In this Review, an effort is made to discuss the most recent progress and future trend in the two‐way traffic of the interactions between plants and nanoparticles (NPs). One way is the use of plants to synthesize NPs in an environmentally benign manner with a focus on the mechanism and optimization of the synthesis. Another way is the effects of synthetic NPs on plant fate with a focus on the transport mechanisms of NPs within plants as well as NP‐mediated seed germination and plant development. When NPs are in soil, they can be adsorbed at the root surface, followed by their uptake and inter/intracellular movement in the plant tissues. NPs may also be taken up by foliage under aerial deposition, largely through stomata, trichomes, and cuticles, but the exact mode of NP entry into plants is not well documented. The NP–plant interactions may lead to inhibitory or stimulatory effects on seed germination and plant development, depending on NP compositions, concentrations, and plant species. In numerous cases, radiation‐absorbing efficiency, CO2 assimilation capacity, and delay of chloroplast aging have been reported in the plant response to NP treatments, although the mechanisms involved in these processes remain to be studied.

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metal solution, reduction of the metal ions leads to the generation of metal atom clustering generating nanosized particles. A characteristic of biosynthetic NPs is their high stability as the organisms provide their own biomolecular capping agent(s). [1] While plant-based production of NPs is now considered a scientific curiosity rather than a promising biotechnology, [2] bacteriamediated NP biosynthesis offers better chances, in light of the poorly characterized microbial diversity and the complex chemistry of enzymes in metal-reducing bacteria. Two recent works focused on directed biofabrication of CdSe-nanoparticles through regulating extracellular electron transfer [3] and the biosynthesis of highly active copper NPs (CuNP) by Shewanella oneidensis. [4] However, the description of molecular mechanism(s) involved in the biosynthesis of NPs has received little attention, which is the focus of this review.The CFCF or culture supernatants (CS) of bacteria mediate the synthesis of AgNPs [5] as presented in this section. The CFCF from the family Enterobacteriaceae reduce silver ions to AgNPs ( Table 1). CFCF of Klebsiella pneumoniae, Escherichia coli, and Metal nanoparticles (NPs), chalcogenides, and carbon quantum dots can be easily synthesized from whole microorganisms (fungi and bacteria) and cell-free sterile filtered spent medium. The particle size distribution and the biosynthesis time can be somewhat controlled through the biomass/metal solution ratio. The biosynthetic mechanism can be explained through the ionreduction theory and UV photoconversion theory. Formation of biosynthetic NPs is part of the detoxification strategy employed by microorganisms, either in planktonic or biofilm form, to reduce the chemical toxicity of metal ions. In fact, most reports on NP biosynthesis show extracellular metal ion reduction. This is important for environmental and industrial applications, particularly in biofilms, as it allows in principle high biosynthetic rates. The antimicrobial and antifungal effect on biosynthetic NPs can be explained in terms of reactive oxygen species and can be enhanced by the capping agents attached to the NP during the biosynthesis process. Industrial applications of NP biosynthesis are still lagging, due to the difficulty of controlling NP size and low titer. Further, the environmental assessment of biosynthetic NPs has not yet been carried out. It is expected that further advancements in biosynthetic NP research will lead to applications, particularly in environmental biotechnology.

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Surveys of major rice growing districts in the state of Uttar Pradesh in Northern India were conducted for 3 consecutive years during 2013 to 2015 under a government-funded major research project to determine the frequency of occurrence and disease incidence of the rice root-knot nematode, Meloidogyne graminicola, in rice paddy fields. More than 800 paddy fields from 88 Tehsils (divisions within a district) in 18 major rice growing districts in Uttar Pradesh were surveyed, where M. graminicola was associated with root-knot disease in rice paddy fields based on morphological and molecular characterization of juveniles and adults. The highest frequency of disease in rice fields was observed in Aligarh (44.6%), followed by Muzaffarnagar, Shahjahanpur, and Kheri Lakhimpur (29.3, 28.0, and 27.4%, respectively). Maximum disease incidence was also recorded in Aligarh (44.6%), followed by Sultanpur, Mainpuri, and Muzaffarnagar (5.7, 5.2, and 4.5, respectively). Gall index and egg mass index values (on a 0 to 10 scale) were highest in Aligarh (3.5 and 2.1, respectively), followed by Muzaffarnagar (2.6 and 2.0) and Mainpuri (2.3 and 1.8). The average soil population of M. graminicola was highest in Aligarh (3,851 ± 297 second-stage juveniles [J2]/kg of soil), followed by Muzaffarnagar (2,855 ± 602 J2/kg of soil), whereas the lowest population was recorded in Barabanki (695 ± 400 J2/kg of soil) at the time of harvesting. Relative yield losses were also determined, and the highest yield loss attributed to M. graminicola infestation was recorded in Aligarh (47%). The yield loss was linearly correlated with the soil population density of M. graminicola and disease incidence.

A disease survey was conducted in the green gram (Vigna radiata) growing areas of Bharuch, Gujarat, India in February 2020. Root rot was observed on cultivar NVL-585 in 30 fields surveyed, with 15 to 20% of disease incidence. Infected plants showed foliar chlorosis, brown discoloration, dark black brittle roots with necrotic lesions, and dead plants. The root rot causal agent was isolated on potato dextrose agar (PDA) from 25 symptomatic samples collected from 10 diseased plants and pure cultures were obtained using single hyphal tip method. The cultures were grayish black with a smooth texture. Conidia were single celled, elliptical to oval in shape and were 5.2 to 6.5μm (n=25) in length and 2.7 to 3.4µm in width. Plastic pots (15 cm in diameter) were filled with autoclaved soil (1.5 kg/pot) inoculated with a 15-day-old culture of the fungus at 3 g/ kg (108 cfu/g). After 7 days, the local green gram cultivar HUM 16 was sown into the pots. Seedlings were thinned to 10 for each pot. Chlorosis of leaves, rotting roots, and even plant death were observed at 20, 30 and 40 days after seeding. The experiment was conducted twice to fulfill the Koch postulates. The fungus was reisolated from the root rot samples, and identical colony morphology was observed as seen previously. Based on the cultural characteristics and conidial morphology, the fungus belonged to Ectophoma sp. (Boerema et al. 2004). ITS, D1 and D2 regions of LSU and β-tubulin were used for molecular identification. The BLASTn analysis of ITS, D1 and D2 region of LSU gene and β-tubulin gene sequences of Isolate G80 showed a 100% similarity with accession number MH858623 (Vu et al. 2019), 99.82% similarity with MH870612 (Vu et al. 2019) and 100% similarity with MN983939 (Hou et al. 2020). Gene sequence has been submitted to NCBI GenBank, and accession numbers for ITS, D1 and D2 region of LSU and β-tubulin are MW165415, MW813868 and LC656357, respectively. The pathogen was previously reported from other hosts like Fuchsia× hybrida, Origanum vulgare, Lavandula angustifolia, Cicer arietinum and Coriandrum sativum. It can cause substantial economic damage to a wide range of commercially important crops. To the best of our knowledge, this is the first report of E. multirostrata causing root rot disease of green gram in India.