Aluminum stress signaling in plants

Abstract

Aluminum (Al) toxicity is a major constraint for crop production in acidic soil worldwide. When the soil pH is lower than 5, Al(3+) is released to the soil and enters into root tip cell ceases root development of plant. In acid soil with high mineral content, Al is the major cause of phytotoxicity. The target of Al toxicity is the root tip, in which Al exposure causes inhibition of cell elongation and cell division, leading to root stunting accompanied by reduced water and nutrient uptake. A variety of genes have been identified that are induced or repressed upon Al exposure. At tissue level, the distal part of the transition zone is the most sensitive to Al. At cellular and molecular level, many cell components are implicated in the Al toxicity including DNA in nucleus, numerous cytoplastic compounds, mitochondria, the plasma membrane and the cell wall. Although it is difficult to distinguish the primary targets from the secondary effects so far, understanding of the target sites of the Al toxicity is helpful for elucidating the mechanisms by which Al exerts its deleterious effects on root growth. To develop high tolerance against Al stress is the major goal of plant sciences. This review examines our current understanding of the Al signaling with the physiological, genetic and molecular approaches to improve the crop performance under the Al toxicity. New discoveries will open up new avenues of molecular/physiological inquiry that should greatly advance our understanding of Al tolerance mechanisms. Additionally, these breakthroughs will provide new molecular resources for improving the crop Al tolerance via molecular-assisted breeding and biotechnology.

Role of ROS and auxin in plant response to metal-mediated stress

“…[4][5][6][7][8][9] Recent research has revealed that metal-mediated stress seems to have a direct impact on accumulation of relative oxygen species (ROS), content of nitric oxide (NO) and hormone levels in organs and the plants can quickly adjust their growth to harsh environment by influencing the cellular redox state and hormone signaling. [10][11][12][13][14][15][16] This review provides an update on the regulation of plant responses to metal-stress by ROS and auxin signaling pathway, primarily, with a focus on the copper, aluminum and cadmium stress. The mechanisms underlying how metal stress modulates the changes in auxin distribution and the network of ROS and auxin in plant response to metal stress are discussed based on recent studies.…”

Changes in the size of the apparent surface area and adsorption energy of the rye roots by low pH and the presence of aluminium ions induced

“…In the acidic soils (pH <5), in the soil solution there are soluble compounds of aluminium. Among the soluble compounds of aluminium, inorganic monomeric forms and in particular Al 3+ and Al 13 are considered to be the most toxic forms (Horst et al, 2010;Panda et al, 2009;Silva, 2012). Aluminium toxicity is a global agricultural problem, severely limiting agricultural productivity for more than half of all the world arable land.…”

“…The studied species of plants had different resistance / sensitivity to the aluminium, while the rye used in the current studies (Secale cereale L.) has a very good tolerance for acidic ground. This grain has also a high tolerance for an aluminium and manganese ions (Ma et al, 2002;Panda et al, 2009). Learning the tolerant plants reactions to aluminium can contribute to a better understanding of the mechanisms responsible for tolerance to this metal at all.…”

“…The most recognized symptom of Al toxicity is the inhibition of root elongation (Azura et al, 2011). The toxic impact of aluminium on metabolic and physiological processes as well as morphological, biochemical and anatomical changes of plants has been demonstrated in many studies devoted to these issues (Darco et al, 2004;Panda et al, 2009). In addition, stress activates the roots of a series of defence mechanisms.…”

“…The main purpose of these mechanisms is to prevent the accumulation of the toxic concentrations of the metal in the sensitive areas of the root cell. Changes associated with toxicity aluminium, lead to inhibition of extracting and transport of water and ions in the roots (Panda et al, 2009). In many mathematical models describing the uptake of water and ions by the roots, the specific surface area is used (Ansari et al, 1995).…”