Improved germination under osmotic stress of tobacco plants overexpressinga cell wall peroxidase

The cell wall is a fundamental component in the response of plants to envir onmental changes. To directly assess the role of the cell mall we have incr eased the expression and activity of a cell wall associated peroxidase (TPX 2), an enzyme involved in modifying cell wall architecture. Overexpression of TPX2 had no effect on nild-type development, but greatly increased the g ermination rate under high salt or osmotic stress, Differential scanning ca lorimetry showed that transgenic seeds were able to retain more water avail able for germination than wild-type seeds, Thermoporometry calculations ind icated that this could be due to a lower;er mean pore size in the malls of transgenic seeds, Therefore, the higher capacity of transgenic seeds in ret aining water could result in higher germination rates in conditions where t he availability of water is restricted. (C) 1999 Federation of European Bio chemical Societies.