London, Mar 2: The mystery of why roots of a plant grow into the soil and not above it seems to have been solved by scientists. According to a team of British scientists, the reason to when seeds germinate, their roots burrow instead of coming up on the soil surface is down to special hairs that chain the root in the soil and help them grow their way past obstacles.
''The key is in the fuzzy coat of hairs on the roots of plants, we have identified a growth control mechanism that enables these hairs to find their way and to elongate when their path is clear, '' says researcher Prof Liam Dolan from the John Innes Centre in Norwich. Root hairs explore the soil in much the same way as a person would feel their way in the dark. If they come across an obstacle, they grope their way around until they can continue growing in an opening. In the meantime, the plant is held in place as the hairs grip the soil.
The hairs are guided by a clever chemical trick that makes them seek out soil. A protein at the tip of root hairs called RHD2 helps stimulate the uptake of calcium from the soil, boosting growth, the production of more protein and further uptake of calcium.
But when an obstacle blocks the hair's path, or indeed it encounters the surface of the soil, the cycle is broken and growth starts in another location and direction.
The work could help develop new crops to deal with poor soils in developing countries, according to the report published in journal Science.
''The knowledge gained from this research will aid in the breeding of such crops through either conventional breeding techniques or genetic modification,'' the Daily Telegraph quoted Prof Dolan as saying.