When flooded by water, some plants rapidly send up shoots above the surface and use the new leaves as a kind of ‘snorkel’. A team of Dutch biologists led by Dr Rens Voesenek (Nijmegen University) are to investigate the way plants control this adaptive behaviour. It is hoped that the insights gained will ultimately make it possible to select crops which can cope with floods and high water levels. Funding for the project will take the form of a PIONEER subsidy from NWO.
When a plant is submerged during a flood, the level of ethylene gas in the plant rises and the concentration of oxygen falls. So as not to ‘drown’, certain plants use rapidly growing new shoots as a means of channelling life-saving oxygen through the stalks and roots to their root tips. Up to now, it has been unclear why certain species are capable of triggering this adaptive reaction while other closely related ones are not.
The Dutch biologists hope to unravel this process of underwater growth at the physiological and molecular level. It is clear that the plant perceives the change from air to water and that ethylene and the receptor of this gas on the cell membrane play a role in its doing so. Various hormones evidently give the alarm to various parts of the plant so that the cells can react by accelerating their longitudinal growth and producing the life-saving shoots.
Differences in the capacity to adapt to flooding have a major impact on the natural distribution of plants in low-lying river areas. In such areas in the Netherlands, some species can only be found in locations which are rarely flooded, for example dikes and embankments, whereas other species can be found outside the dikes in low-lying areas which are frequently flooded.
Source: Netherlands Organization For Scientific Research, April 1999