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1.
J Plant Physiol ; 165(8): 845-57, 2008 May 26.
Article in English | MEDLINE | ID: mdl-17920158

ABSTRACT

In this study, morphological, ultrastructural and physiological modifications of faba bean (Vicia faba cv Giza 461) leaves in response to bean yellow mosaic virus (BYMV) infection and salicylic acid (SA) treatments were examined. Under BYMV stress, leaves showed symptoms including severe mosaic, mottling, crinkling, size reduction and deformations. Three weeks after virus inoculation, photosynthetic rate, pigment contents and transpiration rate were significantly reduced in response to BYMV infection. Ultrastructural investigations of BYMV-infected leaves demonstrated that most chloroplasts with increased stromal area became spherical in shape and some lost their envelopes, either partially or totally. The internal structures of chloroplast, grana and thylakoids were dilated. Two kinds of inclusions were detected in BYMV-infected leaves: straight or slightly curved bands sometimes coiled or looped at the end, and electron opaque crystals with varied shapes. BYMV-infected cells showed lower chloroplast number in comparison to the control. Spraying of SA on faba bean leaves helped to reduce or prevent the harmful effects produced after virus infection. Application of 100 microM SA three days before inoculation restored the metabolism of infected leaves to the levels of healthy controls. SA treatment improved plant health by increasing the photosynthesis rates, pigment contents and levels of other parameters studied similar to control values. Moreover, SA treatment increased plant resistance against BYMV. This was observed through induction of chloroplast number, reduction in percentage of infected plants, decrease in disease severity and virus concentration of plants treated with SA prior to BYMV inoculation. Cells of SA-treated samples showed well-developed chloroplasts with many starch grains and well-organized cell organelles. The present results provide an overview of the negative effects on faba bean leaves due to BYMV infection from physiological and subcellular perspectives. Also, a role of SA involved in induction of resistance against BYMV infection in bean plants is discussed.


Subject(s)
Plant Diseases/virology , Plant Leaves/virology , Plant Viruses/drug effects , Protective Agents/pharmacology , Salicylic Acid/pharmacology , Vicia faba/drug effects , Vicia faba/virology , Carbon Dioxide/metabolism , Cell Nucleus/drug effects , Cell Nucleus/ultrastructure , Chloroplasts/drug effects , Chloroplasts/ultrastructure , Chloroplasts/virology , Inclusion Bodies, Viral/drug effects , Inclusion Bodies, Viral/ultrastructure , Photosynthesis/drug effects , Pigments, Biological/metabolism , Plant Leaves/cytology , Plant Leaves/growth & development , Plant Leaves/ultrastructure , Vicia faba/anatomy & histology , Vicia faba/ultrastructure , Virion/drug effects , Virion/ultrastructure
2.
Plant Physiol Biochem ; 45(6-7): 480-9, 2007.
Article in English | MEDLINE | ID: mdl-17466528

ABSTRACT

The changes of some physiological and biochemical parameters in pumpkin (Cucurbita pepo cv Eskandarani) leaves associated with zucchini yellow mosaic virus (ZYMV) infection and the effect of exogenous application of salicylic acid (SA) were studied in this paper. In comparison to the untreated leaves, ZYMV infected leaves showed many symptoms, including severe mosaic, size reduction, stunting and deformation. Results from analysis of physiological parameters indicated that viral infection and SA treatments affected metabolism. Viral infection decreased pigment, protein and carbohydrate levels. But with all SA treatments, the protein and carbohydrate contents are noticeably increased. Moreover, the other biochemical parameters showed variable alterations. The peroxidase (POX, EC 1.11.1.7) activity and proline contents were induced by both viral infection and SA treatments. In addition, protein patterns represent some newly synthesized polypeptides which reflect formation of pathogenesis related proteins in all treatments. SA treatment increases the plant resistance against ZYMV. This can be noticed through reduction of percentage of the infected plants, decrease in disease severity and virus concentration of the plants treated with SA then inoculated with virus. All results show significant changes in metabolism affected by either viral infection or SA treatments and also indicate that exogenous SA plays an important role in induction of defense mechanism against ZYMV infection.


Subject(s)
Cucurbita/virology , Mosaic Viruses/pathogenicity , Plant Leaves/virology , Salicylic Acid/pharmacology , Carbohydrates/analysis , Cucurbita/drug effects , Plant Diseases/virology , Plant Leaves/drug effects , Plant Leaves/metabolism , Plant Proteins/metabolism , Proline/metabolism
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