Agrobacterium-mediated transformation of mature embryos of Triticum aestivum and Triticum durum

Plant regeneration studies in cereals have been undertaken in immature embryos, scutellum and also in immature inflorescence tissue. The wheat mature embryos can also be employed for callusing and regeneration, as they are available throughout the year and have presently been employed for transformation studies. An efficient and reproducible method for Agrobacterium- mediated transformation of mature embryos of hexaploid bread wheat (Triticum aestivum) and tetraploid pasta wheat (Triticum durum) is reported. Presence of acetosyringone at 200 μ M concentration in the bacterial growth medium, inoculation medium and cocultivation medium was essential for achieving a 1.5- 2.0 fold increase in transient expression of the introduced gus gene. Successful generation of T. aestivum and T. durum transgenic plants at a transformation frequency ranging from 1.28 to 1.77% has been achieved following 2-3 days co-cultivation using mature embryos and also mature embryo-derived calluses with binary Agrobacterium strain LBA4404 (pBI101 :: Act1) and LBA4404 (p35SGUSINT) respectively. Paromomycin and phosphinothricin served as effective selection agents as they did not adversely affect plantlet regeneration. Successful integration as well as inheritance of the transgene was confirmed by Southern hybridization and PCR amplification in T0 as well as T1 generation. Optimization of this method facilitated the introduction of bar gene as a selectable marker conferring herbicide resistance as well as potato proteinase inhibitor gene (pin2) for insect resistance into wheat

Genetic approaches towards overcoming water deficit in plants-special emphasis on LEAs

Water deficit arises as a result of low temperature, salinity and dehydration, thereby affecting plant growth adversely and making it imperative for plants to surmount such situations by acclimatizing/adapting at various levels. Water deficit stress results in significant changes in gene expression, mediated by interconnected signal transduction pathways that may be triggered by calcium, and regulated via ABA dependent and/or independent pathways. Hence, adaptation of plants to such stresses involves maintaining cellular homeostasis, detoxification of harmful elements and also growth alterations. Stress in general cause excess production of reactive oxygen species (ROS) and the plants overcome the same by either preventing the accumulation of ROS or by eliminating the ROS formed. Ion homeostasis includes processes such as cellular uptake, sequestration and export in conjunction with long distance transport. Requisite amounts of osmolytes are hence synthesized under stress to maintain turgor along with maintaining the macromolecular structures and also for scavenging ROS. Another noteworthy response is the accumulation of novel proteins, including enzymes involved in the biosynthesis of osmoprotectants, heat-shock proteins (HSPs), late embryogenesis abundant (LEA) proteins, antifreeze proteins, chaperones, detoxification enzymes, transcription factors, kinases and phosphatases. The LEAs belong to a redundant protein family and are highly hydrophilic, boiling-soluble, non-globular and therefore have been defined and classified accordingly. The precise function of LEAs is still unknown, but substantial evidence indicates their involvement in dessication tolerance as the expression of LEAs confers increased resistance to stress in heterologous yeast system and also significantly improves water deficit tolerance in transgenic plants. Genetic manipulation of plants towards conferring abiotic stress tolerance is a daunting task, as the abiotic stress tolerance mechanism is highly complex and various strategies have been exploited to address and evaluate the stress tolerance mechanism, and the molecular responses to water deficit via complex signaling networks. Genomic technologies have recently been useful in integrating the multigenicity of the plant stress responses through, transcriptomics, proteomics and metabolite profilling and their interactions. This review deals with the recent developments on genetic approaches for water stress tolerance in plants, with special emphasis on LEAs

Efficacy of Green Synthesised Iron Oxide Nanoparticles against Various Uropathogens: A Cross-sectional Study

Introduction: The shoot up of antimicrobial resistance leading to the Multidrug Resistance (MDR) phenomenon in clinical pathogens has forced us to develop novel technologies to cease this global threat immediately. Iron oxide nanoparticles can be a breakthrough solution to this dilemma due to its magnetic properties and biocompatibility. Non toxic and biocompatible applications of magnetic nanoparticles can be enriched further by special surface coating with organic or inorganic molecules. Aim: To determine the antibacterial activity of green synthesised iron oxide nanoparticles against various clinical isolates. Materials and Methods: This was a cross-sectional study conducted from June 2021 to April 2022. This study was conducted at the Department of Microbiology, SRM Medical College Hospital and Research Centre (SRMMCH&RC), Kattankulathur, Chengalpattu, Tamil Nadu, India. Nanoparticles underwent surface modifications and characterisation using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX), Ultraviolet (UV) Visible Absorption Spectra, and Fourier-Transform Infrared Spectroscopy (FTIR) followed by charge characterisation through agarose gel electrophoresis. Kirby-Bauer Disc Diffusion method was used for screening the sensitivity and resistance pattern of 50 selected isolates and Minimum Inhibitory Concentration (MIC) was assessed using MIC Microbroth Dilution technique with the help of resazurin. Tukey post-hoc multiple comparisons test to analyse the zone of inhibition of antibacterial efficacy. Results: Out of the four different concentrations of bare and coated nanoparticles (0.0375 mg/mL, 0.07 mg/mL, 0.15 mg/mL, 0.3 mg/mL), bare nanoparticles inhibited the growth of Methicillin Resistant Staphylococcus aureus (MRSA) at 0.3 mg/mL while citrate coated nanoparticles inhibited the growth at 0.15 mg/mL, 0.018 mg/mL, 0.0375 mg/mL, 0.07 mg/mL, and 0.15 mg/mL dilutions were used in case of Carbapenem-resistant Klebsiella pneumoniae (CR K. pneumoniae) and MDR Escherichia coli, from which both organisms were inhibited at 0.15 mg/mL of bare and coated nanoparticles. Conclusion: Iron nanoparticles synthesised from the marine algae Chaetomorpha antennina could be used in the future as a drug carrier or as an antimicrobial agent