High colonization by native arbuscular mycorrhizal fungi (AMF) of rubber trees in small-holder plantations on low fertility soils in North East Thailand

Rubber tree is a very important crop in Thailand, representing an essential source of income for farmers. In the past two decades, rubber tree plantations have been greatly expanding in unfavorable areas, where climate conditions are difficult and soil fertility is very poor. To optimize latex yields, mineral fertilizers have been widely used. A better understanding of the roles of the biological compartment in soil fertility is essential to determine alternative management practices to sustain soil fertility and optimize latex yields. Arbuscular mycorrhizal fungi (AMF) are widely recognized as beneficial for plants, mainly through their role in improving plant nutrient uptake. The objective of this study was to assess the AMF populations in rubber tree plantations and the impact of both soil characteristics and plantation age on these communities. Our results showed that all rubber trees were highly colonized, regardless of the soil structure and nutrient contents. AMF colonization was not affected by the age of the trees, suggesting that maintaining the symbiosis is likely to be beneficial at all stages. A better understanding and management of the microbial communities would contribute to maintaining or restoring soil fertility, leading to a better tree growth and optimized latex yield.

Identification and topographical characterisation of microbial nanowires in Nostoc punctiforme

Extracellular pili-like structures (PLS) produced by cyanobacteria have been poorly explored. We have done detailed topographical and electrical characterisation of PLS in Nostoc punctiforme PCC 73120 using transmission electron microscopy (TEM) and conductive atomic force microscopy (CAFM). TEM analysis showed that N. punctiforme produces two separate types of PLS differing in their length and diameter. The first type of PLS are 6-7.5 nm in diameter and 0.5-2 µm in length (short/thin PLS) while the second type of PLS are ~20-40 nm in diameter and more than 10 µm long (long/thick PLS). This is the first study to report long/thick PLS in N. punctiforme. Electrical characterisation of these two different PLS by CAFM showed that both are electrically conductive and can act as microbial nanowires. This is the first report to show two distinct PLS and also identifies microbial nanowires in N. punctiforme. This study paves the way for more detailed investigation of N. punctiforme nanowires and their potential role in cell physiology and symbiosis with plants.

Buckwheat as a Cover Crop in Florida: Mycorrhizal Status, Soil Analysis, and Economic Assessment

This thesis analyses buckwheat as a cover crop in Florida. The study was designed to demonstrate: soil enrichment with nutrients, mycorrhizal arbuscular fungi interactions, growth in different soil types, temperature limitations in Florida, and economic benefits for farmers. Buckwheat was planted at the FIU organic garden (Miami, FL) in early November and harvested in middle December. After incorporation of buckwheat residues, soil analyses indicated the ability of buckwheat to enrich soil with major nutrients, in particular, phosphorus. Symbiosis with arbuscular mycorrhizal fungi increased inorganic phosphorus uptake and plant growth. Regression analysis on aboveground buckwheat biomass weight and soil characteristics showed that high soil pH was the major limiting factor that affected buckwheat growth. Spatial analysis illustrated that buckwheat could be planted in South Florida throughout the year but might not be planted in North and Central Florida in winter. An economic assessment proved buckwheat to be a profitable cover crop.

The Effects of Arbuscular Mycorrhizal Fungi on four Legume Hosts in South Florida Pine Rockland Soils

This study addressed the effects of salinity and pot size on the interaction between leguminous plant hosts and arbuscular mycorrhizal fungi in four pine rockland soils using a shade house trap-plant experiment. Little is known about the belowground diversity of pine rocklands and the interactions between aboveground and belowground biota – an increased understanding of these interactions could lead to improved land management decisions, conservation and restoration efforts. Following twelve weeks of growth, plants were measured for root and shoot dry biomass and percent colonization by arbuscular mycorrhizal fungi. Overall, arbuscular mycorrhizal fungi had positive fitness effects on the four legume species (Cajanus cajan, Chamaecrista fasciculata, Tephrosia angustissima and Abrus precatorius), improving their growth rate, shoot and root biomass; pot size influenced plant-fungal interactions; and percent colonization by arbuscular mycorrhizal fungi was influenced by soil type as well as salinity.

