School Of Basic And Applied Sciences

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    Transcriptomic investigations of gene networks in response to arsenic accumulation in Brassica juncea (L.) Czern & Coss
    (Central University of Punjab, 2019) Thakur, Sapna; Bhardwaj, Pankaj
    Arsenic (As), a widespread toxic metalloid is class I carcinogen known to cause adverse health effects in human. In the present study, As accumulation potential and differential gene expression in B. juncea is investigated. The amount of arsenic accumulated varied in the range of 15.99 to 1138.70 mg/Kg on dry weight basis in five cultivars. A decrease in chlorophyll content and increase in membrane damage and enzymatic activities of antioxidants was observed with increase in As concentration in the B. juncea cultivars. Using maximum As accumulating cultivar (RLM514), a total of 10,870 significantly differentially expressed transcripts in response to As treatment were identified. Further, the pathway analysis revealed a large scale reprogramming of genes involving carbon metabolism (2.5%), plant hormone signaling (1.4%), and glutathione metabolism (0.6%). Moreover, a comparative account of Cd toxicity revealed a total of 11,294 transcripts to be significantly differentially expressed. The genes related to response to chemical, oxidative stress, transport, and secondary metabolism were upregulated whereas multicellular organismal development, developmental process, photosynthesis were downregulated by Cd treatment. Furthermore, 616 membrane transport proteins were found to be significantly differentially expressed. Cd-related transporters such as metal transporter (Nramp1), metal tolerance protein (MTPC2, MTP11), cadmiumtransporting ATPase, and plant cadmium resistance protein (PCR2, PCR6) were upregulated while cadmium/zinc- transporting ATPase (HMA2, HMA3, HMA4), highaffinity calcium antiporter (CAX1), and iron transport protein (IRT1) were downregulated by Cd treatment. Pathway analysis revealed signaling cascades including plant hormones signaling, MAPK signaling and Ca signaling was modulated suggesting their role in Cd-stress tolerance. The regulation overview using MapMan also revealed gene expression related to plant hormones, calcium regulation and MAP kinases were altered under Cd-stress.
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    Insights into the Molecular Mechanism of Arsenic Phytoremediation
    (Springer New York LLC, 2019) Thakur S.; Choudhary S.; Majeed A.; Singh A.; Bhardwaj P.
    Arsenic (As) is a widespread carcinogenic pollutant. Phytoremediation is the most suited technology for alleviating the As contamination of soil. In this review, we have discussed the uptake mechanism and the associated transporters for different As species. Glutathione, phytochelatins, metallothionins, and secondary metabolites play important role in As detoxification and enhancing tolerance. The roles of MAPK signaling and calcium signaling are highlighted in the perception of As stress along with phytohormones signaling in stress tolerance. Furthermore, transcription factors involved in regulation of gene expression under As stress are discussed. High-throughput sequencing has reduced the time duration and enhanced the knowledge regarding understanding the molecular mechanism of phytoremediation. The role of CRISPR/Cas9 and synthetic genes in context to phytoremediation is discussed. We have provided a holistic understanding of the present knowledge about phytoremediation in the context of mechanisms of the As uptake and tolerance. A complete understanding of the phytoremediation process is essential for As-risk mitigation and will help in augmenting its efficiency and true potential.
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    Pseudomonas citronellolis; a multi-metal resistant and potential plant growth promoter against arsenic (V) stress in chickpea
    (Elsevier, 2019) Adhikary, Arindam; Kumar, R; Pandir,R; Bhardwaj, Pankaj; Wusirika, Ramakrishna; Kumar, Sanjeev
    Soil micro-biota plays a vital role in maintaining plant growth and fitness under normal and adverse conditions. Pseudomonas is one of the most important free-living and copious genera in south-west Punjab and involved in plant growth promotion under heavy metal stress. In this study, we have studied microbial diversity of the agricultural and marginal land based on 16S rRNA gene and screened eight strains of Pseudomonas for its tolerances towards various heavy metals and for plant growth promoting properties (PGP). The best strain is tested in chickpea plants against Arsenic (As5+) stress. All the strains responded differently to heavy metals viz. Arsenic, (As5+ (0.3–0.5M) and As3+ (250 μg mL−1) Cadmium (Cd2+) (250–350 μg mL−1), Chromium (Cr2+) (200–350 μg mL−1) and Mercury (Hg2+) (1–2 μg mL−1). Out of eight strains, only two strains (KM594398 and KM594397) showed plant growth promoting characters, concurrently they were highly tolerant to Arsenic (As5+). Pseudomonas citronellolis (PC) (KM594397) showed the best results in terms of As5+ tolerance and plant growth promoting activity, hence further tested for actual plant growth response in chickpea (Cicer arietinum L.) under As5+ (10–160 mg kg−1) stress. Pseudomonas citronellolis enhanced plant growth and dry biomass under As5+ stress. High As5+ tolerance and plant growth promoting activity of Pseudomonas citronellolis in chickpea especially designate this strain suitable for marginal lands and heavy metals contaminated sites. © 2019 Elsevier Masson SAS