Biotechnological Production of Plant-Based Insecticides

ABSTRACT:?

The demand for natural and nonpersistent insecticides is increasing day by day. Plant cell cultures could be an alternative to conventional methods of production of insecticides from field-grown plants. In vitro cultured plant cells produce a wide array of insecticides as a part of their secondary metabolism. Their ability to synthesize key enzymes and the manipulation of these could lead to the enhanced production of many insecticides of industrial importance. The development of a high-yielding hairy root culture system for thiophenes, nicotine, and phytoecdysones is of considerable interest. In this article, the current literature on various factors that influence the growth, production, and secretion of six insecticidal compounds, namely, pyrethrins, azadirachtin, thiophenes, nicotine, rotenoids, and phytoecdysones which have been prospects for the scale-up of cell cultures, genetic engineering to obtain transgenic plants, and metabolically engineered plants for increased production of bio-molecules, has been discussed. Environmental safety clearance and the future prospects of application of bio-molecules for plant-derived insecticides are presented.     

Novel Penicillin Analogues as Potential Antimicrobial Agents; Design,Synthesis and Docking Studies

A number of penicillin derivatives (4a-h) were synthesized by the condensation of 6-amino penicillinic acid (6-APA) with non-steroidal anti-inflammatory drugs as antimicrobial agents. In silico docking study of these analogues was performed against Penicillin Binding Protein (PDBID 1CEF) using AutoDock Tools 1.5.6 in order to investigate the antimicrobial data on structural basis. Penicillin binding proteins function as either transpeptidases or carboxypeptidases and in few cases demonstrate transglycosylase activity in bacteria. The excellent antibacterial potential was depicted by compounds 4c and 4e against Escherichia coli, Staphylococcus epidermidus and Staphylococcus aureus compared to the standard amoxicillin. The most potent penicillin derivative 4e exhibited same activity as standard amoxicillin against S. aureus. In the enzyme inhibitory assay the compound 4e inhibited E. coli MurC with an IC₅₀ value of 12.5 μM. The docking scores of these compounds 4c and 4e also verified their greater antibacterial potential. The results verified the importance of side chain functionalities along with the presence of central penam nucleus. The binding affinities calculated from docking results expressed in the form of binding energies ranges from -7.8 to -9.2kcal/mol. The carboxylic group of penam nucleus in all these compounds is responsible for strong binding with receptor protein with the bond length ranges from 3.4 to 4.4 Ǻ. The results of present work ratify that derivatives 4c and 4e may serve as a structural template for the design and development of potent antimicrobial agents.     

Biogeographical variation in community response to root allelochemistry: novel weapons and exotic invasion

Centaurea diffusa is one of the most destructive invasive weeds in the western USA and allelopathy appears to contribute to its invasiveness ( Callaway & Aschehoug 2000 ). Here we identify a chemical from the root exudates of C. diffusa, 8‐hydroxyquinoline, not previously reported as a natural product, and find that it varies biogeographically in its natural concentration and its effect as an allelochemical. 8‐Hydroxyquinoline is at least three times more concentrated in C. diffusa‐invaded North American soils than in this weed's native Eurasian soils and has stronger phytotoxic effects on grass species from North America than on grass species from Eurasia. Furthermore, experimental communities built from North American plant species are far more susceptible to invasion by C. diffusa than communities built from Eurasian species, regardless of the biogeographical origin of the soil biota. Sterilization of North American soils suppressed C. diffusa more than sterilization of Eurasian soils, indicating that North American soil biota may also promote invasion by C. diffusa. Eurasian plants and soil microbes may have evolved natural resistance to 8‐hydroxyquinoline while North American plants have not, suggesting a remarkable potential for evolutionary compatibility and homeostasis among plants within natural communities and a mechanism by which exotic weeds destroy these communities.     

Characterization of PR-10 genes from eight Betula species and detection of Bet v 1 isoforms in birch pollen

Background  

Bet v 1 is an important cause of hay fever in northern Europe. Bet v 1 isoforms from the European white birch (Betula pendula) have been investigated extensively, but the allergenic potency of other birch species is unknown. The presence of Bet v 1 and closely related PR-10 genes in the genome was established by amplification and sequencing of alleles from eight birch species that represent the four subgenera within the genus Betula. Q-TOF LC-MS^E was applied to identify which PR-10/Bet v 1 genes are actually expressed in pollen and to determine the relative abundances of individual isoforms in the pollen proteome.     

Performance of hairy root cultures of Cichorium intybus L. In bioreactors of different configurations

Summary A transformed root culture of Cichorium intybus L. cv. Lucknow Local grown in different configurations of bioreactors was examined. The roots grown in an acoustic mist bioreactor showed the best performance in terms of increased specific growth rate (0.072d⁻¹) and esculin content (18.5gl⁻¹), the latter of which was comparable to that of shake flask data. C. intybus hairy root cultures grown in an acoustic mist bioreactor produced nearly twice as much esculin as compared to roots grown in bubble column and nutrient sprinkle bioreactors. Studies relating to on-line estimation of conductivity and osmolarity to predict the growth of hairy root cultures are also discussed. The results demonstrate the efficacy and the advantages of an acoustic mist bioreactor for the cultivation of hairy root cultures, especially with reference to C. intybus hairy roots.     

In vitro propagation of Spilanthes mauritiana DC., an endangered medicinal herb, through axillary bud cultures

Summary Spilanthes mauritiana DC., (Compositae), a East African medicinal herb containing pharmaceutically promising secondary metabolites, has successfully been raised in vitro. We have developed a clonal propagation protocol that uses juvenile plants as starting material. The addition of benzylaminopurine (BA) (1.0 μM) and naphthaleneacetic acid (NAA) (0.1 μM) to the culture medium resulted in maximum shooting response with minimal callusing. Shoots rooted best in vitro in MS medium supplemented with indole-3-acetic acid (IAA; 0.2 μM), and plants that had already developed roots showed better growth, with maximum survival rate, in the greenhouse after an initial hardening.     

Global gene expression in rice blast pathogen Magnaporthe oryzae treated with a natural rice soil isolate

The rhizospheric microbiome is comprised of many microbes, some of which reduce the virulence of their phytopathogenic neighbors; however, the mechanisms underlying these interactions are largely unknown. Rice soil isolate Pseudomonas chlororaphis EA105 strongly inhibits Magnaporthe oryzae’s in vitro growth by restricting fungal diameter as well as inhibiting the formation of the appressorium, required for penetration. We were interested in elucidating M. oryzae’s response to EA105 treatment, and utilized a microarray approach to obtain a global perspective of EA105 elicited changes in this pathogen. Based on this analysis, three genes of interest were knocked out in M. oryzae 70-15, and their sensitivity to EA105 treatment as well as their ability to infect rice was determined. Priming rice plants with EA105 prior to M. oryzae infection decreased lesion size, and the mutants were tested to see if this effect was retained. A null 70-15 mutant in a trichothecene biosynthesis gene showed less susceptibility to bacterial treatment, forming more appressoria than the parental type 70-15. A similar pattern was seen in a null mutant for a stress-inducible protein, MGG_03098. In addition, when this mutant was inoculated onto the leaves of EA105-primed rice plants, lesions were reduced to a greater extent than in 70-15, implicating the lack of this gene with an increased ISR response in rice. Understanding the global effect of biocontrol bacteria on phytopathogens is a key for developing successful and lasting solutions to crop loss caused by plant diseases and has the potential to greatly increase food supply.