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Bacterial Synthesis of Metallic Nanoparticles
Published in Ramesh Raliya, Nanoscale Engineering in Agricultural Management, 2019
Shweta Agrawal, Mrinal Kuchlan, Jitendra Panwar, Mahaveer Sharma
Intuitively, nanoparticles can be used as biomarkers or as a rapid diagnostic tool for detection of bacterial, viral and fungal plant pathogens. Researchers have used nano-gold based immuno-sensors that could detect Karnal bunt (Tilletia indica) disease in wheat using surface plasmon resonance (SPR). Additionally, plants respond to different stress conditions through physiological changes such as induction of systemic defence, probably regulated by plant hormones: Jasmonic acid, methyl jasmonate and salicylic acid. This indirect stimulus was successfully harnessed in order to develop a sensitive electrochemical sensor, using modified gold electrode with copper nanoparticles, to monitor the levels of salicylic acid in the oil seeds to detect the fungi (Sclerotinia sclerotiorum). Researches on similar sensors and sensing techniques needs to be expanded for detecting pathogens, their by-products, or monitor physiological changes in plants and then apply pesticides and fertilizers as needed prior to the onset of symptoms (Khot et al. 2012). A mixture of titanium dioxide, aluminium and silica was reported to effectively control downy and powdery mildew of grapes, probably through direct action on the hyphae, interference with fungal mechanism of recognition of plant surface and stimulation of plant physiological defences. A new composition of nano-silver combined with silica molecules and water-soluble polymer proved effective in suppressing the growth of many plant pathogenic fungi and bacteria. Pythium ultimum, Magnaporthe grisea, Colletotrichum gloeosporioides, Botrytis cinere and Rhyzoctonia solani showed 100% inhibition of growth at 10 ppm concentration; whilst, Bacillus subtilis, Azotobacter chrococuum, Rhizobium tropici, Pseudomonas syringae, Xanthomonas compestris pv. and Vesicatoria showed 100% growth inhibition at 100 ppm concentration of the nanosized silica-silver (Sharon et al. 2010, Mishra and Singh 2014).
Bioengineering Approach on Terpenoids Production
Published in Dijendra Nath Roy, Terpenoids Against Human Diseases, 2019
Diterpenoids have attracted rising consideration for their remarkable biological and pharmacological activities, for example, the production of the anti-cancer compound Taxol® (paclitaxel), fragrance ingredient labdanoid sclareol, anti-oxidants carnosic acid and carnosol. To increase the yield and diversity of these diterpenoids, metabolic engineering models in microbial or plant hosts have been tested. Nicotiana benthamiana transiently transformed with Cembratriene-ol synthase from Nicotiana sylvestris, casbene synthase from Ricinus communis and levopimaradiene synthase from Gingko biloba accumulated diterpenoids during first 3 days of infiltration, with maximum levels peaking at 5 days. The co-expression of tomato DXS and tobacco GGPS resulted in a 3.5-fold intensification in cembratrien-ol levels, with a maximum yield of 2,500 ng/cm2 (Bruckner and Tissier 2013). The co-expression of the SmHMGR and/or the SmGGPPS gene, as well as the SmDXS gene, in Salvia miltiorrhiza hairy root lines led to significant enrichment of abietane-type diterpenoid tanshinone that has antibacterial, anti-inflammatory and broad antitumor activities (Kai et al. 2011). Another approach that has been utilized to increase terpenoids is the usage of jasmonate hormone and its biosynthetic genes. The jasmonate pathway induces terpenoid biosynthesis in plants in response to pathogen attack or herbivore feeding. The allene oxide cyclase (AOC) gene, responsible for the key enzyme of the jasmonate biosynthetic pathway on overexpression, considerably enhanced expression of many diterpenoids biosynthetic pathway genes. This caused an increase in tanshinone IIA, rosmarinic acid and lithospermic acid B production in S. miltiorrhiza hairy root cultures (Gu et al. 2012). With regards to paclitaxel engineering, the initial enzyme catalysing the first step of paclitaxel biosynthesis, taxadiene synthase gene (TXS) was overexpressed in Arabidopsis and N. benthamiana. Taxadiene accumulation of 20 ng/g DW in Arabidopsis and 11–27 μg/g DW in Nicotiana was reported (Besumbes et al. 2004; Hasan et al. 2014; Lu et al. 2016). Constitutive expression of TXS by Taxus brevifolia in the moss Physcomitrella patens (Hedw.), known for producing diterpenoids derived from ent-kaurene, led to taxa-4(5),11(12)-diene production of up to 0.05% of fresh weight of tissue (Anterola et al. 2009). Paclitaxel production by plant metabolic engineering has been extensively reviewed by Kundu et al. (2017).
