Table 1.
Ability of cucurbit phloem sap proteins to increase plasmodesmal SEL and traffic cell to cell
| Phloem exudate proteins
|
Microinjections*
|
||||
|---|---|---|---|---|---|
| Fraction no. | Size range, kDa | Concentration,† μg⋅μl−1 | 10-kDa FITC-dextran | 20-kDa FITC-dextran | 40-kDa FITC-dextran |
| I | 10–20 | 0.05 | 11 (15; 73%) | 11 (15; 73%) | 0 (10; 0%) |
| II | 20–25 | 0.05 | 13 (16; 81%) | 12 (15; 80%) | 0 (10; 0%) |
| III | 25–50 | 0.05 | 11 (14; 79%) | 10 (14; 71%) | 0 (11; 0%) |
| IV | 50–80 | 0.25 | 10 (14; 71%) | 11 (14; 79%) | 1 (10; 10%) |
| V | 80–100 | 0.10 | 10 (15; 67%) | 11 (14; 79%) | 0 (12; 0%) |
| VI | ≥100 | 0.05 | 11 (14; 79%) | 10 (15; 67%) | 2 (12; 17%) |
Size-fractionated proteins and FITC-dextrans were coinjected into mesophyll cells within the cotyledons of C. maxima plants. Control injections performed with LYCH established that the plasmodesmata, within the injection site, permitted rapid and extensive movement of this small membrane-impermeable probe.
Number of injections in which the fluorescently labeled probe moved from the injected cell into the surrounding tissue (total number of injections in each experiment and percent movement given in parentheses). Fluorescence associated with the injected FITC-dextran began to move into neighboring cells upon delivery into the target cell and, within 1-2 min, it had spread to at least 10 cells.
Represents phloem sap protein concentration back-loaded into the microinjection pipette.