Plants hold secret of gravity in their sway

By David Derbyshire in San Francisco for The Daily Telegraph (London)

SCIENTISTS have discovered how plants spring back so quickly after being knocked over by wind or trampled by a careless foot.

A study into maize and oats has shown that plants use a chemical also present in the human brain to "perceive" almost instantly that something is amiss and then bend in the right direction within minutes or hours. The findings help to explain how gravity affects plant growth and could have implications for attempts to grow food in space.

Dr Wendy BOss, of North Carolina State University, said: "If humans are going to go on sustained space missions, we'll need to use plants to turn carBOn dioxide into oxygen, to cleanse water and to provide food. Before we create such long-term life-support systems, we need to know how gravity affects the growth of plants."

Scientists do not know how plants will react to the lack of gravity in space. They use gravity to move nutrients, water and sugars between their roots and shoots. Dr BOss and colleagues studied inositol trisphosphate (InsP3), a molecule used by plants and human brains to transmit chemical signals.

They found that within 15 seconds after an oat or maize plant was placed on its side, the amount of InsP3 surged fivefold in the pulvinus, a part of the stem causing a plant to bend upward after falling. Dr BOss reckons the pulvinus cells are communicating aBOut whether the plant is upright.

The signalling lasted aBOut 30 minutes in oats and up to four hours in maize, allowing the plant to determine whether it has been knocked to the ground or is swaying in the wind.