Bulletin

Issue: September 2005

Research in Action

Flowering by design?

The prospect of designer crops that flower when it is most convenient for growers is significantly closer as a consequence of molecular biological research under way at La Trobe University and New Zealand's University of Otago.

Two celebrated plant geneticists - La Trobe plant biologist Dr Tony Gendall, who helped British scientists discover the regulatory effects of cold weather on the flowering time of plants, and New Zealand biotechnology research scientist Dr Richard Macknight, who cloned the flowering time gene that helped make this discovery possible - are now working together to identify similar genes and processes in agricultural crops.

The scientists met at the prestigious UK Government- funded plant research institute in Norwich, UK, the John Innes Centre, in the 1990s, where both worked as members of a team of plant geneticists researching plant reproduction.

It was at the John Innes Centre that Dr Gendall and other members of the British team discovered the extent to which many plants regulate their reproductive seasons from clues in their external environment - among them, cold weather.

It was also here that Dr Macknight cloned and characterised the FCA gene - one of the first flowering time genes ever cloned - which encodes an important regulator of plant flowering.

Since then, the scientists have independently pursued their research interests in the molecular processes that induce plant flowering time, and the genetic and environmental factors that influence these. Their interests have now converged in collaborative research around the challenge of identifying and possibly cloning flowering time genes in agricultural crops.

Dr Macknight recently spent six months as an Associate Fellow at the Institute for Advanced Study at La Trobe, working with Dr Gendall to investigate the molecular mechanisms and reproductive pathways in agricultural plant species such as Medicago truncatula (a close relative of lucerne), rice and ryegrass.

The scientists embarked on a quest for genes in cereal crops that perform regulatory functions similar to the FCA gene in the universal model research plant Arabidopsis - a small annual that is a distant relative of the cabbage, cauliflower and Brussels sprout, produces many seeds and requires vernalisation (exposure to long periods of low temperatures) before it will flower.

They have now identified similar genes in rice and ryegrass that also appear to affect the plants' flowering times; and genetic regulatory pathways in both species that suggest flowering times can be artificially regulated - a desirable outcome in perennial ryegrass because it is widely grown in Europe, North America, Australia and New Zealand as cattle fodder, and has lower nutritional value once it flowers.

'When a plant flowers, it tells us it is going to produce its seed, and one way of improving the quality of ryegrass is by lengthening the flowering time,' says Dr Macknight.

'Potentially the major applications for this would be commercial crops that produce seed. By controlling when they flower, you can dictate when the crops will be harvested, and if you're going to have an earlier flowering time, you might get two seasons in one year, or have a plant that flowers earlier or later.

'What we're really looking for is adjusting the flowering time so it suits local conditions more. You might want a plant that responds well to vernalisation, so you can grow it in areas that have colder winters, or plants that don't respond at all, if you want to grow them in other areas.

'One of the major characters conventional breeding has to breed for is the flowering time, so crops will flower when the growers want them to flower. It's a time-consuming and precise business, so if we are able to identify the genes that contribute to the flowering time, they may be the genes people want to introduce when they're looking for a better type, or just want to add to their variety, but don't know what the genes are.

'What we're hoping to do is show that our genes can be used in a commercially grown crop to affect the flowering time, and the next step is for the primary research institutes or the seed companies who may want to take it further.'

Dr Macknight has returned to his research and teaching work in the Department of Biochemistry at the University of Otago, Dunedin, but the collaboration between the two scientists will continue across the Tasman.