Fontes de resistência múltipla à murcha de fusário em tomateiro

The objective of this work was to evaluate the reaction of 48 tomato (Solanum lycopersicum) accessions, including ones of wild species, to isolates of the three Fusarium oxysporum f. sp. lycopersici (FOL) races. Molecular markers in close linkage to I‑1, I‑2, and I‑3 resistance genes were used. The combination of bioassays and specific molecular markers showed high correlation levels for most accessions. Solanum peruvianum and S. corneliomuelleri accessions showed resistance to all FOL races; the introgression of resistance factors of these genotypes into elite tomato germplasm is of great significance to breeding programs.O objetivo deste trabalho foi avaliar a reação de 48 acessos de tomateiro (Solanum lycopersicum), inclusive de espécies selvagens, a diferentes isolados das três raças de Fusarium oxysporum f. sp. lycopersici (FOL). Utilizaram-se marcadores moleculares ligados aos genes de resistência I‑1, I‑2 e I‑3. A combinação de bioensaios e marcadores moleculares específicos mostrou elevada correlação para a maioria dos acessos. Acessos de S. peruvianum e S. corneliomuelleri apresentaram resistência contra todas as raças de FOL; a introgressão de fatores de resistência destes genótipos em germoplasma‑elite de tomateiro é de elevado interesse para o melhoramento genético desta cultura

Simultaneous detection of tomato resistance factors to Fusarium wilt in tomato by multiplex PCR

O objetivo deste trabalho foi elaborar e validar um protocolo de detecção simultânea, via reação em cadeia da polimerase multiplex (PCR multiplex), de regiões genômicas do tomateiro (Solanum lycopersicum) associadas a fatores de resistência às três raças fisiológicas de Fusarium oxysporum f. sp. lycopersici (FOL). Os pares de iniciadores empregados foram SSR‑67 (específico para o gene I‑1), TFusrr (específico para o gene I‑2) e SSRD (específico para o gene I‑3). Os resultados de genotipagem com marcadores moleculares foram comparados aos resultados de fenotipagem de uma coleção de germoplasma de tomateiro, em bioensaios de inoculação de isolados das três raças de FOL em plântulas, pelo método de imersão das raízes. A resistência ou a suscetibilidade foi confirmada por PCR, por meio de visualização dos âmplicons específicos para as regiões‑alvo ligadas aos fatores de resistência às distintas raças de FOL. O protocolo elaborado para o uso conjunto dos marcadores moleculares, em PCR multiplex, permite a seleção de acessos de tomateiro resistentes às raças 1, 2, e 3 de F. oxysporum f. sp. lycopersici de maneira similar à realizada com a utilização de cada um separadamente. O PCR multiplex representa uma ferramenta viável para monitorar a incorporação desses fatores de resistência em linhagens de tomateiro.The objective of this work was to develop and validate a protocol for simultaneous detection by multiplex polymerase chain reaction (multiplex PCR) of tomato (Solanum lycopersicum) genomic regions associated with factors of resistance to three physiological races of Fusarium oxysporum f. sp. lycopersici (FOL). The employed primer pairs were SSR‑67 (specific to the I‑1 gene), TFusrr (specific to the I‑2 gene), and SSRD (specific to the I‑3 gene). Genotyping results with molecular markers were compared with the phenotyping ones of a tomato germplasm collection, in bioassays of isolate inoculation of the three FOL races in seedlings by root dipping. The resistance or susceptibility was confirmed by PCR, through the visualization of specific amplicons corresponding to the target regions linked to the factors of resistance to distinct FOL races. The elaborated protocol for the joint use of the molecular markers, by multiplex PCR, allows of the selection of tomato accessions that are resistant to the races 1, 2, and 3 of F. oxysporum f. sp. lycopersici in a similar way to that done with each one separately. PCR multiplex is a viable tool to monitor the incorporation of these resistance factors into tomato inbred lines

Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Advanced Signal Processing Methods for Planetary Radar Sounders Data

