Implication of rhizosphere acidification in nutrient uptake by plants: Cases of potassium (K), phosphorus (P), and iron (Fe)

Abstract

The rhizosphere represents the interface between soil and roots. In this zone, many interactions between plant roots and the soil solution occur and result in important modifications of the physicochemical properties in this area. Plants require large amounts of nutrients to assure maximum growth and development. The absorption of excess nutrients by roots leads to many changes in the rhizosphere such as the acidification phenomenon which is known to be a continuous process in many soils through the world. It is due to the extrusion of protons at the root plasma membrane in favor of cation influx, a principal way used by plants to remove nutrients from the soil solution. Rhizosphere acidification plays a crucial role in nutrient acquisition by plants and is attributed to the activity of H+ATPase pumps located at the plasmalemma. The implication of proton release in nutrient acquisition by plants was proved under low nutrient availability. Thus, an increase of the H+ATPase activity was noted under a deficiency in many essential nutrients. Due to new advances in molecular biology, the role of H+ATPases in nutrient uptake by plants is more elucidated and many genes encoding these pumps are identified. In the present chapter, we summarize information gained on the role of rhizosphere acidification in the uptake of two essential macronutrients and a key micronutrient, respectively, potassium (K), phosphorus (P), and iron (Fe), especially under deficiency conditions and we describe the recent findings related to H+ATPases that drive the acidification process.