Medical/biological study (experimental study)

Weak microwave can alleviate water deficit induced by osmotic stress in wheat seedlings med./bio.

By: Chen YP, Jia JF, Han XL

Published in: Planta 2009; 229 (2): 291-298

Aim of study (acc. to author)

To study the effect of microwave pretreatment on wheat seeds on the resistance of seedlings to osmotic stress and to evaluate the potential biological effects of low-level microwaves on oxidative damage (induced by osmotic stress).

Background/further details

High activities of antioxidant enzymes and high contents of non-enzymatic constituents (e.g. antioxidants) are important for plants to tolerate environmental stresses.
Six different doses of microwave exposure (0, 5, 10, 15, 20, 25 s) were tested to select the best dose for a following protective experiment (resistence to osmotic stress). In the protective experiment, wheat seeds were randomly divided into four experimental conditions: 1) control group, 2) microwave exposure, 3) osmotic stress: polyethylene glycol 600, 4) microwave exposure (10 s) + osmotic stress (polyethylene glycol 600). At least three replications were performed.

Endpoint

osmotic stress (oxidative damage) in wheat seedlings and protection by microwave pretreatment

Exposure

- microwaves

Exposure	Parameters
Exposure 1: unspecified Exposure duration: 5, 10, 15, 20 or 25 s	magnetic field intensity: 10 mH - 55 mH; measured 6 h after exposure

General information

seeds were divided into four groups: i) control - no treatment ii) exposure to microwaves for 10 s iii) osmotic stress iv) exposure to microwaves for 10 s + osmotic stress

Exposure 1

Main characteristics

Frequency	unspecified
Type	electromagnetic field
Exposure duration	5, 10, 15, 20 or 25 s

Exposure setup

Exposure source	microwave oven
Setup	seeds placed in the center of the microwave oven

Parameters

Measurand	Value	Type	Method	Mass	Remarks
cf. remarks	-	-	-	-	magnetic field intensity: 10 mH - 55 mH; measured 6 h after exposure

Exposed system:

plant
wheat (Triticum aestivum L.)

Methods Endpoint/measurement parameters/methodology

cell function: oxidative stress: enzymatic defense (superoxide dismutase, catalase, peroxidase, nitric oxide synthase) and non-enzymatic (nitric oxide, glutathione, ascorbic acid, malondialdehyde) defense mechanims (different enzyme and protein assays, spectrophotometry)
thermoregulation: temperature of seeds (to select the best dose in microwave pretreatment; infrared thermometer)
biomass determination and seed height; α-amylase enzyme activity and biophoton emission intensity of seeds (to select the best dose for microwave pretreatment)

Investigated system:

isolated bio./chem. substance
(dried) seed samples and seed sample homogenates and supernatants

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The seed temperature increased progressively with microwave pretreatment dose compared to the control group. Each microwave pretreatment resulted in an increased α-amylase enzyme activity and biophoton emission intensity with a peak value at microwave pretreatment of 10 s.
In the seedlings with microwave exposure and osmotic stress (group 4), the concentration of malondialdehyde decreased, while the enzyme activities of nitric oxide synthase, catalase, peroxidase, superoxide dismutase and concentration of nitric oxide, ascorbic acid and glutathione increased.
The results suggest that a suitable dose of microwave exposure can enhance the capability of plants to eliminate free radicals and thus may alleviate water deficit induced by osmotic stress in wheat seedlings.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

National Natural Science Foundation (NSFC), China
West China Star of CAS

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