Maize Genetics Cooperation Newsletter vol 86
2012
CHISINAU, MOLDOVA
Institute of Genetics and Physiology of
Plants
Combinative properties of maize
double haploids
--Mikhailov, ME; Maslobrod SN; Sarmaniuc
M.
The combinative capacity of the double haploid (DH)
lines derived from the maize hybrids MK01 x A619 and Rf7 x Ku123 has been
tested. In DH lines genes from both the parents are combined at random, so
their combinative capacity varies and depends on number of favorable alleles
obtained from each parent.
We tested combinative capacity of grain yield in DHxP
crosses. This calculated parameter was used for analysis:
were M is grain yield of the genotype indicated in brackets. Grain yield
of parents and F1 was as follow (gm/plant at the density 4/m2):
2010 year: MK01 - 100.8�5.6, A619 - 22.4�4.4,
MK01xA619 - 181.6�5.4
2011 year: Rf7 - 105.6�5.2, Ku123 - 76.7�3.4,
Rf7xKu123 - 191.9�4.2.
We name the C(P1)
parameter as combinative capacity of the DH line relatively the P1
parent. It shows the increase in grain yield which gives the DH line compared with
increase, which gives the P1 line (in crosses with the same line P2).
The value of C (P1) depends on the
number of favorable alleles inherited by DH line from P1. The distribution of the DH
lines by values of C is shown in
Fig.1-4. The general statistics are given in Table.
In the absence of non allelic interactions (additive-dominant model) C should be distributed symmetrically
about the value of 0.5. In fact, only C(Ku123)
is distributed symmetrically, otherwise C
are less than 0.5, and in two cases significantly (see Table). This suggests significant
role of non allelic interactions of complementary type between the favorable
alleles of the lines MK01 and Rf7.
Non allelic interactions are not significant in the case of A619 and absent
in the case of Ku123. Apparently,
in these cases gene effects are summarized to additive-dominant model.
In Fig.1-4 the differences in the excess are clearly visible. The
distributions of C(MK01) and C(Rf7) have the sharp peaks. In the
distributions of C(A619) and C(Ku123) the peaks are less expressive.
Sharpness of the peak should depend on the number of genetic factors affecting C. The more genetic factors, the sharper
the peak. The number of genetic factors can be estimated from Castel-Wright. In
our case, it looks like this:
N = 0.25 / (σ2-e2), where N is number of genetic factors, σ2 is variance of C, e2
is mean square error of partial value of C.
The estimations are given in Table. Under the assumption that the degree of
dominance is equal to 1, these estimations mean the number of favorable alleles
(or groups of linked alleles) in the corresponding line, responsible for
heterosis of grain yield in crosses.
In both the studied hybrids the same phenomenon is observed. More
productive parent has more alleles influencing heterosis, and significant non allelic
interactions appear between them. In less productive parent number of favorable
alleles is smaller and non allelic interactions between them are less significant
or absent.
Table. Relative combinative capacity of DH lines
|
Hybrid |
Parameter |
Number of DH lines |
Mean C |
Standard deviation of C |
Mean error of partial C |
Estimated number of
genetic factors |
|
MK01 x A619 |
C(MK01) |
41 |
0.387�0.021*** |
0.135 |
0.059 |
16 |
|
C(A619) |
42 |
0.442�0.030 |
0.192 |
0.101 |
9 |
|
|
Rf7 x Ku123 |
C(Rf7) |
26 |
0.378�0.027*** |
0.137 |
0.049 |
15 |
|
C(Ku123) |
25 |
0.489�0.044 |
0.220 |
0.096 |
6 |
*** Difference from 0.5 is significant at
P<0.001
Number
of
Expected
DH lines
mean
│ │
13 ┼ ┌────┤
12 ┼ │ │
11 ┼ ┌────┤ │
10 ┼ │ │ │
9 ┼ │ │ │
8 ┼ │ │ │
7 ┼ ┌────┤ │ │
6 ┼ │ │ │ ├────┐
5
┼ │ │ │ │ │
4
┼ │ │ │ │ │
3
┼ │ │ │ │ │
2
┼ ┌────┤
│ │ │ ├────┐
1
┼────┤
│ │ │ │ │ │
└────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴
C(MK01)
0-0.1 0.1-0.2 0.2-0.3 0.3-0.4 0.4-0.5 0.5-0.6 0.6-0.7 0.7-0.8 0.8-0.9 0.9-1.0
Fig.1. Distribution of DH lines from
combinative capacity relatively MK01 (in crosses with A619)
Number of
Expected
DH lines
mean
│
│
10 ┼
┌────┐ │
9
┼
┌────┤ │ │
8
┼
│
│
│
│
7
┼
│ │ │ │
6
┼
│
│ ├────┼────┐
5
┼
│
│ │ │ │
4
┼
│
│
│
│ ├────┐
3
┼ ┌────┤ │ │ │ │ │
2
┼ │ │ │ │ │ │ │ ┌────┐
1 ┼ │ │ │ │ │ │ ├────┤ ├────┐
└────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴
C(A619)
0-0.1
0.1-0.2 0.2-0.3 0.3-0.4 0.4-0.5 0.5-0.6 0.6-0.7 0.7-0.8 0.8-0.9 0.9-1.0
Fig.2. Distribution of DH lines from
combinative capacity relatively A619 (in crosses with MK01)
Number
of
Expected
DH lines mean
│
│
11 ┼
┌────┐ │
10 ┼
│
│ │
9
┼
│ │ │
8
┼
│ ├────┤
7
┼ │ │ │
6
┼
│ │ │
5
┼
│ │ │
4
┼
│ │ │
3
┼
┌────┤ │ │
2
┼ │ │ │ ├────┐
1
┼────┐ │ │ │ │ │ ┌────┐
└────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴
C(Rf7)
0-0.1
0.1-0.2 0.2-0.3 0.3-0.4 0.4-0.5 0.5-0.6 0.6-0.7 0.7-0.8 0.8-0.9 0.9-1.0
Fig.3. Distribution of DH lines from
combinative capacity relatively Rf7 (in crosses with Ku123)
Number of
Expected
DH lines
mean
│
│
5
┼
┌────┐ ├────┐
4
┼
│ │ │ ├────┐
3
┼ ┌────┤ ├────┤ │ │
2
┼ ┌────┤ │ │ │ │ │ ┌────┐
1
┼ │ │ │ │ │ │ │
┌────┤ │
└────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴
C(Ku123)
0-0.1
0.1-0.2 0.2-0.3 0.3-0.4 0.4-0.5 0.5-0.6 0.6-0.7 0.7-0.8 0.8-0.9 0.9-1.0
Fig.4. Distribution of DH lines from
combinative capacity relatively Ku123 (in crosses with Rf7)
Please
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