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.
