Chapter 16 - Silicon and Selenium: Two Vital Trace Elements that Confer Abiotic Stress Tolerance to Plants

Abstract

Listen

Translate article

Plants are sessile organisms and therefore must constantly adapt their growth and architecture to an ever-changing environment. The damages in growth and development of economic plants caused due to abiotic stresses like salinity, drought, extreme temperature, flooding, toxic metals, ozone, and UV radiation are quite alarming due to shrinking agricultural land area, recurrently expanding population, and rapid climate change throughout the world. To cope with adverse growing conditions, plant scientists are searching for ways to make plants adaptive. They are trying to understand the effect of environmental stresses on plants and to modify plants’ outer growing conditions and their internal cellular environment by applying different exogenous protectants. Silicon (Si) and selenium (Se) are widely studied trace elements and their roles in plant growth and physiology are well documented. Recently, these trace elements have been found to be protective under abiotic stress conditions. Silicon is the second most abundant element after oxygen in soils and its presence in the form of silicic acid allows its uptake by plants, so by nature plants have a great scope to uptake Si in their tissues. However, those plants not supplied with sufficient natural sources of Si may benefit from its exogenous application. Selenium, an essential element for animals and humans, has also been found to be beneficial to plants. Like Si, Se also plays a protective role in conferring tolerance to certain abiotic stresses when applied at lower concentrations, while higher concentrations show phytotoxicity. However, plant species differ strongly in Se uptake and accumulation as well as their tolerance capacity. Both Si and Se were reported to play roles in conferring oxidative stress tolerance by enhancement of the antioxidant defense system in plants. Although much research has been published on the effect of Si and Se on plants under abiotic stress, clear-cut underlying physiological mechanisms of the mode by which Si could protect plants from stressful conditions are elusive. In this chapter, we attempt to summarize the uptake and accumulation pattern of Si and Se in plants. Later, we discuss the recent reports regarding the role of Si and Se in conferring abiotic stress tolerance to plants.