Aromatic glucosinolate

The content of gluconasturtiin in leaves varied essentially during the plant growth. For H leaves it increased from 0.1 mg plant^-1 on 10^th day to 0.2 on 20^th, then disappeared to the end of the experiment. Also in AD and AS leaves gluconasturtiin was extremely reduced until the end of plant growth (Table 4.28, Attachment, Tables 4.28a and 4.28b).

Application of SA markedly increased the content of gluconasturtiin in leaves, especially during the first half of the experiment. On 10^th day the content of glucosinolate in HSA0

leaves became 3-folds higher then for H (0.3 mg plant^-1), in 5 days 5-folds higher (0.5 mg plant^-1), on 20^th day it decreased, but to the end of the experiment gradually increased until 0.4 mg plant^-1. The same essential increment until 15^th day was also measured for ADSA0 (0.4 mg plant^-1, while for AD 0.1 mg plant^-1), the next 5 days decrease, and then gradually increased until the end of experiment. Probably the firs peak on 15^th day is the response of plant on stress, simulated by SA application, and the second, slow increment is forming of plant

Results and discussions

resistance against this factor. This supposes could be supported by the observation of Kiddle et al. (1994) that the response to elicitor influence is the only one event.

The increase in aromatic glucosinolates after SA and MJ application might be explained by SA (Wielanek and Urbanek, 1999)and MJ (Mikkelsen et al., 2003) induction of CYP79A2 that converts phenylalanine to aromatic aldoxime.

Table 4.28. Elicitor influence on aromatic glucosinolate content in plants and exudates of turnip from hydroponic (mg plant^-1)

Date Treatment Leaves Secondary

roots Primary roots Exudates H 0.1^a ± 0.1 0.2^a ± 0.0 0.1^a ± 0.0 HSA0 0.3^b ± 0.0 0.5^b ± 0.1 0.3^b ± 0.0 10 days

HMJ0 0.1^a ± 0.1 0.3^ab ± 0.1 0.5^c ± 0.0 H 0.1^a ± 0.1 0.3^a ± 0.1 1.6^b ± 0.1 0.1^a ± 0.0 HSA0 0.5^b ± 0.1 0.6^b ± 0.1 1.5^b ± 0.1 0.3^b ± 0.1 15 days

HMJ0 0.1^a ± 0.1 0.5^b ± 0.1 0.8^a ± 0.0 0.3^b ± 0.1 H 0.2^a ± 0.2 0.9^a ± 0.2 1.9^b ± 0.1 0.2^a ± 0.1 HSA0 0.2^a ± 0.1 1.6^b ± 0.1 2.0^b ± 0.1 0.4^ab ± 0.1 20 days

HMJ0 0.2^a ± 0.2 1.2^ab ± 0.2 0.7^a ± 0.1 0.5^b ± 0.1 H 0.1^a± 0.1 1.3^a± 0.2 2.2^ab± 0.4 0.3^ab ± 0.1 HSA0 0.3^a ± 0.2 2.6^c ± 0.3 3.5^b ± 0.2 0.4^b ± 0.1 25 days

HMJ0 0.3^a ± 0.1 1.9^b ± 0.1 2.3^a ± 0.3 0.3^a ± 0.0 H ND 1.2^a ± 0.4 0.7^a ± 0.2 0.4^a ± 0.1 HSA0 0.4^a ± 0.2 2.3^b ± 0.4 3.4^b ± 0.3 0.4^a ± 0.1 30 days

HMJ0 0.6^a ± 0.2 2.8^b ± 0.3 3.8^b ± 0.4 0.4^a ± 0.1

H 1.2^a ± 0.3*

HSA0 1.8^ab ± 0.4*

Total

HMJ0 2.1^a ± 0.2*

H - hydroponic, two times concentrated Hoagland solution + two times increased sulfur; HSA0 - hydroponic, two times concentrated Hoagland solution + two times increased sulfur + salicylic acid applied on the beginning;

HMJ0 - hydroponic, two times concentrated Hoagland solution + two times increased sulfur + methyl jasmonate applied on the beginning. The differences are compared for each treatment. Values followed by the same letter are not significantly different. ND- not determined. *Sum of glucosinolates exuded during 30 days

It is possible to conclude that SA prevented the disappearance of metabolites as in leaves of plants from hydroponic. Treatment with MJ oppositely did not change the gluconasturtiin content in leaves in the first half of the experiment as compared to untreated variants. But since 25^th day the content of glucosinolate for HMJ0 leaves became 0.3 mg plant^-1 (3-folds more as for H) and for ADMJ0 0.4 mg plant^-1 (4-folds more as for AD); on 30^th day it reached 0.6 and 0.3 mg plant^-1, respectively (Table 4.28, Attachment, Tables 4.28a and 4.28b) . For H and AS the content of gluconasturtiin in secondary roots of turnip increased gradually to 1.2 and 1.5 mg plant^-1 on 30^th day. For AD it increased until 1.3 mg plant^-1 on 25^th day, and then decreased to 0.8 mg plant^-1 on 30^th day.

Application of both of elicitors increased the content of gluconasturtiin in secondary roots.

Already 10 days after the treatment, the differences in gluconasturiin content were measured.

For HSA0 it reached 0.5 and for HMJ0 0.3 mg plant^-1, while for H 0.1 mg plant^-1. The fastest

enhancement of gluconasturiin content in secondary roots of SA treated plants was observed between 15^th-20^th days: for HSA0 by 1.0 mg plant^-1 (from 0.6 until 1.6), for ADSA0 by 1.1, and for ASSA0 by 0.5 mg plant^-1. On 30^th day the HSA0 secondary roots 2-folds more gluconasturtiin then H, ADSA0 2.7-folds more then AD, and ASSA0 1.7-fold more then AS.

