Plenty of scope for new gene discovery

What does a scientist do when he has a really interesting gene with blockbuster potential, but no clue about its function?

Assoc Prof Jimmy Botella, head of the plant genetic engineering laboratory at the University of Queensland, and his team have discovered a gene in Arabidopsis they call Plentiful, because transgenic plants are more compact with more branches, more leaves, more flowers and seeds, more root structures. The plants also have leaves of a deeper green and develop more slowly during the vegetative stage, outlasting their non-transgenic counterparts. In short, the gene really does make the whole plant more plentiful.

The applications of such a gene in agriculture and horticulture are potentially enormous, according to Botella, who envisages dense, slow-growing turf grasses, higher yielding seed, fruit and vegetable crops and more blooms per stem for ornamental flowers.

"It alters development, appearance and architecture, all with only one gene," he said.

But here's the catch -- Plentiful has no known function, in fact it doesn't contain a single known motif. The researchers are now using a range of techniques to study the gene, hoping to tease out its function, including genomics and proteomics, light and electron microscopy and hormone studies.

"I'm not quite sure of its cellular role, but I'm extremely sure of its phenotypic effects," said Botella. There is evidence that something is going on with cell elongation processes, as well as cell division, but the wild-type gene appears to be active only in the roots and leaves, compared to the transgene which is expressed everywhere. His suspicion is that the gene is a modulator.

"The next thing I would like to do is knock it out," he said. But this may be difficult to achieve, he concedes, as the researchers have already had problems down-regulating it using RNA interference, suggesting that knockouts might be lethal.

Plentiful appears to be restricted to plants from the searches Botella has carried out to date. "We have found homologues in two other plant EST projects, so it appears to be widespread," he said. And without giving away the species of the homologues, he says they are quite distant from Arabidopsis.

Botella is also looking for commercial partners interested in putting the gene to use. The gene has already had an Australian patent granted, and other patent applications are in progress.

But meanwhile, the researchers will keep working on the problem of the Plentiful gene. The gene was discovered by the researchers as part of a gene discovery project examining ESTs of 90 uncharacterised genes, which were used to create 1800 transgenic lines. "These kind of studies can take years and hundreds of plants," said Botella.