The maize α-zein promoter can be utilized as a strong inducer of cellulase enzyme expression in maize kernels

Transgenic Research - Expression of recombinant proteins in plants is a technology for producing vaccines, pharmaceuticals and industrial enzymes. For the past several years, we have produced...     

TT2019 meeting report on the 15th Transgenic Technology Meeting in Kobe,Japan

Transgenic Research -     

Controlling chronic Pseudomonas aeruginosa infections by strategically interfering with the sensory function of SagS

The hybrid sensor SagS plays a central role in the formation of Pseudomonas aeruginosa biofilms, by enabling the switch from the planktonic to the biofilm mode of growth and by facilitating the transition of biofilm cells to a highly tolerant state. In this study, we examined the importance of the SagS key amino acid residues associated with biofilm formation (L154) and antibiotic tolerance (D105) in P. aeruginosa virulence. Recombinant P. aeruginosa ΔsagS and ΔsagS chromosomally expressing wild‐type sagS, or its two variants D105A and L154A, were tested for their potential to form biofilms and cause virulence in plants and mouse models of acute and chronic pneumonia. Although mutation of sagS did not alter P. aeruginosa virulence during acute infections, a significant difference in pathogenicity of sagS mutants was observed during chronic infections, with the L154A variant showing reduced bacterial loads in the chronic pneumonia model, while interference with the D105 residue enhanced the susceptibility of P. aeruginosa biofilms during tobramycin treatment. Our findings suggest that interference with the biofilm or tolerance regulatory circuits of SagS affects P. aeruginosa pathogenicity in chronic but not acute infections, and reveal SagS to be a promising new target to treat P. aeruginosa biofilm infections.     

FERONIA mutation induces high levels of chloroplast‐localized Arabidopsides which are involved in root growth

The FERONIA (FER) signaling pathway is known to have diverse roles in Arabidopsis thaliana, such as growth, reproduction, and defense, but how this receptor kinase is involved in various biological processes is not well established. In this work, we applied multiple mass spectrometry techniques to identify metabolites involved in the FER signaling pathway and to understand their biological roles. A direct infusion Fourier transform ion cyclotron resonance (FT‐ICR)‐MS approach was used for initial screening of wild‐type and feronia (fer) mutant plant extracts, and Arabidopsides were found to be significantly enriched in the mutant. As Arabidopsides are known to be induced by wounding, further experiments on wounded and non‐wounded leaf samples were carried out to investigate these oxylipins as well as related phytohormones using a quadrupole‐time‐of‐flight (Q‐TOF) MS by direct injection and LC‐MS/MS. In a root growth bioassay with Arabidopside A isolated from fer mutants, the wild‐type showed significant root growth inhibition compared with the fer mutant. Our results therefore implicated Arabidopsides, and Arabidopside A specifically, in FER functions and/or signaling. Finally, matrix‐assisted laser desorption/ionization MS imaging (MALDI‐MSI) was used to visualize the localization of Arabidopsides, and we confirmed that Arabidopsides are highly abundant at wounding sites in both wild‐type and fer mutant leaves. More significantly, five micron high‐spatial resolution MALDI‐MSI revealed that Arabidopsides are localized to the chloroplasts where many stress signaling molecules are made.     

Invasive plants negatively impact native,but not exotic,animals

Despite our growing understanding of the impacts of invasive plants on ecosystem structure and function, important gaps remain, including whether native and exotic species respond differently to plant invasion. This would elucidate basic ecological interactions and inform management. We performed a meta‐analytic review of the effects of invasive plants on native and exotic resident animals. We found that invasive plants reduced the abundance of native, but not exotic, animals. This varied by animal phyla, with invasive plants reducing the abundance of native annelids and chordates, but not mollusks or arthropods. We found dissimilar impacts among “wet” and “dry” ecosystems, but not among animal trophic levels. Additionally, the impact of invasive plants increased over time, but this did not vary with animal nativity. Our review found that no studies considered resident nativity differences, and most did not identify animals to species. We call for more rigorous studies of invaded community impacts across taxa, and most importantly, explicit consideration of resident biogeographic origin. We provide an important first insight into how native and exotic species respond differently to invasion, the consequences of which may facilitate cascading trophic disruptions further exacerbating global change consequences to ecosystem structure and function.     

The influence of ecological and life history factors on ectothermic temperature–size responses: Analysis of three Lycaenidae butterflies (Lepidoptera)

Body size has been shown to decrease with increasing temperature in many species, prompting the suggestion that it is a universal ecological response. However, species with complex life cycles, such as holometabolous insects, may have correspondingly complicated temperature–size responses. Recent research suggests that life history and ecological traits may be important for determining the direction and strength of temperature–size responses. Yet, these factors are rarely included in analyses. Here, we aim to determine whether the size of the bivoltine butterfly, Polyommatus bellargus, and the univoltine butterflies, Plebejus argus and Polyommatus coridon, change in response to temperature and whether these responses differ between the sexes, and for P. bellargus, between generations. Forewing length was measured using digital specimens from the Natural History Museum, London (NHM), from one locality in the UK per species. The data were initially compared to annual and seasonal temperature values, without consideration of life history factors. Sex and generation of the individuals and mean monthly temperatures, which cover the growing period for each species, were then included in analyses. When compared to annual or seasonal temperatures only, size was not related to temperature for P. bellargus and P. argus, but there was a negative relationship between size and temperature for P. coridon. When sex, generation, and monthly temperatures were included, male adult size decreased as temperature increased in the early larval stages, and increased as temperature increased during the late larval stages. Results were similar but less consistent for females, while second generation P. bellargus showed no temperature–size response. In P. coridon, size decreased as temperature increased during the pupal stage. These results highlight the importance of including life history factors, sex, and monthly temperature data when studying temperature–size responses for species with complex life cycles.     

Strong phenotypic divergence in spite of low genetic structure in the endemic Mangrove Warbler subspecies (Setophaga petechia xanthotera) of Costa Rica

Despite the enormous advances in genetics, links between phenotypes and genotypes have been made for only a few nonmodel organisms. However, such links can be essential to understand mechanisms of ecological speciation. The Costa Rican endemic Mangrove Warbler subspecies provides an excellent subject to study differentiation with gene flow, as it is distributed along a strong precipitation gradient on the Pacific coast with no strong geographic barriers to isolate populations. Mangrove Warbler populations could be subject to divergent selection driven by precipitation, which influences soil salinity levels, which in turn influences forest structure and food resources. We used single nucleotide polymorphisms (SNPs) and morphological traits to examine the balance between neutral genetic and phenotypic divergence to determine whether selection has acted on traits and genes with functions related to specific environmental variables. We present evidence showing: (a) associations between environmental variables and SNPs, identifying candidate genes related to bill morphology (BMP) and osmoregulation, (b) absence of population genetic structure in neutrally evolving markers, (c) divergence in bill size across the precipitation gradient, and (d) strong phenotypic differentiation (P_ST) which largely exceeds neutral genetic differentiation (F_ST) in bill size. Our results indicate an important role for salinity, forest structure, and resource availability in maintaining phenotypic divergence of Mangrove Warblers through natural selection. Our findings add to the growing body of literature identifying the processes involved in phenotypic differentiation along environmental gradients in the face of gene flow.