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Phosphorus (P), an essential macronutrient for various plant processes, is generally a limiting soil component for crop growth and yields. Organic and inorganic types of P are copious in soils, but their phyto-availability is limited as it is present largely in insoluble forms. Although phosphate fertilizers are applied in P-deficit soils, their undue use negatively impacts soil quality and the environment. Moreover, many P fertilizers are lost because of adsorption and fixation mechanisms, further reducing fertilizer efficiencies. The application of phosphate-solubilizing microorganisms (PSMs) is an environmentally friendly, low-budget, and biologically efficient method for sustainable agriculture without causing environmental hazards. These beneficial microorganisms are widely distributed in the rhizosphere and can hydrolyze inorganic and organic insoluble P substances to soluble P forms which are directly assimilated by plants. The present review summarizes and discusses our existing understanding related to various forms and sources of P in soils, the importance and P utilization by plants and microbes,, the diversification of PSMs along with mixed consortia of diverse PSMs including endophytic PSMs, the mechanism of P solubilization, and lastly constraints being faced in terms of production and adoption of PSMs on large scale have also been discussed. [ABSTRACT FROM AUTHOR]

Soils polluted with heavy metals result into various environmental and ecological tribulations like alterations in microbial community, deterioration of soil, and induction of metals into the human food chain. Noxious heavy metals, for instance, cadmium (Cd) and essential micronutrients like zinc (Zn) have identical chemical properties and are normally taken up by plants via similar carrier proteins as those of indispensable micronutrients. Cohesive interactions between plants and microbes and their co-existence or struggle for survival play a fundamental role in acclimatizing to metal-polluted environments. In this context, arbuscular mycorrhizal (AM) fungi are regarded as a prospective biotechnological approach for increasing tolerance of plants to heavy metal-polluted soils. However, the vital molecular factors responsible for regulating metal homeostasis/balance in these microbes have been poorly understood. Moreover, combined studies assessing the effect of AM fungal inoculation in alleviating Cd and/or Zn toxicity in plants and the underlying mechanisms are still unclear. This review presents the updated information on cross talk between Cd-Zn-AM in plants grown on agricultural and metal-contaminated soils. [ABSTRACT FROM AUTHOR]

The intent of the experiments was to analyze impact of cadmium (Cd) and/or zinc (Zn) on membrane functionality, nutrient acquisition, antioxidant defense, and osmolyte accumulation in nodules of two pigeonpea (Cajanus cajan(L.) Millsp.) genotypes (Sel 85N and P792) with and without arbuscular mycorrhizal (AM) fungusFunneliformis mosseae. Findings demonstrated that accumulation of Cd and Zn in nodules resulted in membrane destabilization, nutrient imbalance, increased antioxidant enzyme activities [superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and glutathione reductase (GR)], and osmoprotectants such as total free amino acids (FAA), total soluble sugars (TSS), proline, and glycine betaine (GB). Cd had higher negative effects than Zn. P792 was comparatively more metal sensitive and displayed higher reductions than Sel 85N. Application of Zn decreased Cd uptake and reduced the phytotoxic effects of Cd. Zn1000in combination withF. mosseaerestored nodular membrane stability; enhanced nutrient pool [phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe)]; and boosted antioxidant enzyme activities and osmolyte synthesis in a genotype-dependent manner. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) and zinc (Zn) are commonly associated with each other due to their similar geochemical behavior. Cadmium is a potentially toxic metal and Zn plays important role in counteracting Cd toxicity in plants. Arbuscular mycorrhizal (AM) fungi are known to be associated with plant metal tolerance. Aim of the study was to analyze Cd and Zn uptake and translocation and their impact on yield components in pigeonpea [Cajanus cajan (L.) Millsp.] genotypes under single and combined applications with and without Glomus mosseae. Cadmium and Zn contents varied greatly (roots > shoots > seeds). Yield parameters (number of flowers, seed weight, harvest index) were impaired with increasing Cd and Zn levels although Cd caused more reductions. ‘Sel 85N’ had lower metal accumulation and higher yield than ‘P792’. Combination of Cd25+Zn1000 was most effective in decreasing Cd uptake and increasing yield. Association with G. mosseae was significantly beneficial in ameliorating metal toxicity. [ABSTRACT FROM AUTHOR]