SO2 STRESS: ITS EFFECT ON PLANTS, PLANT DEFENCE RESPONSES AND STRATEGIES FOR DEVELOPING ENDURING RESISTANCE

Abstract: In the present scenario of rising SO2 in the atmosphere, the negative impact of this obnoxious gas on the plants is among major concerns in the field of agriculture and crop protection. From the scientific research conducted so far, it has been established that the main toxic effect of SO2 on plant system is exerted by the resulting oxidative stress and generation of sulphite ions. Prominent adverse effect is observed on the overall plant growth and health, Photosynthetic efficiency and produce turn over. On the other hand, plant defence mechanism tries to counter the stress either by inhibiting the entry of the gas by or by detoxifying the excess sulphur and scavenging the resulted reactive oxygen species. Enzymes like superoxide dismutase, peroxidase, polyphenol oxidase, play a key role in the detoxifying process and a considerable amount of toxic sulphur is detoxified by forming S-containing sulphur compounds. This phenomenon is being utilized for the development of SO2 resistant plant lines by over-expression of Cysteine synthase like genes. This review presents literature study of SO2 induced effects on plants as well as plant resistance against it and approaches toward developing enduring resistance in plants.

Keywords: Sulphur dioxide stress, Sulphite toxicity, Abiotic stress, Oxidative stress response, Plant defence.