Silva, A. L. L et al. 3

J. Biotec. Biodivers. v. 1, N.1: pp. 1-5, Nov. 2010

Figure 1- Survival of cotyledons of Eucalyptus saligna cultivated at different levels of kanamycin after 28, 56 and 84 days of in vitro culture.

These results have suggested that lower levels of kanamycin must be used as selection agent for genetic transformation of cotyledons of E. saligna .

These levels are below of the kanamycin level used in a genetic transformation protocol established to E. saligna , which is 50 mg.L ; however this protocol was developed for leaf explants (Dibax, 2007).

Tolerance to kanamycin in shoot tip

The presence of kanamycin on media culture have affected rate proliferation, each 28 days we have observed decreases in shoot number of shoot tip, these data followed a negative linear effect (Figure 2).

y = -0.14x + 2.72 R = 0.93

0

0,5

1

1,5

2

2,5

3

50 75 100 125 150

Kanamycin (mg.L )

Shoot number

A

y = -0.31x + 4.28

R = 0.89

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

50 75 100

125 150

Kanamycin (mg.L )

Shoot number

B

y = -0.303x + 2.44

R = 0.94

0

0,5

1

1,5

2

2,5

50 75 100

125 150

Kanamycin (mg.L )

Shoot number

C

y = -0.195x + 1.841

R = 0.77

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

50 75 100 125 150

Kanamycin (mg.L )

Shoot number

D

Figure 2- Effect of kanamycin in shoot number of shoot tip of Eucalyptus saligna after (A) 28, (B) 56, (C) 84 and (D) 112 days of in vitro culture.

In the first and second month, shoot tip have multiplicated in presence of kanamycin, in all levels (50-150 mg.L ), however at the third month, shoots begin to die (Figure 2C). At the fourth month, shoot tip had just one shoot cultivated on levels of 100 to 150 mg.L kanamycin, (Figure 2D).

Survival percentage of shoot tip followed a negative quadratic effect. Shoot tip begin to die at the third month, survival rate at 50 mg.L stayed 100%, while higher levels promoted explants dead (Figure 3A).