Tree Physiology Advance Access published online on November 20, 2009
Tree Physiology, doi:10.1093/treephys/tpp093
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Morphology and oxidative physiology of boron-deficient mulberry plants
1 Department of Botany, University of Lucknow, Lucknow-226007, India
2 Present address: Laboratory of Plant Nutrition, Faculty of Horticulture, Chiba University, 648, Matsudo, 271-8510, Chiba, Japan
3 Corresponding author (sharmapn{at}sify.com)
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Abstract |
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The aim of the study was to induce B deficiency symptoms and to relate the generation of reactive oxygen species (ROS) and altered cellular redox environment with the effects of B deficiency in mulberry (Morus alba L.) cv. Kanva-2 plants. Study was undertaken on antioxidant responses, malondialdehyde (MDA) content as an indicator of oxidative damage and ratio of dehydroascorbate (DHA) to ascorbic acid (AsA) as an index of cellular redox environment in B-deficient (0.0 µM) and B-supraoptimal (33 µM) mulberry plants. B deficiency symptoms appeared as upward cupping of the young emerging leaves. Later on, B-deficient plants developed lenticels like cracks on major vein, petiole and stem. B-deficient leaves had higher water potential (
) and relative water content (RWC), contained a lower concentration of B, less chloroplastic pigments and high tissue Fe, Mn and Zn concentrations compared to the controls. Hydrogen peroxide was accumulated in leaves of B-deficient and B-supraoptimal plants. B-supraoptimal plants also showed an increased DHA/AsA ratio. The activities of superoxide dismutase (SOD, EC 1.15.1.1
[EC]
), catalase (CAT, EC 1.11.1.6
[EC]
), peroxidase (POD, EC 1.11.1.7
[EC]
) and ascorbate peroxidase (APX, EC 1.11.1.11
[EC]
) were increased in B-deficient leaves. The activities of SOD and POD were decreased in B-supraoptimal plants. The results suggest that B deficiency aggravates oxidative stress through enhanced generation of ROS in mulberry plants.
Keywords: antioxidants, B deficiency, Morus alba, oxidative stress, reactive oxygen, superoxide dismutase
Received May 11, 2009; Accepted October 2, 2009