Radar sounders are spaceborne electromagnetic sensors specifically designed for subsurface investigations. They operate in the HF/VHF part of the electromagnetic spectrum and are widely employed for applications such as monitoring changes to the polar ice sheets of the Earth and for the study of planetary bodies (e.g. Mars) from satellite. Radar sounding of planetary bodies is a relatively young discipline both in terms of system design and data processing architectures. As a result of the current state of the art in system design, the data recorded by radar sounders are typically affected by artifacts, such as off-nadir surface clutter, which hinders its interpretation by scientists. On top of that, the analysis of the very large of amount of data produced by such systems is typically performed manually by experts thus inherently subjective and time-consuming. Therefore the development of automatic high-level processing strategies for reliable, objective and fast extraction of information is needed. Accordingly, this thesis work deals with different aspects of radar sounding namely system design, low-level and high-level processing. The thesis provides three main novel contributions to the state of the art. First, we present a study on system design, performance assessment and 3D electromagnetic simulations of a radar sounding system specifically tailored for detecting lava tubes under the Moon surface. Lava tubes are considered to be important and useful structures. By having a stable temperature and by providing protection against cosmic ray radiation and micrometeorites impacts, they could potentially serve as natural shelter for human outposts on the Moon. The results presented in this thesis show that a multi-frequency radar sounder is the best option for effectively sound most of the lava tube dimension expected from the literature and that they show unique electromagnetic signature which can be used for their detection. The second novel contribution is focused on low-level processing and consists in a bio-inspired clutter detection model based on bats echolocation. Very relevant analogies occur between a bat and radar sounder such as the nadir acquisition geometry. The mathematical model proposed in this thesis adapts the bats frequency diversity strategy (i.e. multi-frequency approach) to solve clutter ambiguities to the radar sounding case. The proposed bio-inspired clutter detection model has been tested and validated on experimental data acquired over Mars. The experimental results showed that the method is able to discriminate in a precise way the radar echoes arising from subsurface targets with respect to off-nadir surface clutter ones. The third novel contribution of this thesis goes in the direction of high-level processing and in particular of automatic data analysis for accurate and fast extraction of relevant information from radar sounding data. To this extent, we propose a novel automatic method for retrieving the spatial position and radiometric properties of the subsurface layers based on Hidden Markov Models for radar response modeling and the Viterbi Algorithm for the inference step. Furthermore, a novel radargram enhancement and denoising technique has been developed to support the detection step. The effectiveness of the technique has been demonstrated on different radargrams acquired over the North Pole of Mars pointing out its superiority with respect to current state of the art techniques

A multi-frequency radar sounder for lava tubes detection on the Moon: Design, performance assessment and simulations

Lunar lava tubes have attracted special interest as they would be suitable shelters for future human outposts on the Moon. Recent experimental results from optical images and gravitational anomalies have brought strong evidence of their existence, but such investigative means have very limited potential for global mapping of lava tubes. In this paper, we investigate the design requirement and feasibility of a radar sounder system specifically conceived for detecting subsurface Moon lava tubes from orbit. This is done by conducting a complete performance assessment and by simulating the electromagnetic signatures of lava tubes using a coherent 3D simulator. The results show that radar sounding of lava tubes is feasible with good performance margins in terms of signal-to-noise and signal-to-clutter ratio, and that a dual-frequency radar sounder would be able to detect the majority of lunar lava tubes based on their potential dimension with some limitations for very small lava tubes having width smaller than 250 m. The electromagnetic simulations show that lava tubes display an unique signature characterized by a signal phase inversion on the roof echo. The analysis is provided for different acquisition geometries with respect to the position of the sounded lava tube. This analysis confirms that orbiting multi-frequency radar sounder can detect and map in a reliable and unambiguous way the majority of Moon lav

Distributed Radar Sounder: A Novel Concept for Subsurface Investigations Using Sensors in Formation Flight

Spaceborne radar sounders are nadir-looking sensors operating in the high frequency (HF) or very high frequency (VHF) bands with subsurface sensing capabilities. Due to technological limitations, this type of sensors often deploys omnidirectional antennas. This results in undesired artifacts such as off-nadir clutter which could hinder data interpretation. Very recent technological advancements open up the possibility of synthesizing very large antenna apertures in HF/VHF band by using small satellites array deployed in suitable orbital formation flying. Accordingly, in this study, we propose a novel concept of distributed radar sounder system. The proposed concept is complemented with a mathematical model for performance prediction which takes into account the uncertainty on the position of the sensors. Moreover, we discuss possible orbital solutions for the problem of the deployment of the distributed radar sounder system. The results show that a distributed radar sounder operating in small satellites formation flying is particularly appealing as it can: 1) substantially reduce the impact of surface clutter; 2) increase the across-track resolution; 3) increase the signal-to-noise ratio (SNR) (or, alternatively, decrease the overall required transmitted power with respect to a traditional single configuration radar sounder design); and 4) provide large flexibility in the data processing of the signals acquired by the different sensors

An Unsupervised Fuzzy System for the Automatic Detection of Candidate Lava Tubes in Radar Sounder Data

Lava tubes are buried channels that transport thermally insulated lava. Nowadays, lava tubes on the Moon are believed to be empty and thus indicated as potential habitats for humankind. In recent years, several studies investigated possible lava tube locations, considering the gravity anomaly distribution and surficial volcanic features. This article proposes a novel and unsupervised method to map candidate buried empty lava tubes in radar sounder data (radargrams) and extract their physical properties. The approach relies on a model that describes the geometrical and electromagnetic (EM) properties of lava tubes in radargrams. According to this model, reflections in radargrams are automatically detected and analyzed with a fuzzy system to identify those associated with lava tube boundaries and reject the others. The fuzzy rules consider the EM and geometrical properties of lava tubes, and thus, their appearance in radargrams. The proposed method can address the complex task of identifying candidate lava tubes on a large number of radargrams in an automatic, fast, and objective way. The final decision on candidate lava tubes should be taken in postprocessing by expert planetologists. The proposed method is tested on both a real and a simulated data set of radargrams acquired on the Moon by the Lunar Radar Sounder (LRS). Identified candidate lava tubes are processed to extract geometrical parameters, such as the depth and the thickness of the crust (roof)