Induction of pathogenesis-related (PR)‎ proteins as a plant defense mechanism for controlling the cotton whitefly Bemisia tabaci

Abstract EN

The activities of four pathogenesis-related (PR) proteins (Beta-1, 3-glucanase, chitinase, polyphenol oxidase and
peroxidase) were determined in both Bemisia tabaci infested and non-infested tomato plants.

Beta-1, 3-glucanase activity
in non-infested and 24, 48, 72 and 96 h infested tomato plants with B.

tabaci, were spectrophotometrically determined.

The results show that the activity of the enzyme was significantly increased in comparison to control.

The activity of β-
1, 3-glucanases was slightly pronounced one day after infestation and reached maximum level after three days (3.3-folds
than control).

The accumulation of chitinase started to increase with time one day after infestation (1.2 folds over control).

Chitinase specific activity increased significantly after 48 h of whitefly feeding and continued in elevation with time until
it reached the maximum in the fourth day of feeding.

In all treatments, polyphenol oxidase activity after 24, 48, 72 or 96 h
of whitefly infestation increased more than control.

The activity increased substantially after 24 h of feeding of whitefly
(4.3 folds than control).

The maximum rate of activity of peroxidase was exhibited after 48 h exposure to whitefly that it
had recorded 1.8 folds greater than 0-time and followed by 24 h whitefly-infested plants with 1.6-folds increase in
peroxidase activity compared to control then 72 h and 96 h after infestation (1.35 and 1.27 folds greater than control
respectively).

The PR proteins play an important defensive role against whiteflies.

Pseudomonas chlororaphis (nonpathogenic
bacteria) reduced the mean numbers of whitefly adults/cm2 by about 36.5% .

These results provide clear
evidence that tomato plants resistance is based on a variety of defense systems against several pests.

The treatment of
tomato plants with Pseudomonas spp.

caused rapid trigger systemic defenses against herbivores and pathogens.