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At least 829 records · Page 46

Mutation network-based understanding of pleiotropic and epistatic mutational behavior of Enterococcus faecalis FMN-dependent azoreductase

We previously identified a highly active homodimeric FMN-dependent NADH-preferred azoreductase (AzoA) from Enterococcus faecalis, which cleaves the azo bonds (R-N = N-R) of diverse azo dyes, and determined its crystal structure. The preliminary network-based mutational analysis suggested that the two residues, Arg-21 and Asn121, have an apparent mutational potential for fine-tuning of AzoA, based on their beneficial pleiotropic feedbacks. However, epistasis between the two promising mutational spots in AzoA has not been obtained in terms of substrate binding and azoreductase activity. In this study, we further quantified, visualized, and described the pleiotropic and/or epistatic behavior of six single or double mutations at the positions, Arg-21 and Asn-121, as a further research endeavor for beneficial fine-tuning of AzoA. Based on this network-based mutational analysis, we showed that pleiotropy and epistasis are common, sensitive, and complex mutational behaviors, depending mainly on the structural and functional responsibility and the physicochemical properties of the residue(s) in AzoA.

Rational design↗

Multigene engineering in plants: Technologies, applications, and future prospects

The emerging bioeconomy presents a promising solution to both economic and environmental challenges. Within the bioeconomy, plants serve as a renewable, sustainable, and cost-effective source of foods, fuels, chemicals, and materials. However, traditional breeding and single-gene engineering approaches fall short in addressing complex traits (e.g., drought tolerance, disease resistance, yield, nutrient use efficiency) which are controlled by multiple genes. The complexity of plant biology often necessitates the use of multigene engineering (MGE), which involves simultaneous ectopic expression, up/down-regulation, or editing of multiple genes, to enhance plant traits relevant to the bioeconomy. These genes may be associated with distinct traits or function as components of specific metabolic and regulatory pathways. This review summarizes current technologies for MGE within the synthetic biology-driven Design-Build-Test-Learn (DBTL) framework, detailing its four key stages: Design – gene construct development; Build – DNA assembly and plant transformation; Test – the molecular, biochemical, and physiological characterization of engineered plants; and Learn – computational modeling to refine, multiplex and iterate the process. Despite good progress in the applications of MGE in biofortification, metabolic engineering, and stress resilience, challenges remain in construct stability, coordinated gene expression, and regulatory predictability. We identified optimization paths and future directions to accelerate MGE deployment in sustainable agriculture, with possible societal benefits including reduced production costs, increased yield, and improved food and nutritional security.

AI-aided plant engineering↗

iMatTOUGH: An open-source Matlab-based graphical user interface for pre- and post-processing of TOUGH2 and iTOUGH2 models

TOUGH2 and iTOUGH2 are powerful models that simulate the heat and fluid flows in porous and fracture media, and perform parameter estimation, sensitivity analysis and uncertainty propagation analysis. However, setting up the input files is not only tedious, but error prone, and processing output files is time consuming. Here, we present an open source Matlab-based tool (iMatTOUGH) that supports the generation of all necessary inputs for both TOUGH2 and iTOUGH2 and visualize their outputs. The tool links the inputs of TOUGH2 and iTOUGH2, making sure the two input files are consistent. It supports the generation of rectangular computational mesh, i.e., it automatically generates the elements and connections as well as their properties as required by TOUGH2. The tool also allows the specification of initial and time-dependent boundary conditions for better subsurface heat and water flow simulations. The effectiveness of the tool is illustrated by an example that uses TOUGH2 and iTOUGH2 to estimate soil hydrological and thermal properties from soil temperature data and simulate the heat and water flows at the Rifle site in Colorado.

