We have reported that crosses between 11 inbred lines and the c-ruq
tester
only produced colorless no-spot F1 kernels, indicating a lack of any active
Uq
elements in these inbreds (MNL 61:5). In order to determine if there
are any Uq activation events as reported by the c-ruq reporter
allele, random samples of the colorless no-spot F1 kernels were taken from
7 inbred x c-ruq combinations. These kernels were grown and were
tested by backcrossing to the c-ruq tester. The resulting BC1 progeny
ears have been examined to generate the accompanying data.
| Total number of colorless BC1 progeny kernels | ||||
| Inbred | Number of F1 kernels testeda | no-spot | few-spot (%) | sectored (%) |
| B14 | 12 | 7,133 | 0 (0) | 0 (0) |
| B37 | 11 | 7,761 | 0 (0) | 0 (0) |
| B73 | 11 | 7,756 | 2 (0.026) | 1 (0.013) |
| B70b | 29 | 11,903 | 2 (0.017) | 3 (0.025) |
| B70 | 21 | 9,880 | 0 (0) | 0 (0) |
| C123b | 24 | 12,692 | 2 (0.016) | 1 (0.008) |
| C123 | 11 | 5,864 | 2 (0.034) | 0 (0) |
| 187-2b | 17 | 9,161 | 1 (0.011) | 1 (0.011) |
| 187-2 | 24 | 14,687 | 2 (0.014) | 0 (0) |
| C103 | 9 | 3,845 | 1 (0.026) | 1 (0.026) |
Activation of Uq elements is seen as sectors of spotting in the BC1 progenies of 5 inbreds (B70, B73, C103, C123 and 187-2) with frequencies ranging from 0.8 x 10-4 to 2.5 X 10-4. No such sectors were observed in the BC1 progenies of the other 2 inbreds (B14 and B37). It is noted that this sectoring of c-ruq/Uq spots occurred in BC1 progenies of 3 inbreds after a 30 µM 5-aza-2'-deoxycytidine treatment, but not in the BC1 generation of their untreated sibs.
This study also indicates a lack of active Uq elements in the genome of the inbred B45, which has a C/C genotype (data not shown). In addition, the BC1 progenies of B45 and 2 other maize lines, M14 (wx) and M14 (Wx), are all colorless, completely lacking single-spots or sectors of spots (data not shown).
Yong-Bao Pan and Peter A. Peterson
Return to the MNL 62 On-Line Index
Return to the Maize Newsletter Index
Return to the MaizeGDB Homepage