Table 3.
Cell-to-cell movement capacity of cucurbit phloem sap and E. coli-expressed PP2
| Injected material | Microinjections* | Extent of movement |
|---|---|---|
| LYCH | 59 (63; 94%) | 20–30 cells |
| 20-kDa FD | 5 (57; 9%) | 1–4 cells† |
| FITC-CMV-MP | 15 (22; 68%) | 20–30 cells |
| FITC-KN1 | 14 (19; 74%) | 20–30 cells |
| FITC-KN1 (MT6)‡ | 1 (10; 10%) | 2 cells† |
| FITC-PP2 (PS)§ | 22 (28; 79%) | 20–30 cells |
| FITC-PP2 (Ec)§ | 14 (19; 74%) | 20–30 cells |
| PP2 (PS) + 20-kDa FD | 20 (26; 77%) | 20–30 cells |
| PP2 (Ec) + 20-kDa FD | 15 (18; 83%) | 20–30 cells |
| PP2 (PS)¶ + 20-kDa FD | 8 (10; 80%) | 20–30 cells |
| PP2 (PS) + 40-kDa FD | 0 (14; 0%) | 0 cells |
| PP2 (Ec) + 40-kDa FD | 2 (15; 13%) | 2–5 cells† |
| FITC-PP2 (MT1)‡ (Ec) | 7 (13; 54%) | 10–12 cells |
| PP2 (MT1) (Ec) + 20 kDa FD | 6 (13; 46%) | 10–12 cells |
| PP2 (MT1) (Ec) + 40 kDa FD | 0 (10; 0%) | 0 cells |
| PP2 (MT2)‡ (Ec) | 9 (14; 64%) | 20–30 cells |
| PP2 (MT2) (Ec) + 20 kDa FD | 22 (30; 73%) | 20–30 cells |
| PP2 (MT2) (Ec) + 40 kDa FD | 0 (11; 0%) | 0 cells |
In these experiments either FITC-labeled proteins or unlabeled proteins plus FITC-dextrans (FD) were pressure-injected into mesophyll cells within the cotyledons of C. maxima plants. Control experiments included the CMV-MP and KN1 from Z. mays.
Details as in Table 1. Proteins prepared from E. coli (CMV-MP, KN1, and PP2) were back-loaded into the pipette tip at concentrations from 1.5 to 2.0 μg⋅μl−1. PP2 (PS) was used at 1.0 μg⋅μl−1.
When movement of fluorescence was detected, it was usually confined to adjacent cells.
KN1 (MT6) is described in ref. 10. PP2 MT1 and PP2 MT2, proteins in which the N-terminal 77 amino acids and C-terminal 40 amino acid residues were deleted, respectively.
(PS) and (Ec) refer to proteins obtained from cucurbit phloem sap and expressed in E. coli, respectively.
PP2 purified from PS using ovomucoid-acrylic beads was used at a concentration of 0.05 μg⋅μl−1.