The Sinorhizobium meliloti EmrR Regulator Is Required for Efficient Colonization of Medicago sativa Root Nodules

The nitrogen-fixing bacterium Sinorhizobium meliloti must adapt to diverse conditions encountered during its symbiosis with leguminous plants. We characterized a new symbiotically relevant gene, emrR (SMc03169), whose product belongs to the TetR family of repressors and is divergently transcribed from emrAB genes encoding a putative major facilitator superfamily-type efflux pump. An emrR deletion mutant produced more succinoglycan, displayed increased cell-wall permeability, and exhibited higher tolerance to heat shock. It also showed lower tolerance to acidic conditions, a reduced production of siderophores, and lower motility and biofilm formation. The simultaneous deletion of emrA and emrR genes restored the mentioned traits to the wild-type phenotype, except for survival under heat shock, which was lower than that displayed by the wild-type strain. Furthermore, the ΔemrR mutant as well as the double ΔemrAR mutant was impaired in symbiosis with Medicago sativa; it formed fewer nodules and competed poorly with the wild-type strain for nodule colonization. Expression profiling of the ΔemrR mutant showed decreased expression of genes involved in Nod-factor and rhizobactin biosynthesis and in stress responses. Expression of genes directing the biosynthesis of succinoglycan and other polysaccharides were increased. EmrR may therefore be involved in a regulatory network targeting membrane and cell wall modifications in preparation for colonization of root hairs during symbiosis.

Imaging identity: media, memory and portraiture in the digital age

Imaging Identity presents potent reflections on the human condition through the prism of portraiture. Taking digital imaging technologies and the dynamic and precarious dimensions of contemporary identity as critical reference points, these essays consider why portraits continue to have such galvanising appeal and perform fundamental work across so many social settings. This multidisciplinary enquiry brings together artists, art historians, art theorists and anthropologists working with a variety of media. Authors look beyond conventional ideas of the portrait to the wider cultural contexts, governmental practices and intimate experiences that shape relationships between persons and pictures. Their shared purpose centres on a commitment to understanding the power of images to draw people into their worlds. Imaging Identity tracks a fundamental symbiosis — to grapple with the workings of images is to understand something vital of what it is to be human.

Repensar=Reutilizar. o abandono como oportunidade. Fábrica Robinson: o instante na construção de um tempo provisório

