Abstract The aim of the study was to relate the effects of
deficiency and excess of Mn with the generation of reactive
oxygen species (ROS) and altered cellular redox environment
in mulberry (Morus alba L.) cv. Kanva-2 plants. Mn
deficiency symptom appeared as mild interveinal chlorosis
in middle leaves. Mn-excess did not produce any specific
symptom. Leaf water potential (W) was increased in Mndeficient
and Mn-excess mulberry plants. Mn-deficient
leaves contained less Mn, less chloroplastic pigments and
high tissue Fe, Zn and Cu concentrations. Starch content
was increased with increasing Mn supply. While reducing
sugar content increased in Mn-deficient and Mn-excess
plants as well, non-reducing sugars remained unaffected in
Mn-deficient plants and decreased in Mn-excess plants.
Moreover, study of antioxidative responses, oxidative
stress (H2O2 and lipid peroxidation) and cellular redox
environment [dehydroascorbate (DHA)/ascorbic acid
(AsA) ratio] in Mn-stressed mulberry plants was also
undertaken. Both hydrogen peroxide and lipid peroxidation
were enhanced in the leaves of Mn-deficient plants.
Increased H2O2 concentration in Mn-excess leaves did not
induce oxidative damage as indicated by no change in lipid
peroxidation. The ratio of the redox couple (DHA/AsA)
was increased both in Mn-deficient or Mn-excess plants.