Role of reactive sulfur species in the oxidative metabolism in plants

Sulfur is a member of chalcogen group and play a significant role in many essential processes such as electron transport, cellular structure and regulation of plant metabolism. It is closely linked with the production of photosynthetic oxygen, resistance against environmental stresses, and secondary cellular metabolism. Sulfur‐containing defense compounds that are vital for plant survival during oxidative stress include thiols, hydrogen sulfide, phytochelatins, glutathione, S‐rich proteins, and numerous secondary metabolites. Similar to Oxygen and nitrogen, sulfur also produce reactive species in response to oxidative stress in plant. Most important of those species are thiol compounds. In oxidative metabolism of plants, reactive sulfur species (RSS) play significant role acting as first line of defense against the damaging ROS. These species are highly reactive and participates in reactions that encompass the transmission of one‐ and two electrons and hydride. These sulfur species are also the part of many physiological exchange reactions associated with variation in the formal oxidation state. In this chapter, different forms of RSS that have essential role in oxidative metabolism of plants, their source and mechanism of generation and role in protecting the plant against cellular damages under diverse oxidative conditions are summarized.