Example 6
Ceres cDNA 12723147 encodes an Arabidopsis putative aldo/keto reductase. Ectopic expression of Ceres cDNA 12723147 under the control of the CaMV35S promoter induces the following phenotypes:
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- Germination on high concentrations of polyethylene glycol (PEG), mannitol and abscissic acid (ABA).
- Continued growth on high concentration of PEG, mannitol and ABA.
Generation and Phenotypic Evaluation of T1 Lines Containing 35S::cDNA 12723147.
Wild-type Arabidopsis Wassilewskija (WS) plants were transformed with a Ti plasmid containing cDNA 12723147 in the sense orientation relative to the CaMV35S constitutive promoter. The Ti plasmid vector used for this construct, CRS338, contains PAT and confers herbicide resistance to transformed plants. Ten independently transformed events were selected and evaluated for their qualitative phenotype in the T1 generation. No positive or negative phenotypes were observed in the T1 plants.
Screens of Superpools on High PEG, Mannitol, and ABA as Surrogate Screens for Drought Tolerance.
Seeds from 13 superpools (1,200 T2 seeds from each superpool) from the CaMV35S or 32449 over-expression lines were tested on 3 drought surrogate screens (high concentrations of PEG, mannitol, and ABA) as described above. T3 seeds were collected from the resistant plants and analyzed for resistance on all three surrogate drought screens.
Once cDNA 12723147 was identified in resistant plants from each of the three surrogate drought screens, the five individual T2 events containing this cDNA (SR01013) were screened on high PEG, mannitol, and ABA to identify events with the resistance phenotype.
Superpools (SP) are referred to as SP1, SP2 and so on. The letter following the hyphen refers to the screen (P=PEG, M=mannitol, and A=ABA) and the number following the letter refers to a number assigned to each plant obtained from that screen on that superpool. For example, SP1-M18 is the 18th plant isolated from a mannitol screen of Superpool 1.
Qualitative and Quantitative Analysis of 2 Independent Events Representing 35S::cDNA 12659859 (SR01010) on PEG, Mannitol and ABA
To identify two independent events of 35S::cDNA 12659859 showing PEG, mannitol, and ABA resistance, 36 seedlings from each of two events, SR01013-01 and -02 were screened as previously described. BastaR segregation was assessed to verify that the lines contained a single insert segregating in a 3:1 (R:S) ratio as calculated by a chi-square test (Table 6-1). Both lines (01 and 02) segregated for a single insert in the T2 generation (Table 1)
TABLE 6-1
BastaR segregation for SR01013 individual events
Probability
EventResistantSensitiveTotalof Chi-test*
SR01013-01305350.14323
SR01013-02306360.24821
SR01013-01-3341360.00248**
SR01013-02-2320320.00109**
*Chi-test to determine whether actual ratio of resistant to sensitive differs form the expected 3:1 ratio.
**Significantly different than a 3:1 (R:S) ratio
Lines SR01013-01 and -02 were chosen as the two events because they had a strong and consistent resistance to PEG, mannitol and ABA. The controls were sown the same day and in the same plate as the individual lines. The PEG (Tables 6-2 and 6-3), mannitol (Tables 6-4 and 6-5) and ABA (Tables 6-6 and 6-7) segregation ratios observed for SR01013-01 and -02 are consistent with the presence of single insert as demonstrated by chi-square, similar to what we observed for BastaR resistance (Table 6-1).
The progeny from one resistant T2 plant from each of these two events were tested in the same manner as the T2. Resistance to PEG, mannitol and ABA was also observed in the T3 generation. Taken together, the segregation of resistant seedlings containing cDNA 12723147 from two events on all three drought surrogate screens and the inheritance of this resistance in a subsequent generation, provide strong evidence that cDNA 12723147 when over-expressed can provide tolerance to drought.
TABLE 6-2
Chi-square analysis assuming a 3:1 (R:S) ratio for progeny of
SR01013-01T2 containing 35S::cDNA 12723147 on PEG.
Probability
EventObservedExpectedχ2of Chi-Test
PEG Resistant22270.9260.054
PEG Sensitive1492.778
36363.704
TABLE 6-3
Chi-square analysis assuming a 3:1 (R:S) ratio for progeny of
SR01013-02 T2 containing 35S::cDNA 12723147 on PEG.
Probability
EventObservedExpectedχ2of Chi-Test
PEG Resistant26270.037.700
PEG Sensitive109.111
3636.148
TABLE 6-4
Chi-square analysis assuming a 3:1 (R:S) ratio for progeny of
SR01013-01 T2 containing 35S::cDNA 12723147 on mannitol.
Probability
EventObservedExpectedχ2of Chi-Test
Mannitol Resistant2827.037.700
Mannitol Sensitive89.111
3636.148
TABLE 6-5
Chi-square analysis assuming a 3:1 (R:S) ratio for progeny of
SR01013-02 T2 containing 35S::cDNA 12723147 on mannitol.
Probability
EventObservedExpectedχ2of Chi-Test
Mannitol Resistant18273.0005
Mannitol Sensitive1899
363612
TABLE 6-6
Chi-square analysis assuming a 3:1 (R:S) ratio for progeny of
SR01013-02 T2 containing 35S::cDNA 12723147 on ABA.
EventObservedExpectedχ2Probability
ABA Resistant1324 5.0427.098
ABA Sensitive19 815.125
323220.167
TABLE 6-7
Chi-square analysis assuming a 3:1 (R:S) ratio for progeny of
SR01013-02 T2 containing 35S::cDNA 12723147 on ABA.
EventObservedExpectedχ2Probability
ABA Resistant1324 5.0427.098
ABA Sensitive19 815.125
323220.167
FIG. 5 provides the results of the consensus sequence (SEQ ID NOs: 178-200) analysis based on Ceres cDNA 12723147.