58 GEOSCIENCES↗

Calculation of two-dimension radial electric field in boundary plasmas by using BOUT++

The steady state radial electric field (Er) is measured by coupling a plasma transport model with the quasi-neutrality constraint and the vorticity equation within the BOUT++ framework. Due to the experimentally measured plasma density and temperature profiles in Alcator C-Mod discharges, the effective radial particle and heat diffusivities are inferred from the set of plasma transport equations. The effective diffusivities are then extended into the scrape-off layer (SOL) to calculate the plasma density, temperature and flow profiles across the separatrix into the SOL with the electrostatic sheath boundary conditions (SBC) applied on the divertor plates. Given these diffusivities, the electric field can be calculated self-consistently across the separatrix from the vorticity equation with SBC coupled to the plasma transport equations. The sheath boundary conditions act to generate a large and positive Er in the SOL, which is consistent with experimental measurements. The effect of magnetic particle drifts is shown to play a significant role on local particle transport and Er by inducing a net particle flow in both the edge and SOL regions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

RNA-Seq-based high-resolution linkage map reveals the genetic architecture of fruiting body development in shiitake mushroom, Lentinula edodes

Fruiting body development (FBD) of mushroom-forming fungi has attracted tremendous interest. However, the genetic and molecular basis of FBD is poorly known. Here, using Lentinula edodes (shiitake) as a model, we deciphered the genetic architecture underlying fruiting body-related traits (FBRTs) by combined genomic, genetic and phenotypic data. Using RNA-Seq of fruiting bodies from 110 dikaryons in a bi-parental mapping population, we constructed an ultra-high-density genetic map of L. edodes (Lemap2.0) with a total length of 810.14 cM, which covered 81.7% of the shiitake genome. A total of 94 scaffolds of the shiitake genome were aligned to Lemap2.0 and re-anchored into nine pseudochromosomes. Then via quantitative trait locus (QTL) analysis, we disclosed an outline of the genetic architecture of FBD in shiitake. Twenty-nine QTLs and three main genomic regions associated with FBD of shiitake were identified. Using meta-QTL analysis, seven pleiotropic QTLs for multiple traits were detected, which contributed to the correlations of FBRTs. In the mapped QTLs, the expression of 246 genes were found to significantly correlate with the phenotypic traits. Thirty-three of them were involved in FBD and could represent candidate genes controlling the shape and size of fruiting bodies. Collectively, our findings have advanced our understanding of the genetic regulation of FBD in shiitake and mushroom-forming fungi at large.

59 BASIC BIOLOGICAL SCIENCES↗

Plant myo -inositol transport influences bacterial colonization phenotypes

Plant microbiomes are assembled and modified through a complex milieu of biotic and abiotic factors. Despite dynamic and fluctuating contributing variables, specific host metabolites are consistently identified as important mediators of microbial interactions. We combine information from a large-scale metatranscriptomic dataset from natural poplar trees and experimental genetic manipulation assays in seedlings of the model plant Arabidopsis thaliana to converge on a conserved role for transport of the plant metabolite myo-inositol in mediating host-microbe interactions. While microbial catabolism of this compound has been linked to increased host colonization, we identify bacterial phenotypes that occur in both catabolism-dependent and -independent manners, suggesting that myo-inositol may additionally serve as a eukaryotic-derived signaling molecule to modulate microbial activities. Our data suggest host control of this compound and resulting microbial behavior are important mechanisms at play surrounding the host metabolite myo-inositol.

59 BASIC BIOLOGICAL SCIENCES↗

An orphan gene BOOSTER enhances photosynthetic efficiency and plant productivity

Organelle-to-nucleus DNA transfer is an ongoing process playing an important role in the evolution of eukaryotic life. Here, genome-wide association studies (GWAS) of non-photochemical quenching parameters in 743 Populus trichocarpa accessions identified a nuclear-encoded genomic region associated with variation in photosynthesis under fluctuating light. The identified gene, BOOSTER (BSTR), comprises three exons, two with apparent endophytic origin and the third containing a large fragment of plastid-encoded Rubisco large subunit. Higher expression of BSTR facilitated anterograde signaling between nucleus and plastid, which corresponded to enhanced expression of Rubisco, increased photosynthesis, and up to 35% greater plant height and 88% biomass in poplar accessions under field conditions. Overexpression of BSTR in Populus tremula × P. alba achieved up to a 200% in plant height. Similarly, Arabidopsis plants heterologously expressing BSTR gained up to 200% in biomass and up to 50% increase in seed.

60 APPLIED LIFE SCIENCES↗