Figure 3个  Table 4
    • Days after infection Relative infectivity (%), TMV + chitosan Inhibitory effect (%) Relative infectivity (%), TMV after treatment with chitosan for 24 h Inhibitory ffect (%)
      3 37 ± 4.1*** 63 59 ± 6.2*** 41
      5 59 ± 6.0*** 41 74 ± 7.6** 26
      7 74 ± 7.8** 26 82 ± 8.8* 18
      TMV concentration, 2 μg /mL; chitosan concentration, 1 mg /mL. The relative infectivity is the number of local lesions per leaf half of N. tabacum L. cv. Xanthi-nc, expressed as a percentage of the untreated control. Each value is the average percentage obtained on 50 leaf halves of N. tabacum L. cv. Xanthi-nc (± standard error). The differences are statistically significant relative to controls at P* < 0.05, P** < 0.01 and P*** < 0.001.

      Table 1.  The effect of chitosan on infectivity in N. tabacum L. cv. Samsun leaves infected with TMV

    • Days after infection Content of viral coat protein (ng/mm2) Inhibitory effect
      (%)
      Content of viral coat protein (ng/mm2) Inhibitory effect
      (%)
      TMV + chitosan Control TMV after treatment with chitosan for 24 h Control
      3 1.5 ± 0.17*** 4.4 ± 0.5 66 2.1 ± 0.23*** 4.1 ± 0.42 49
      5 6.1 ± 0.7** 11.5 ± 1.3 47 9.3 ± 0.94* 13.5 ± 1.45 31
      7 18 ± 1.8* 25 ± 2.6 28 18.5 ± 1.9 22.3 ± 2.3 17
      The viral coat protein content in test and control leaves was measured by ELISA and calculated for leaf disk areas of 1 mm2. Each value is the average of 10 replicates (± standard error). The differences are statistically significant relative to controls at P* < 0.05, P** < 0.01 and P*** < 0.001.

      Table 2.  The effect of chitosan on viral coat protein content in N. tabacum L. cv. Samsun leaves infected with TMV

    • Days after infection Hydrolases The activities of hydrolase (OD)
      TMV + chitosan TMV
      3 Proteases 0.53 ± 0.05 0.38 ± 0.04
      RNases 0.47 ± 0.05 0.32 ± 0.04
      5 Proteases 0.50 ± 0.05 0.35 ± 0.04
      RNases 0.38 ± 0.04 0.26 ± 0.03
      7 Proteases 0.35 ± 0.04 0.23 ± 0.03
      RNases 0.31 ± 0.03 0.21 ± 0.02
      The activities of hydrolases were determined in 50 disks (4 mm in diameter) cut from leaf halves and expressed in terms of optical density. Each value is the average of 5 replicates (± standard error). The differences are statistically significant relative to controls at P < 0.05.

      Table 3.  The activity of hydrolases in leaves N. tabacum L. cv. Samsun inoculated with TMV mixed with chitosan and inoculated with TMV alone

    • Diameter of TMV particles, nm Number of TMV particles
      TMV + chitosan TMV
      12 68 ± 7.0** 11 ± 2.5
      14 104 ± 12** 22 ± 4.0
      16 31 ± 4.0* 65 ± 7.0
      18 105 ± 12** 251 ± 25
      20 39 ± 5.0** 10 ± 1.5
      22 24 ± 3.0 18 ± 2.0
      24 29 ± 3.5 23 ± 3.0
      The diameters of TMV virions were measured for 20 randomly selected viewing fields at a total magnification of x150000. Experiments were repeated three times. In each experiment, the diameters of 400 viral particles from the test sample and 400 particles from the control sample were measured. Each value is the average of three experiments (± standard error). The differences are statistically significant relative to controls at P* < 0.05 and P** < 0.01.

      Table 4.  Diameter distribution of PTA-stained TMV particles in sap from N. tabacum L. cv. Samsun leaves 3 days after inoculation with TMV mixed with chitosan and with TMV alone