Deciphering metal toxicity responses of flax (Linum usitatissimum L.) with exopolysaccharide and ACC-deaminase producing bacteria in industrially contaminated soils

Nida Zainab; Amna; Bashir Ud Din; Muhammad Tariq Javed; Muhammad Siddique Afridi; Tehmeena Mukhtar; Muhammad Aqeel Kamran; Qurat Ul Ain; Amir Abdullah Khan; Javed Ali; Wajid Nasim Jatoi; Muhammad Farooq Hussain Munis; Hassan Javed Chaudhary

doi:10.1016/j.plaphy.2020.04.039

Deciphering metal toxicity responses of flax (Linum usitatissimum L.) with exopolysaccharide and ACC-deaminase producing bacteria in industrially contaminated soils

Plant Physiol Biochem. 2020 May 3:152:90-99. doi: 10.1016/j.plaphy.2020.04.039. Online ahead of print.

Affiliations

¹ Department of Plant Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
² Department of Botany, Government College University, 38000, Faisalabad, Pakistan.
³ Department of Plant Pathology, Federal University of Lavras, (UFLA), 37200-900, Larvas, MG, Brazil.
⁴ State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, PR China.
⁵ Department of Plant Biology and Ecology, Nankai University, Tianjin, PR China.
⁶ Department of Agronomy, Faculty of Agriculture & Environmental Sciences, The Islamia University of Bahawalpur, Punjab, Pakistan.
⁷ Department of Plant Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan. Electronic address: hassaan@qau.edu.pk.

PMID: 32408178
DOI: 10.1016/j.plaphy.2020.04.039

Abstract

Rapid industrialization is the main reason of heavy metals contamination of soil colloids and water reservoirs. Heavy metals are persistent inorganic pollutants; deleterious to plants, animals and human beings because of accumulation in food chain. The aim of the current work was to evaluate the role of indole acetic acid (IAA), exopolysaccharide (EPS) and ACC-deaminase producing plant growth promoting rhizobacteria (PGPR) i.e .B. gibsonii PM11 and B. xiamenensis PM14 in metal phytoremediation of metals, their survival and plant growth promotion potential in metal polluted environment as well as alterations in physio-biochemical responses of inoculated L. usitatissimum plants towards heavy metal toxicity. Two bacterial strains Bacillus gibsonii (PM11) and Bacillus xiamenensis (PM14), previously isolated from sugarcane's rhizosphere, were screened for metal tolerance (50 mg/l to 1000 mg/l) and plant growth promoting traits like IAA, ACC-deaminase, EPS production and nitrogen fixing ability under metal stress. The response of flax plant (Linum usitatissimum L.) was analyzed in a pot experiment containing both industrially contaminated and non-contaminated soils. Experiment was comprised of six different treatments, each with three replicates. At the end of the experiment, role of metal tolerant plant growth promoting bacterial inoculation was elucidated by analyzing the plant growth parameters, chlorophyll contents, antioxidative enzymes, and metal uptake both under standard and metal contaminated rhizospheres. Results revealed that root and shoot length, plant's fresh and dry weight, proline content, chlorophyll content, antioxidant enzymatic activity was increased in plants inoculated with plant growth promoting bacteria as compared to non-inoculated ones both in non-contaminated and industrial contaminated soils. In current study, inoculation of IAA, EPS and ACC-deaminase producing bacteria enhances plant growth and nutrient availability by minimizing metal-induced stressed conditions. Moreover, elevated phytoextraction of multi-metals from industrial contaminated soils by PGPR inoculated L. usitatissimum plants reveal that these strains could be used as sweepers in heavy metals polluted environment.

Keywords: ACC-Deaminase; B. gibsonii; B. xiamenensis; Exopolysaccharide; Flax; Industrial contamination.