Table 3.
PSRP1 Mediates Form-Specific Cell-to-Cell Movement of Small RNA
| Microinjection
|
||
|---|---|---|
| Injected Materiala | Total (n) | Movement [n (%)]b |
| Phloem fraction 7c + 25-nt ssRNA | 13 | 8 (62)d |
| Phloem fraction 10 + 25-nt ssRNA | 8 | 1 (13) |
| Phloem fraction 7 + 25-nt dsRNA (blunt) | 10 | 0 (0) |
| Phloem fraction 10 + 25-nt dsRNA (blunt) | 9 | 1 (11) |
| Phloem-purified PSRP1 + 25-nt ssRNA | 6 | 5 (83)d |
| R-PSRP1c + 25-nt ssRNA | 26 | 20 (80)d |
| R-PSRP1 + 20-kD FITC-dextran | 11 | 11 (100)d |
| R-PSRP1 + 20-kD FITC-dextran + 25-nt ssRNA | 5 | 5/5 (100/100)d |
| R-PSRP1 + CmRINGP RNA (1 kb) | 8 | 0 (0) |
| R-PSRP1 + 25-nt dsRNA (2-nt 3′ overhang) | 5 | 0 (0) |
| R-PSRP1 + 25-nt ssDNA | 14 | 0 (0) |
| BSA + 25-nt ssRNA | 8 | 0 (0) |
| BSA + 25-nt ssDNA | 8 | 0 (0) |
a
Fluorescent probes were as follows: FITC-dextran and RNA probes Alexa Fluor 568 (red) or 488 (green) labeled and injected at 1-μg/μL concentration.
b
Number of injections, and percentage of total injections, in which probe moved from the target cell.
c
Recombinant (R)-PSRP1 was expressed in E. coli, purified, and used in microinjection studies at 1.5 μg/μL. Phloem protein fractions 7 and 10 were used at 0.1 μg/μL.
d
Movement of the RNA probe (or 20-kD FITC-dextran) was restricted to neighboring cells, and the small RNA signal very often accumulated in their nuclei.