Maize Genetics Cooperation Newsletter vol 81 2007

 

 

Maize quality breeding in Argentina.  II. Determination of lysine and fatty acids by chromatography

--Corcuera, VR; Giraudo, M; Bernaten�, EA; S�nchez Tuero, H; Malcowski, I

 

          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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