Table 1.
NaCl tolerance of transformed tobacco plants genetically cosegregates with the yeast CaN transgenes
| Line | Plants
|
Knr:Kns segregation ratio
|
||
|---|---|---|---|---|
| Initial, n | Survival, % | Before NaCl shock | After NaCl shock | |
| Experiment 1 | ||||
| PKY | 107 | 36.4 (27–45)* | 3:1 | 2.5:1 |
| W38 | 54 | 37.0 (24–50) | — | — |
| A2 | 49 | 74.0 (61–85) | 15:1 | ND |
| A9 | 36 | 69.4 (54–84) | 15:1 | ND |
| C8 | 51 | 82.4 (71–93) | 3:1 | ND |
| F3 | 56 | 75.0 (64–86) | 3:1 | ND |
| T7 | 81 | 64.2 (54–74) | 3:1 | 9.4:1† |
| Experiment 2 | ||||
| PKY | 120 | 24.1 (16–32) | 3:1 | ND |
| A9 | 36 | 77.7 (64–92) | 15:1 | ND |
| T7 | 115 | 53.4 (44–62) | 3:1 | 11.2:1‡ |
Seedlings of an untransformed tobacco line (W38), and first-generation progeny from self-pollinations (T1) of a line expressing only the neomycin phosphotransferase-selectable marker gene npt-II (PKY), effecting kanamycin resistance (Knr), and lines expressing CNAtr and CNB in addition to NPT-II (A2, A9, C8, F3, and T7) were evaluated. Experiment 1: Seedlings grow in plant tissue culture raft vessels. T1 tobacco seedlings were transferred to mineral nutrient solution containing 250 mM NaCl. After 4 days of salt shock, seedlings were transferred to nutrient solution without NaCl and left to recover for 10 days. Seedlings remaining viable after this period were evaluated for sensitivity (Kns) or resistance (Knr) to kanamycin and NPT-II activity. Presented are the percentages, of each population, surviving NaCl treatment (Survival) and the Knr:Kns ratio of the population before and after NaCl shock treatment. Experiment 2: Plants grown in hydroponic culture in a plant growth chamber. Hydroponically grown T1 progeny of lines PKY, A9, and T7 were transferred to fresh mineral nutrient (1/4× MS) solution containing 200 mM NaCl. After 7 days, the plants were transferred to solution without NaCl. Ten days subsequently, the number of surviving plants was determined. Knr:Kns of the T7-derived plants, after NaCl shock, was assessed by using the NPT-II assay. ND, not determined.
Confidence intervals (95%) for a binomial distribution/proportion.
Different from the expected 3:1 values at 95% level.
Different from the expected 3:1 values at 99% level.