What plants do at night

Plants can adapt their metabolism to make sugars during the hours of darkness.

Two related papers in Science and The Plant Journal by John Innes Centre (JIC) scientists report for the first time the mechanisms inside leaves that are responsible for the conversion of starch into sugars during the night. 'Photosynthesis is well understood, but our discovery is really exciting because it gives us a new insight into how plants control the use of the sugar that they produce,' notes Alison Smith, head of the Metabolic Biology Department at JIC.

The paper published in Science (2004, 303, 87) reports the discovery of a previously unknown maltose transporter (controlled by gene MEX1), in the chloroplast envelope membrane, which allows the chloroplast to export maltose produced by breakdown of starch.

In a related paper, published online in The Plant Journal on 12 January 2004 (DOI: 10.1111/j.1365-313X.2003.0212.x), the same researchers report a cytosolic glucosyltransferase (controlled by gene DPE2) the first step on a novel pathway to convert maltose to sucrose.

These discoveries were made using the plant model Arabidopsis, whose genome sequence was published in 2000, illustrating how such sequences are now being used to unravel vital biological processes.

Hamish Kidd