Interactions between plants and associated bacteria in soils contaminated with heavy metals

Mechanisms of plant and microbial adaptation to heavy metals in plant–microbial systems

“…Our suggestion was confirmed by the increased population level of bacteria (2.5-to 7-fold) in the barley plant rhizoplane under exposure to Pb 2+ (200 mg/kg) and Cd 2+ (50 mg/kg), compared to the variant without HM (Pishchik et al, 2009). With time, the population level on the roots reached an equilibrium state due to migration of a part of the population to the rhizosphere.…”

“…The increase in the number of bacteria in the rhizosphere as a result of their migration from the rhizoplane was accompanied by a proportional increase in free HM ions (Cd 2+ and Pb 2+ ) bound in chelate complexes and unavailable to plants. As a consequence, the HM uptake by plants considerably decreased (4-6 times, respectively) (Pishchik et al, 2009) (Fig. 2).…”

“…Some research works have shown that rhizospheric bacteria can both increase and decrease the HM bioavailability to plants, which leads to an increase (Abou-Shanab et al, 2003) or decrease (Pishchik et al, 2009;Agnello et al, 2015) in the uptake of these elements by plants. The PGPR bacteria present in the rhizosphere of the hyperaccumulator Thalaspi caerulescens produced organic acids and acidified the medium, increasing the number of bioavailable Ni 2+ ions and, as a consequence, their uptake by plants (Whiting et al, 2001;Abou-Shanab et al, 2003).…”

“…Due to their physiological properties, microorganisms are capable of fairly rapid reproduction, rearrangement of their enzymatic apparatus (Ruchko, 1984;Pishchik et al, 1997), and migration from one root niche to another (Pishchik et al, 1998). Hence, PMS and both of its components (plants and microorganisms) survive and function under stress conditions, including those under the influence of high HM concentrations (Pishchik et al, 2009). This review is devoted to the mechanisms of HM detoxification and resistance in plants and bacteria, the role of bacteria in the adaptation of plant/microbial systems to HM, and the strategy of PMS survival in HM-polluted soil.…”

Induction of salt tolerance and up-regulation of aquaporin genes in tropical corn by rhizobacterium Pantoea agglomerans

“…Several strains of Pantoea agglomerans have been studied for their effects on temperature tolerance of wheat ( Triticum aestivum ) and heavy metal tolerance of oat ( Avena sativa ) (Egamberdiyeva and Hoflich ; Pishchik et al . ). Elevated salt in soil leads to water scarcity in the plant's rhizosphere, which leads to physiological and biochemical changes in the root.…”