Maize
Genetics Cooperation Newsletter 80. 2006.
Institute of Genetics
Forty-five double haploid (DH) lines of maize derived from a MK01 x A619 hybrid were tested for quantitative traits in 2003-2005. Forty lines were tested in all three years, 5 lines in one or two years. These lines were obtained by colchicine doubling haploids that were produced by pollinating the F1 with Moldavian Haploid Inducer (MHI). Therefore, the genome of the DH lines is the doubed genome of female gametes of the F1. Genes of both parents are presented in various combinations in the set of DH lines except for heterozygotes.
In accordance with an additive-dominant model, the distribution of the DH lines for a quantitative trait would be symmetric around midparent values (the mean of MK01 and A619): half of the DH lines would be above midparent values and the other half would be below. In reality, some traits (productivity, ear diameter, number of kernels, number of ears, time of flowering and maturity) show stable asymmetry (see Table 1). This suggests the important role of non-allelic interactions in the genetic control of these traits.
Table
1. Distribution of DH lines
relative to midparent.
|
Trait |
Distribution ratio of the DH lines (above : below) |
||
|
2003 |
2004 |
2005 |
|
|
Time of tassel flowering |
4:37
** |
9:35
*** |
6:38
*** |
|
Tine of silk flowering |
6:34
** |
9:35
*** |
5:39
*** |
|
Anthesis-silking interval |
24:16 |
19:25 |
19:25 |
|
Flowering-maturity interval |
15:24 |
14:30
* |
30:14
* |
|
Time of maturity |
10:30
** |
9:35
*** |
14:30
* |
|
Height of plant |
7:34
*** |
7:37
*** |
20:24 |
|
Length of steam |
5:36
*** |
8:36
*** |
21:23 |
|
Length of tassel |
21:20 |
22:22 |
13:31* |
|
Diameter of steam |
15:26 |
21:23 |
14:30
* |
|
Number of nodes |
7:34*** |
13:31*** |
21:23 |
|
Number of ears |
12:29
* |
14:30
* |
11:33
** |
|
Weight of cob |
15:26 |
19:25 |
19:25 |
|
Length of ear |
10:31
** |
18:26 |
10:34
*** |
|
Diameter of ear |
3:38
*** |
4:39
*** |
6:38
*** |
|
Number of kernel rows |
17:24 |
15:28 |
10:33
*** |
|
Number of kernels |
4:37
*** |
6:38
*** |
15:29
* |
|
Weight of 1000 kernels |
23:17 |
19:24 |
24:20 |
|
Productivity of first ear |
3:38
*** |
6:38
*** |
14:30
* |
|
Productivity of second ear |
6:35
*** |
12:32
** |
10:34
*** |
|
Total productivity |
2:39
*** |
6:38
*** |
14:30
* |
Comment. Disagreement with 1:1 ratio *P<0.05, **P<0.01,
***P<0.001.
Apparently,
genetic interactions in some traits (weight of cob, weight of 1000 kernels,
anthesis-silking interval, length of tassel, diameter of steam) are mainly
additive and dominant.
Distribution of other traits is intermediate or unstable.
_________________________________________________
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note:
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