For MJ treatment the content of gluconasturtiin in secondary roots increased progressively with plant growth. At the end of experiment HMJ0 secondary roots had 2.8 mg plant^-1 of gluconasturtiin (2.3-folds more then H) and ADSA0 1.9 mg plant^-1 (2.4-folds more then AD).

The content of gluconasturtiin in H primary roots until 25^th day gradually increased until 2.2 mg plant^-1, but then decreased to 0.7 mg plant^-1. In aeroponics this decrease was not measured. This could be explained by the fact that the plants from hydroponic developed faster as these in aeroponics (see 4.2.3).

Treatment with SA increased the content of gluconasturtiin in primary roots right after the application. This effect kept until the end of experiment, when the HSA0 primary roots accumulated 3.4 mg plant^-1 (4.8-folds more then H). Until 20^th day MJ treatment caused the decrease of gluconasturtiin content in primary roots: for HMJ0 on 15^th day it achieved 0.8 and on 20^th day 0.7 mg plant^-1 (respectively 0.7 and 1.2.mg plant^-1 lower as for H), and on 30^th day it reached 3.8 mg plant^-1 (0.4 mg plant^-1 higher as in H). The decrease of glucosinolate content in primary roots under MJ treatment could be explained by the suppression of plant growth and development under the influence of elicitor (see 4.2.3).

CYP79B2 converts tryptophan to aromatic aldoxime and has the highest expression level in leaves, but not in roots (Glombitza et al., 2004). Increases of aromatic glucosinolate in leaves for MJ treatment as compared to the non-treated variant and the absence of an effect after SA application could be explained by the influence that MJ on CYP79B2 in contrast to SA (Wasternack and Parthier, 1997; Mikkelsen et al., 2000).

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

10 15 20 25 30

days

Glucosinolate, mg plant-1

H HSA0 HMJ0

H - hydroponic, two times concentrated Hoagland solution + two times increased sulfur; HSA0 - two times concentrated Hoagland solution + two times increased sulfur + salicylic acid; HMJ0 - two times concentrated Hoagland solution + two times increased sulfur + methyl jasmonate applied on the beginning

The content of gluconasturtiin gradually increased in exudates of all non-elicited treatments:

from 0.1 mg plant^-1 for H, AD, and AS on 10^th day to 0.4, 0.5, and 0.3 mg plant^-1 on 30^th day, respectively (Figure 4.11).

SA and MJ increased the content of aromatic glucosinolate right after the application, and the maximal effect was observed on 20^th day in hydroponics (0.5 mg plant^-1 of gluconasturtiin for HMJ0

and 0.4 mg plant^-1 for HSA0), and on 15^th day in aeroponics

(0.5 mg plant^-1 of

gluconasturtiin for ADMJ0, and 0.5 and 0.6 mg plant^-1 for ADSA0 and ASSA0).

Results and discussions

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

10 15 20 25 30

days

Glucosinolate, mg plant-1

AD ADSA0 ADMJ0

AD – aeroponic with defensor, two times concentrated Hoagland solution + two times increased sulfur; ADSA0 - two times concentrated Hoagland solution + two times increased sulfur + salicylic acid; ADMJ0 - two times concentrated Hoagland solution + two times increased sulfur + methyl jasmonate applied on the beginning

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7

10 15 20 25 30

days

Glucosinolate, mg plant-1

AS ASSA0

AS – aeroponic with sprayer, two times concentrated Hoagland solution + two times increased sulfur; ADSA0 - two times concentrated Hoagland solution + two times increased sulfur + salicylic acid

Figure 4.11. Elicitor influence on kinetic of aromatic glucosinolates in exudates of turnip

However, the increment of gluconasturtiin content under the elicitor influence was diminished with time and at the end of experiment it became the same (for HSA0

and HMJ0) or lower (for ADSA0, ASSA0, and ADMJ0) value as for untreated variants.

In general, SA increased the amount of exuded gluconasturtiin for HSA0 to 1.5-fold more then for H (1.8 mg plant^-1), for ADSA0 as well as for ASSA01.4-fold more then for AD and AS (3.7 and 2.5 mg plant^-1, respectively) (Table 4.28, Attachment, Table 4.28a and 4.28b).

MJ application led to enhance the gluconasturtiin content for HMJ0 exudates to 2.1 mg plant^-1 (1.8-fold more then for H) and for ADSA0 to 4.2 mg plant^-1 (1.6-fold more then for AD (Table 4.28, Attachment, Table 4.28a and 4.28b).

Wielanek and Urbanek (1999) also reported about increase the yield of aromatic glucosinolates by about 40-70% under the influence of MJ. In Brassica napus

biosynthesis of gluconasturtiin is specifically

induced by salicylic acid (SA), a signaling compound involved in many plant physiological processes (Kiddle et al., 1994).

Gluconasturtiin showed the greatest increase in concentration, with only minor increases in other glucosinolates in developing leaves (Kiddle et al., 1994).

However, Doughty et al. (1995) found, that in Brassica napus MJ induced only indole glucosinolate synthesis, whereas aliphatic and aromatic glucosinolates were unaffected. The induction of gluconasturtiin content in turnip and its exudates may be related to the fact that

this is the only aromatic glucosinolate produced by this plant, similar as it was explained by Wielanek and Urbanek (1999) for Tropaeolus majus and glucotropaeolin.