Changes in Salicylic Acid and Antioxidants during Induced Thermotolerance in Mustard Seedlings

Abstract

Heat-acclimation or salicylic acid (SA) treatments were previously shown to induce thermotolerance in mustard (Sinapis alba L.) seedlings from 1.5 to 4 h after treatment. In the present study we investigated changes in endogenous SA and antioxidants in relation to induced thermotolerance. Thirty minutes into a 1-h heatacclimation treatment glucosylated SA had increased 5.5-fold and then declined during the next 6 h. Increases in free SA were smaller (2-fold) but significant. Changes in antioxidants showed the following similarities after either heat-acclimation or SA treatment. The reduced-to-oxidized ascorbate ratio was 5-fold lower than the controls 1 h after treatment but recovered by 2 h. The glutathione pool became slightly more oxidized from 2 h after treatment. Glutathione reductase activity was more than 50% higher during the first 2 h. Activities of dehydroascorbate reductase and monodehydroascorbate reductase decreased by at least 25% during the first 2 h but were 20% to 60% higher than the control levels after 3 to 6 h. One hour after heat acclimation ascorbate peroxidase activity was increased by 30%. Young leaves appeared to be better protected by antioxidant enzymes following heat acclimation than the cotyledons or stem. Changes in endogenous SA and antioxidants may be involved in heat acclimation.

Growth of Indian mustard (Brassica juncea L.) in response to salicylic acid under high-temperature stress

“…For example, generation and reaction of activated oxygen species (AOS), which causes the autocatalytic peroxidation of membrane lipids and pigments subsequently leads to membrane permeability and modification of its functions (Xu et al, 2006). Recent studies show that some signaling molecules may increase the antioxidant capacity of cells (Gong et al, 1997;Dat et al, 1998). Extreme temperatures led to accumulation of certain organic compounds termed osmolyte, including sugars, polyols, and proline.…”

Effect of Salicylic Acid and Calcium Nitrate Spraying on Qualitative Properties and Storability of Fresh Jujube Fruit (Ziziphus jujube Mill.)

“…4A. Salicylic acid as an antioxidant activates ascorbate peroxidase, which, in turns, increases antioxidant ability and ascorbic acid amount in fruits (Dat et al, 1998;Wang et al, 2006). In addition, it has been shown that salicylic acid affects the biosynthesis and action of ethylene (Srivastava and Dwivedi, 2000), prevents vitamin C from being destructed (Wisniewska and Chelcowski, 1999) and acts as an anti-stress power (Elwana and El-Hamahmy, 2009).…”

Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance

“…Efficient elimination of H 2 O 2 was possible due to the elevated GSH level in heat stressed mustard seedlings, which was facilitated by improved GR activity (Dat et al 1998). Higher GSH levels at the reproductive stage in apple plants enhanced their capacity for HT acclimation.…”