Maize Genetics Cooperation Newsletter vol 81 2007
Within the last decade at the Instituto Fitotecnico Santa Catalina and CIGEN located in Llavallol, a province of Buenos Aires, Argentina (22 m.a.s., 34� 48�S; 58� 31�W), a maize quality breeding program has been underway. Normal genotypes previously developed in Argentina were reconverted to quality protein maize through the incorporation of the o2, o5, o11 or o12 genes from Illinois and Bergamo inbreds used as donors. Lysine content in endosperm flour of three inbreds and a single cross has been determined via rp-HPLC. Simultaneously, the germ fatty acid composition of 4 inbreds and three single crosses were analyzed through gas chromatography.
Normally,
maize has only 0.3% lysine in endosperm flour, but the expression of the o2 gene can double or treble it. High lysine contents were found in the
first inbreds studied (3088: 1.3%; 3098: 0.9% and 3139 II: 0.6%). These inbreds have a
high oil content as previously detected by NIR using an Isotec 1227
device (3088: 5.8%; 3098: 6.0% and 3139 II: 7.3%). Also, the single cross 3152, obtained by crossing one of
these inbreds as female x a wx1 o2
double recessive male, was a complete success in relation to its high lysine
content (0.7%). This hybrid has a
good agronomic performance as demonstrated through its average yield during
three years running in multilocation trials (9,100 kg/ha). The fatty acid composition of the
different genotypes studied may be seen in Tables 1 to 3. Generally, the endosperm of maize without
expression of single mutant genes has a composition of 60% linoleic acid and 20
to 27% oleic acid (3:1 ratio). In
the case of the high lysine and double recessive wx1 o2 genotypes analyzed, we found a 1.3:1 to 2.2:1 ratio between
linoleic and oleic acid. The
narrower
Table 1. Fatty acid composition in single mutant gene
inbreds.
|
|
|
% content
|
|
|
Fatty acid |
3115* |
3016b** |
|
|
16:0 |
Palmitic |
10.04 |
7.47 |
|
16:1 |
Palmitoleic |
1.25 |
0.21 |
|
18:0 |
Stearic |
2.44 |
1.05 |
|
18:1 |
Oleic |
32.16 |
35.25 |
|
18:2 |
Linoleic |
42.85 |
50.18 |
|
18:3 |
Linolenic |
1.04 |
0.8 |
|
20:0 |
Arachidic |
0.56 |
0.53 |
|
20:1 |
Arachiidonic |
0.32 |
0.4 |
|
22:0 |
Behenic |
0.39 |
0.41 |
|
22:1 |
Erucic |
0.32 |
0.21 |
|
24:1 |
Lignoceric |
1.37 |
0.95 |
|
*o11 inbred |
**wx1 inbred |
|
|
Table 2. Fatty acid composition in single-cross hybrids.
|
|
|
% content |
|
|
Fatty acid |
3165* |
3166** |
|
|
16:0 |
Palmitic |
9.36 |
12.83 |
|
16:1 |
Palmitoleic |
1.05 |
no data |
|
18:0 |
Stearic |
2.68 |
3.77 |
|
18:1 |
Oleic |
33.2 |
27.49 |
|
18:2 |
Linoleic |
52.2 |
38.36 |
|
18:3 |
Linolenic |
0.33 |
no data |
|
20:0 |
Arachidic |
0.68 |
no data |
|
20:1 |
Eicosenoic |
no data |
no data |
|
22:0 |
Behenic |
1.06 |
no data |
|
22:1 |
Erucic |
0.64 |
no data |
|
24:1 |
Lignoceric |
4.54 |
no data |
|
*wx1
o2 |
**waxy |
|
|
Table 3. Fatty
acid composition of a single-cross and its parents.
|
|
|
% content |
||
|
Fatty acid |
3096b* |
3135** |
3257 |
|
|
14:0 |
Myristic |
3.00% |
0.04 |
0.03 |
|
16:0 |
Palmitic |
8.66 |
12.25 |
9.46 |
|
16:1 |
Palmitoleic |
0.09 |
0.09 |
0.08 |
|
17:0 |
Heptadecanoic |
0.06 |
0.1 |
0.05 |
|
18:0 |
Stearic |
2.03 |
1.8 |
1.56 |
|
18:1 |
Oleic |
35.84 |
25.12 |
28.53 |
|
18:2 |
Linoleic |
45.13 |
55.45 |
55.87 |
|
18:3 |
Linolenic |
0.94 |
0.82 |
0.8 |
|
20:0 |
Arachidic |
0.54 |
0.35 |
0.58 |
|
*wx1
o2 female parent |
**wx1
o2 male parent |
|
||
ratio (1.3:1) was expressed by the o11 mutant inbred 3115. All inbreds and single cross hybrids studied showed very low levels of eicosenoic and linolenic acid. The levels of myristic, palmitic, heptadecanoic and arachidic acids found in the single cross 3257 (see Table 3), obtained after crossing the inbreds 3096b (♀) x 3135a (♂), show maaternal inheritance. In contrast, the levels of oleic, linoleic and linolenic acids are paternally inherited. On the other hand, the stearic acid content of the hybrid does not differ significantly from the mid-parent value, showing additive inheritance.
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