Alleviation of heavy metals toxicity by the application of plant growth promoting rhizobacteria and effects on wheat grown in saline sodic field

Abstract

The aim of the study was to determine tolerance of plant growth promoting rhizobacteria (PGPR) in different concentrations of Cu, Cr, Co, Cd, Ni, Mn, and Pb and to evaluate the PGPR-modulated bioavailability of different heavy metals in the rhizosphere soil and wheat tissues, grown in saline sodic soil. Bacillus cereus and Pseudomonas moraviensis were isolated from Cenchrus ciliaris L. growing in the Khewra salt range. Seven-day-old cultures of PGPR were applied on wheat as single inoculum, co-inoculation and carrier-based biofertilizer (using maize straw and sugarcane husk as carrier). At 100 ppm of Cr and Cu, the survival rates of rhizobacteria were decreased by 40%. Single inoculation of PGPR decreased 50% of Co, Ni, Cr and Mn concentrations in the rhizosphere soil. Co-inoculation of PGPR and biofertilizer treatment further augmented the decreases by 15% in Co, Ni, Cr and Mn over single inoculation except Pb and Co where decreases were 40% and 77%, respectively. The maximum decrease in biological concentration factor (BCF) was observed for Cd, Co, Cr, and Mn. P. moraviensis inoculation decreases the biological accumulation coefficient (BAC) as well as translocation factor (TF) for Cd, Cr, Cu Mn, and Ni. The PGPR inoculation minimized the deleterious effects of heavy metals, and the addition of carriers further assisted the PGPR.

Genome sequencing and assessment of plant growth-promoting properties of a Serratia marcescens strain isolated from vermicompost

“…Successful soil bacteria often have to tolerate metal contamination, which can involve different 313 strategies (Das et al 2016). In addition, PGPR can alleviate the impact of heavy metals on plants by 314 reduction, oxidation, methylation and conversion to less toxic forms (Hassan et al 2017). We found a 315 number of genes related to these roles in the SMU genome (Table 1): arsenate reductase 316 (AK961_01055), arsRBC (AK961_03990, AK961_03995, AK961_04000), copper resistance protein 317 (AK961_01905, AK961_01915, AK961_09290), cusRS (AK961_11430, AK961_11425), chromate 318…”

Complete Genome Sequence of Pseudomonas psychrotolerans CS51, a Plant Growth-Promoting Bacterium, Under Heavy Metal Stress Conditions

“…These microorganisms are found predominantly in the rhizosphere. In the literature, PGPR have been reported to alleviate heavy metal stress through several mechanisms such as mobilization, immobilization, and heavy metal transformation [9]. Furthermore, various PGPR present in the soil around plant roots can facilitate plant growth either by producing various plant growth regulators or providing and facilitating nutrients uptake [10].…”

Changes in leaf morphological and anatomical characters of some plant species in response to gemstone mining in southwestern Nigeria

“…The decrease in the size of stomata is thought to be an avoidance mechanism against the inhibitory effect of pollutants on physiological activities of the plant such as photosynthesis (Gomes et al, 2011). These modifications are important response to the environmental stress which affected plants used in controlling the absorption of pollutants (Gostin, 2009;Hassan et al, 2017). The decrease observed in the sizes of stomatal aperture as a response to heavy metal pollution is in line with the hypothesis that metals induce water stress (Rucin´ska-Sobkowiak, 2016).…”

“…Where such metals are present at high concentrations, they can act in a deleterious manner to plants. Uptake and accumulation of some metals at higher concentration can have cytotoxic effects in some plants species, thereby causing structural and ultra-structural changes which can affect growth and physiological well-being of plants (Panuccio et al, 2009;Hassan et al, 2017). For example, studies have shown that excessive concentrations of heavy metals in plants can cause oxidative stress and stomatal resistance (Zhao et al, 2000;Han et al, 2004).…”