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Bioprospecting of Microbial Diversity for Sustainable Agriculture and Environment
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Hiren K. Patel, Nensi K. Thumar, Priyank D. Patel, Azaruddin V. Gohil
N-acyl-L-homoserine lactones (AHLs) are molecules involved in quorum sensing widely produced by gram-negative bacteria. Plants also produce and secrete compounds similar to AHLs, which affect bacterial quorum sensing. For example, plant-secreted natural N-acylethanolamines (NAEs) are similar to bacterial AHLs. In response to elicitors, N-acylethanolamines production is enhanced in leaves and gets accumulated in seeds that are desiccated. The application of alkamide, which is another bacterial AHL similar to signalling molecules and NAEs, to seedlings of Arabidopsis affects morphogenesis in a concentration-dependent way by altering the growth of root and shoot. Mutant Pseudomonas fluorescens 2P24 having the deletion of AHLs-encoding gene pcoI failed to colonize the rhizosphere of wheat, while pcoI complementation could successfully restore the wild-type activity. Systemic defence against Alternaria alternata fungi in tomato could be achieved through the enhanced synthesis of ethylene and salicylic acid by AHLs-secreting bacteria in soil (Ortiz-Castro et al. 2009). Two different but conserved homoserine-based quorum sensing systems were detected in PGPR Paraburkholderia sp., i.e. BpI.1/R.1 and BpI.2/R.2. BpI.1/R.1 has an important role in colonization for Arabidopsis thaliana. The present study indicates that BpI.1/R.1 quorum sensing system has a vital role in biofilm production control via regulation of expression of ecf26.1 gene, which is responsible for the encoding of sigma factor, having an extra cytoplasmic function (Zuniga et al. 2017).
by Genetically Engineered Filamentous Fungs
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
T. Vichitsoonthonkul, Y. W. Chu, H. S. Sodhi, G. Saunders
A potential cloning strategy related to genetic complementation involves loss or gain of genetic function in a wild-type background. The first part is based on the observation of Hynes et al. [18] that transcriptional regulators can be titrated away by introduction of multiple copies of sequences to which they bind. Titration of transcription factors often leads to a readily identifiable alteration in phenotype. Because vectors that allow selection for integration of multiple plasmid copies are available, for example, plasmids containing amdS or bleomycin-resistance genes, it should be possible to identify specific DNA sequences by their ability to titrate away regulatory factors. Genetic function can also be lost by the insertion of transforming DNA into a locus. Transformed strains can be examined for desired mutations that may have occurred as a result of plasmid insertion. Plasmids containing genomic sequences adjacent to the point of insertion can be recovered by digesting DNA with a restriction enzyme that cuts once within the plasmid, religating, and finally transforming E. coli cells.
Inorganic Chemical Pollutants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
They hypothesized that these two genes are key components of the bacterial Hg methylation pathway, with the putative corrinoid protein facilitating methyl transfer and the ferredoxin carrying out corrinoid reduction. Therefore, they deleted these genes individually, and also together, from D. desulfuricans ND132 (supplementary text). Additionally, they deleted the orthologs GSU1440 and GSU1441 together, and GSU1440 individually, from G. sulfurreducens PCA. In both of these organisms, CH3Hg+ production decreased in the deletion mutants by >99% relative to the parental strains. Complementation of the two-gene deletions by reincorporation of the genes into the chromosomes restored 26% and 87% of the wild-type methylation activity in D. desulfuricans ND132 and G. sulfurreducens PCA, respectively, as measured by inductively coupled plasma mass spectrometry (ICP-MS). Deletion of DND132_1057 alone yielded <0.2% of wild-type methylation activity, and subsequent complementation showed 97% methylation activity. Complementation of either gene alone into the double-deletion mutant did not restore detectable methylation activity (Figure 4.20). Restoration of ΔDND132_1056 was not performed. Although the relative location of the two genes is consistent with cotranscription, reverse transcription polymerase chain reaction confirmed the transcription of DND132_1056 in the ΔDND132_1057 strain and DND132_1057 in the ΔDND132_1056 mutant.
Assessment of natural variability in leaf morphological and physiological traits in maize inbreds and their related hybrids during early vegetative growth
Published in Egyptian Journal of Basic and Applied Sciences, 2019
Farag Ibraheem, Eman M. El-Ghareeb
The genetic, molecular, and physiological mechanisms of heterosis are not fully understood [24,25]. Genetically, two main hypotheses have been proposed to explain the genetic basis of heterosis. The dominance hypothesis attributes heterosis to the accumulation of growth and yield-favoring alleles and complementation of harmful recessive ones in maize hybrids. Over-dominance hypothesis refers heterosis to the superior action of heterozygosity of alleles at individual loci over homozygosity at the same loci [26,27]. Epistasis and other molecular mechanisms including epigenetic, differential gene expression in hybrids and inbreds, and siRNA have also been implicated in controlling heterosis [27–30]. Physiologically, heterosis has been attributed to alterations in enzyme activity, protein metabolism, energy use, mitochondrial metabolism, metabolic flux/balance, circadian clock functions, carbon fixation, phytohormonal level (particularly GA) and cell cycle progression in inbreds and hybrids [18,23,31].