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
Jasmonic acid (JA) has a regulatory role in plant growth, development, and stress protection. JA and its active derivatives (jasmonates) modulate a range of defense responses against various stresses (Wasternack 2007). Sharma et al. (2013) discussed the role of JA on photosynthetic pigments and stress markers in pigeon pea seedlings under Cu stress. Sirhindi et al. (2016) noted that Ni toxicity modulates the seedling’s shoot and root weights, chlorophyll content, metabolite, and antioxidant enzymes gene expression in soybean, which could be alleviated by using JA as seed primer. Furthermore, Mir, Sirhindi et al. (2018) depicted the role of JA seed priming in improving growth attributes under Ni toxicity in the soybean. They found that JA improved the antioxidant enzyme, redox status, ROS, and regulated the uptake of Ni. Recently, reported that JA priming declines levels of MDA, O2•−, and H2O2, and decreases membrane and nuclear damage in tomatoes. They also found that RBO (Rubredoxin oxidoreductase) and P-type ATPases transporter genes under Pb stress, which reduce the translocation of Pb in the seedlings. Moreover, JA seed priming improves the photosynthetic activity, ascorbate-glutathione pathway, secondary metabolite, and enhances osmolytes and metal chelating compounds production under Pb stress (Bali, Jamwal, Kaur, et al. 2019; Bali, Jamwal, Kohli, et al. 2019).
Alleviation of boron toxicity in plants: Mechanisms and approaches
Published in Critical Reviews in Environmental Science and Technology, 2021
Tianwei Hua, Rui Zhang, Hongwen Sun, Chunguang Liu
Besides nutrient elements, some exogenous chemicals (some can be naturally produced by the plant) were also found to alleviate B toxicity in plants via triggering ROS scavenging mechanisms (Table 2). For example, some plant growth regulators (PGRs) (e.g. salicylic acid, nitric oxide, methyl jasmonate) have been reported to mediate antioxidative systems of plants under B stress. Salicylic acid (SA), a hormone-like substance playing an important role in plant growth regulation, has been found to regulate antioxidant enzymes in carrot, spinach, barley, and wheat exposed to excess B (Eraslan et al., 2007; Eraslan et al., 2008; El-Feky et al., 2014; El-Shazoly et al., 2019). In recent years, nitric oxide (NO), an important signaling molecule in plants, has been observed to help plant tolerate excess B via regulating antioxidant enzymes (Aftab et al., 2012; Esim & Atıcı, 2013; Kaya & Ashraf, 2015; Farag et al., 2017; Dilek Tepe & Aydemir, 2017; Kaya et al., 2019). Jasmonic acid (JA) and its methyl ester, methyl jasmonate (MeJA), are important plant hormones and signal molecules. Both the two hormones have been reported to be able to improve plant tolerance to high levels of B by regulating antioxidant enzyme activities (Aftab et al., 2011; Sarabandi et al., 2019; Zhao et al., 2019).
Effect of Ozone Treatments on Germination and Disinfection of Sacha Inchi (Plukenetia volubilis L.) Seeds
Published in Ozone: Science & Engineering, 2023
MAYRA Bataller Venta, ELIET Veliz Lorenzo, ALEXANDER Perez, GRETHER Barreras, MABEL Villanueva, NIUBIS Ortega, OSCAR Ledea
The greater resistance to fungal attack in T1 may be due to the increase of jasmonic acid (JA), which allows a greater defensive response against pathogen attack (Ren et al. 2015). Bhavanam and Stout (2021) report that jasmonates play a critical role in plant resistance against insect pests, pathogens, and abiotic stress. These authors obtained favorable results in treated rice seeds and evaluated the affectation on the growth and development of the plants.