Foundation, the Life Sciences Research Foundation, the Energy Biosciences Institute, DuPont Pioneer, the National Science Foundation, ,and the USDA National Institute of Food and Agriculture.