Water movement between epidermal cells of barley leaves - a symplastic connection?

Using the cell-pressure probe the possibility of symplastic wafer flow betw een cells of the upper epidermis of barley leaves was investigated. Cells a nalysed had either an intact or a more or less damaged cellular environment . Cell damage caused large pressure differentials (0.9 MPa) between damaged and adjacent intact cells. Turgor in cells adjacent to damaged cells decre ased significantly. Turgor decreases were the larger the more the adjacent, damaged cell was leaking (decreases by 2.5-4.4%). In cells surrounded by a patch of leaking cells, turgor decreased the most, by 18.1-20.4%. In contr ast, half-times of water exchange (T-1/2) Of cells were not affected by a d amaged cellular environment. Assuming that in the barley leaf epidermis, pl asmodesmata close at pressure-differentials at or exceeding 0.2 MPa as show n for, other plant cells (The Plant Journal 2, 741-750; Canadian Journal of Botany 65, 509-511), it is concluded that symplastic water dow contributes insignificantly to wafer exchange between cells. Mechanical damage to one individual cell is enough to induce significant turgor changes in neighbour ing cells.