4.2 The objectives of this chapter are
4.6.1 Parents’ GSL profile and content under control conditions
We observed wide variations in total leaf glucosinolate content and in the individual glucosinolates between the parental lines Mansholts and Samourai. This was also the case in the DH population. Mansholts showed higher GSL than Samourai under control and salt stress. Noteworthy is that under salt stress Mansholts showed an increase in total GSL due to the increase in aliphatic GSL.
Mansholts GSL content under control conditions
Under control conditions, the total GSL content of Mansholts was 9.59 µmol/ g DM (Table 7). The aliphatic GSL concentration was 7.6 µmol/ g DM, which accounts for 79% of the total GSL (Table 8). The main compositions were PRO, GBN and GNA.
The concentrations of these components were 4 µmol/ g DM, 2.10 µmol/ g DM and 1.20 µmol/ g DM, respectively. The proportions of these components in the aliphatic GSL are 53%, 28% and 15%, respectively. Their contributions to the total GSL are 42%, 22% and 12%, respectively. The minor ingredients, GNL, RAA and RAE amount to 0.08 µmol/ g DM, 0.03 µmol/ g DM and 0.18 µmol/ g DM, respectively. Together, they represent 4% of aliphatic GSL and 3% of total GSL (Table 7, and Figures 6a, b, and 7a, b).
The indolic GSL concentration was 1.8 µmol/ g DM, which accounts for 20% of the total GSL (Figure 6a and Table 8). Four components were detected: GBC, NAS, 4OH and 4ME. The concentrations of these were 1 µmol/ g DM, 0.51 µmol/ g DM, 0.17 µmol/ g DM and 0.14 µmol/ g DM, respectively. These components share 55%, 28%, 9% and 8%, respectively of the total indolic GSL. Their contributions to the total GSL are 10%, 5%, 1.6% and 1.4%, respectively (Figures 6a, b and 8a, b, and Table 7).
The aromatic GSL group is represented by NEO with 0.17 µmol/ g DM, with a share of 2% of total GSL (Figures 6a, b and 9, and Tables 7 and 8).
Samourai GSL content under control conditions
Under control conditions, Samourai showed a total GSL content of as high as 6.4 mmol/ g DM. The aliphatic GSL were the predominant class, with 4.25 µmol/ g DM, which accounts for 66% of the total GSL (Table 8). The major components are PRO, GBN and GNA. The absolute values of these components were 1.9 µmol/ g DM, 1.4 µmol/ g DM and 0.67 µmol/ g DM, respectively. The shares of these components in the aliphatic GSL are 46%, 34% and 16%, respectively. Their contributions to the total GSL are 30%, 22% and 10%, respectively (Figure 6a, b, Figure 7a, b). The remaining components of the aliphatic class are GNL, RAA and RAE. Their concentrations are rather low in comparison to the major components. All of them together represent 3%
of the aliphatic GSL and 2.8% of the total GSL content (Figures 6a, b and 7a, b, and Table 7).
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Figure IV-6: (a) Total glucosinolate content µmol/ g DM of each component in parents and the DH population under control and salt, (b) Percentage of each component relative to the total GSL content in parents and the DH population under control and salt
0.00 2.00 4.00 6.00 8.00 10.00 12.00
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Absolute cocentration of total GSL components µmol/ g DM
PRO GNL RAA RAE GNA 4 OH GBN GBC NAS 4ME NEO
0% 20% 40% 60% 80% 100%
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Percentage of each component of total GSL (%)
PRO GNL RAA RAE GNA 4 OH GBN GBC NAS 4ME NEO
b) a)
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Figure IV-7: a) Absolute values of aliphatic GSL components µmol/ g DM in the parents and the DH population under control and salt, b) Percentage of each ingredient of the aliphatic GSL in the aliphatic GSL content in parents and the DH population under control and salt
0.00 2.00 4.00 6.00 8.00 10.00
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Aliphatic GSL µmol/g DM
PRO GNL RAA RAE GNA GBN
0% 20% 40% 60% 80% 100%
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Percentage of each component of aliphatic GSL (%)
PRO GNL RAA RAE GNA GBN
b)
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Figure IV-8: a) Absolute values of indolic GSL components µmol/ g DM in the parents and the DH population under control and salt, b) Percentage of each ingredient of indolic GSL in the indolic GSL content in parents and the DH population under control and salt
0.00 0.50 1.00 1.50 2.00 2.50 3.00
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Indolic GSL µmol/g DM
4 OH GBC NAS 4ME
a)
0% 20% 40% 60% 80% 100%
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Percentage %
percentage of each component in the indolic GSL
4 OH GBC NAS 4ME
b)
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Figure IV-9: Absolute values of aromatic GSL components µmol/ g DM in the parents and the DH population under control and salt
0 0.05 0.1 0.15 0.2 0.25
Mansholts Samourai DH Population Mansholts Samourai DH Population
CONTROLSALT
Aromatic GSL µmol/ g
NEO
0 10 20 30 40 50
0 2 4 6 8 10 12 14 16
Number of DH lines
Total GSL content µmol/ g DM
Control Salt
S
S
M M
Figure IV-10: Distribution of total GSL µmol/ g DM of Brassica napus DH population Mansholts x Samourai under control and salt stress
• Red and bold arrows refers to parents GSL content under salt stress
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GBC and NAS are the major components with 1.3 µmol/ g DM and 0.37 µmol/ g DM, respectively; their shares in the indolic GSL are 64% and 19%, respectively. These components share 20% and 60% of the total GSL, respectively. The minor components, 4OH and 4ME have the same concentration of 0.16 µmol/ g DM;
collectively they share 16% of the GSL and 3% of the total GSL (Figures 6a, b and 7a, b, and Tables 7 and 8).
The NEO concentration was 0.22 µmol/ g DM, which represents less than 4% of the total GSL (Figure 6a, b, Figure 9, and Table 7).
The ratios of the GSL content of Mansholts relative to Samourai are 151%, 180%, 94% and 77%, and for total GSL, aliphatic, aromatic and indolic GSL, respectively.
These findings declare that Mansholts have a high aliphatic GSL content compared to Samourai. Nevertheless, Samourai show high indolic and aromatic GSL. Regarding the individual components, Mansholts dominated Samourai in all GSL component categories, except RAA, 4OH and GBC (Figure 6a, b, and Table 7).