Sodicity-induced antioxidative system in roots of salt-tolerant and salt-sensitive cultivars of Indian mustard (Brassica juncea L.)

Abstract

A differential response of sodicity was observed on enzymatic and non-enzymatic components of antioxidant
system in roots of salt-sensitive RH 8113 and salt-tolerant CS 52 varieties of Indian mustard (Brassica
juncea L.). The antioxidative enzymes viz. superoxide dismutase (SOD), glutathione reductase (GR),
peroxidase (POX), and ascorbate peroxidase (APX) showed higher basal activities in roots of salt-tolerant
CS 52 cultivar as compared to salt-sensitive RH 8113. Imposition of sodicity stress (15-45 ESP) had no effect
on SOD and APX activity in roots of CS 52, but it resulted in reduction in activity in salt-sensitive RH 8113.
In both varieties, the POX activity decreased progressively with increase in stress level , but the level of
decrease was more in RH 8113 as compared to that in salt-tolerant CS 52. Contrarily, GR activity increased
in tolerant cultivar CS 52, but showed a continuous reduction with increment in sodic stress in the sensitive cv.
RH 8113. The amount of ascorbic acid, reduced glutathione, and ratio of reduced (GSH)/ oxidized glutathione
(GSSG) were higher in tolerant than in sensitive ciltivar under sodic conditions. It is inferred that roots of
tolerant cv. CS 52 tend to attain greater capacity to perform reaction of antioxidative pathway under sodic
conditions to combat sodicity-induced oxidative stress.