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Plant Growth–Promoting Rhizobacteria (PGPR) and Bioremediation of Industrial Waste
Published in Ram Chandra, R.C. Sobti, Microbes for Sustainable Development and Bioremediation, 2019
Sangeeta Yadav, Kshitij Singh, Ram Chandra
The success of remediation through plant is dependent on the potential of the plants to yield high biomass and withstand under stress condition. Plant hormones are chemical messengers that influence the plant’s ability to react to its environment. These are naturally organic compounds that are effective at very low concentration and are mostly synthesized in certain parts of the plant and transported to another location. Plant hormones, also referred to as phytohormones, influence physiological processes at low concentrations. Auxin is a class of plant hormones important in the promotion of lateral root formation. Increased lateral root formation leads to an enhanced ability to take up nutrients and pollutants by the plant. Indole-3-acetic acid (IAA) is the most common, naturally occurring, plant hormone of the auxin class. It is the best known of the auxins. IAA is the foremost phytohormone that accelerates plant growth and development by improving root/shoot growth and seedling vigor. IAA is involved in phototropism and geotropism, cell division, vascular bundle formation, vascular tissue differentiation, apical dominance, root initiation (lateral and adventitious), stem and root elongation, and an essential hormone for nodule formation.
Beneficial Microorganisms and Abiotic Stress Tolerance in Plants
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
Antra Chatterjee, Alka Shankar, Shilpi Singh, Vigya Kesari, Ruchi Rai, Amit Kumar Patel, L.C. Rai
Plant growth and development is linked to several phytohormones (auxins, gibberellins, cytokinins, ethylene and abscisic acid) controlling cell elongation, cell division and re-orientation of growth (Farooq et al., 2009). Auxins, especially indole-3-acetic acid (IAA), has a strong influence on plant development and in particular on lateral root formation and branching. The increment in root length and modifications of the root architecture were correlated with increased IAA concentrations in PGPR-treated plants (Contesto et al., 2010). Increased root and shoot biomass and water content under abiotic stress have been reported in clover plants treated with PGPR, which was linked with increased IAA production (Marulanda et al., 2009). Treatment of Arabidopsis plants with PGPR Phyllobacterium brassicacearum strain STM196 resulted in increased lateral root length and modifications of the root architecture that led to the observed abiotic stress tolerance (Bresson et al., 2014).
Turfgrass Physiology and Environmental Stresses
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
Auxins. The discovery of auxin (from the Greek auxein, meaning “to increase” or “to grow”) can be traced to the observations of Darwin (around 1880), who was investigating the phototropic curvature of grass seedlings’ coleoptiles. Went (1926) later found evidence leading to the physiological proof of auxin as a plant growth substance. It is produced in meristematic or other actively growing tissue, moves throughout the plant, and is capable, in minute concentrations, of affecting elongation in cells below this meristem or site of production. Indole-3-acetic acid (IAA) is the primary plant auxin. Other auxin-like compounds include phenylacetic acid, indole-3-butyric acid (IBA), naphthalene acetic acid (NAA), and 2,4-dichlorophenoxy acetic acid (2,4-D).
Heavy metal (loid)s phytotoxicity in crops and its mitigation through seed priming technology
Published in International Journal of Phytoremediation, 2023
Rajesh Kumar Singhal, Mahesh Kumar, Bandana Bose, Sananda Mondal, Sudhakar Srivastava, Om Parkash Dhankher, Rudra Deo Tripathi
Phytohormones and various plant growth regulators are reported to regulate the stress responses including HMs toxicity in crops. Munzuroglu and Zengin (2006) demonstrated the role of GA and kinetin under Cd stress and reported that priming improved seed germination, coleoptile, and root growth of barley seeds. Likewise, 0.1 mM gibberellic acid (GA) priming of Trifolium repens improved germination and early seedling growth in Cd and Zn polluted soil (Galhaut et al. 2014). Additionally, Hassan and Mansoor (2017) found that priming with 50 µM SA and 100 µM GA phytohormone alleviated Cd toxicity in the mungbean. In this array, Sneideris et al. (2015) used different phytohormones, such as auxin, GA, cytokinin, ABA, and ethylene as priming agents in the presence of Cd as a stressor in pigeon pea (Cajanus cajan) and revealed that primed seeds perform well as compared to the controls. Recently, Sytar et al. (2019) reviewed the role of phytohormone priming with respect to HMs stress, they clarified the behavior of phytohormones under HMs stress environment and also explained the toxicity of HMs and its mechanism of action. Moreover, Agami and Mohamed (2013) depicted the role of indole-3-acetic acid in alleviating Cd stress in wheat.
Impacts of root pruning intensity and direction on the phytoremediation of moderately Cd-polluted soil by Celosia argentea
Published in International Journal of Phytoremediation, 2022
Youjun Tang, Tian Gan, Min Cao, Jinnuo Song, Dan Chen, Jie Luo
Root pruning is a common agronomic management practice. The application of this practice can remove the apical dominance that impedes the development of lateral roots, thereby increasing the biomass yield, water use efficiency, and nutrient uptake capacity of plants (Valdés-Rodríguez and Pérez-Vázquez 2019). However, there are conflicting results from previous studies regarding the impacts of root cutting of different plants. Generalized statements are not accurate because multiple factors can influence the responses of plants to root pruning. Physiological responses depend on the type of species, pruning deposition, pruning time, pruning size, and pruning intensity. For example, low pruning intensity results in high root vigor in Ricinus communis L.; contrastingly, the severity of root pruning increases the rooting ability of Pyrus communis L. Moreover, suitable pruning practices can disrupt the physiological equilibrium of plants and change the hormone levels in their tissues. Feng et al. (2018) reported that the content of indole-3-acetic acid, which is a type of plant hormone that stimulates the growth rate of plants, increased in Platycladus orientalis L. Franco roots when the taproots were removed. In addition, the loss of roots is inevitable during the transplanting process, which is an important procedure of phytoremediation because the integrity of the roots could be damaged to varying degrees when excavating the cultivated plants from the soil.
Fabrication and characterization of nano-hydroxyapatite particles and assessment of the effect of their supplementation on growth of bacterial root endosymbionts of cowpea
Published in Inorganic and Nano-Metal Chemistry, 2022
Simranjot Kaur, Anu Kalia, Sat Pal Sharma
Another prominent PGP trait, Indole-3-acetic acid (IAA) production potential of the promising isolates was also evaluated. Bacterial synthesis and secretion of IAA affects several root-related processes such as the root initiation, cell division, cell enlargement, root growth, and enhancement of the root length, resulting in greater root surface area which enables the plant to access more nutrients from soil.[49] Five bacterial cultures were assessed for their natural ability to produce IAA both in the presence and absence of the precursor L-Tryptophan. Considerable variation in the ability to produce IAA by different bacterial isolates was observed. Indole acetic acid production ranged from 9.21 ± 0.23 to 80.12 ± 0.2 µg mL−1. Maximum IAA production was observed in isolate CP-RN-4 and the reference culture Bradyrhizobium sp. NAIMCC-B-00260 (Figure 3).