Esta investigação procura mostrar/problematizar programas que questionem a reutilização de lugares, através de uma proposta de projeto provisório de arquitetura, no panorama do Património Industrial, num processo de revitalização. O intuito é procurar modelos/ações que possam responder às transformações, partindo do problema do abandono, dos espaços pós-industriais. O objetivo principal consiste em criar um processo de aproximação à problemática da reutilização cujo processo de elaboração de projeto encontra nas suas formas de produção e operação um discurso que faz a síntese entre prática artística, posição curatorial e arquitetura, na elaboração de um programa para um lugar revitalizando-o. O objeto deste estudo faz parte de uma investigação de pesquisa por projeto e encontra lugar no conjunto arquitetónico da Fábrica Robinson, em Portalegre, cuja apropriação inicial de parte do Convento de S. Francisco dá hoje lugar ao Espaço Robinson. O reconhecimento deste conjunto, como lugar de encontro entre um passado recente e um futuro pendente, marcou a proposta projetual. Proposta de projeto temporário cujo conceito estabelece a viabilidade de apropriação como forma de atuação provisória, subjacente ao ato de reutilizar, criando novos programas de ocupação, promovendo novas ideias e definições de património e assim devolvendo o significado às estruturas industriais vazias. O que preservar e como conservar pode demarcar a importância de salvaguarda deste património e a previsão da sua transmissão para o futuro, fixada pela ideia de preservação. A Fábrica Robinson e a revitalização urbana deste espaço configura, hoje, uma nova oportunidade para estes conjuntos arquitetónicos, e a importância da sua salvaguarda, na valorização do Património Industrial. O trabalho pretende demonstrar a ordem de relação entre programa e lugar no debate interdisciplinar e a hipótese de concretização projetual que preencha um vazio temporalmente suspenso; ABSTRACT: Rethinking = Reuse: The abandonment as opportunity Robinson Factory: The instant in the construction of a provisory time This research aims to show architectural programs that question the reuse of places in the context of industrial heritage, through an architectural design, in a revitalization process. The aim is to look to models / actions that, starting with the abandonment problem, may answer to the post-industrial spaces transformations. The main goal is to create an approximation process to the problem of reuse, whose project design process finds in its production and operations forms a symbiosis between artistic practice, curatioral approach and architecture, in the development of a program to revitalize a place. The object of this study is part of a research project / research by design concerning the architectural complex Fábrica Robinson located in Portalegre, whose original appropriation of part of Convento de S. Francisco is today occupied by Espaço Robinson. The acknowledgment of this complex as a space placed in-between a recent past and a pending future marked the design proposed. A temporary design proposal whose concept establishes the validity of the temporary action, underlying to the act of reuse, creating new occupation programs, promoting new ideas and heritage definitions and thus given back meaning to the empry industrial structures. What to preserve and how to save may mark the importance of safeguarding this heritage and the prediction of its transmission to the future, set by the idea of preservation. The Fábrica Robinson and the urban regeneration of this area sets itself as a new opportunity to safeguard these architectural ensembles and enhance the value of the industrial heritage. This study intend to show the relationship between the program and a vacant place, through a temporary proposal, supported by the interdisciplinary debate and the hypothesis of design implementation that completes a void temporarily suspended.

Global transcriptional response to salt shock of the plant microsymbiont Mesorhizobium loti MAFF303099

Soil salinity affects rhizobia both as free-living bacteria and in symbiosis with the host. The aim of this study was to examine the transcriptional response of the Lotus microsymbiont Mesorhizobium loti MAFF303099 to salt shock. Changes in the transcriptome of bacterial cells subjected to a salt shock of 10% NaCl for 30 min were analyzed. From a total of 7231 protein-coding genes, 385 were found to be differentially expressed upon salt shock, among which 272 were overexpressed. Although a large number of overexpressed genes encode hypothetical proteins, the two most frequently represented COG categories are "defense mechanisms" and "nucleotide transport and metabolism". A significant number of transcriptional regulators and ABC transporters genes were upregulated. Chemotaxis and motility genes were not differentially expressed. Moreover, most genes previously reported to be involved in salt tolerance were not differentially expressed. The transcriptional response to salt shock of a rhizobium with low ability to grow under salinity conditions, but enduring a salinity shock, may enlighten us concerning salinity stress response mechanisms.

Agronomic efficiency of Bradyrhizobium in peanut under different environments in Brazilian Northeast.

Several legumes have natural ability to associate with nitrogen - fixing bacteria known as rhizobia. The efficiency of this association depends on the plant and bacterial genotype and the edaphoclimatic conditions. Peanut is a tropical legume able to associate with a wide range of rhizobia and the selection of efficient bacteria is important to increase the nitrogen fixation in this crop. In order to investigate the agronomic efficiency of two Bradyrhizobiumstrains, two peanut genotypes were used in field trails carried out in three environments located at Brazilian Northeast. The genotypes (BR1 and L7 Bege) were submitted to rhizobial inoculation (SEMIA 6144 or ESA 123, both Bradyrhizobium strains, and chemical nitrogen fertilization in randomized block design experiments. The following traits were analyzed: flowering (F), main axis height (MAH), number of nodules/plant (NN), number of pods/plant (NP) and weight of pods (WP). Differential responses were found in all to treatments to NN, NP and WP, in the three environments studied. Overall, ESA 123 showed good agronomic performance inducing higher pod production. The results supportthe evaluation of the Bradyrhizobium in further experiments aiming at its recommendation to commercial inoculants in Brazilian Northeast region.