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Xanthomonas is a well-studied genus of bacterial plant pathogens whose members cause a variety of diseases in economically important crops worldwide. Genomic and functional studies of these phytopathogens have provided significant understanding of microbial-host interactions, bacterial virulence and host adaptation mechanisms including microbial ecology and epidemiology. In addition, several strains of Xanthomonas are important as producers of the extracellular polysaccharide, xanthan, used in the food and pharmaceutical industries. This polymer has also been implicated in several phases of the bacterial disease cycle. In this review, we summarise the current knowledge on the infection strategies and regulatory networks controlling virulence and adaptation mechanisms from Xanthomonas species and discuss the novel opportunities that this body of work has provided for disease control and plant health. [ABSTRACT FROM AUTHOR]

Two-component regulatory system (TCS), a major type of cellular signal transduction system, is widely used by bacteria to adapt to different conditions and to colonize certain ecological niches in response to environmental stimuli. TCSs are of distinct functional diversity, genetic diversity, and species specificity (pathovar specificity, even strain specificity) across bacterial groups. Although TCSs have been demonstrated to be crucial to the virulence of Xanthomonas , only a few researches have been reported about the studies of TCSs in Xanthomonas oryzae pathovar oryzicola (hereafter Xoc), the pathogen of rice bacterial streak disease. In the genome of Xoc strain GX01, it has been annotated 110 TCSs genes encoding 54 response regulators (RRs), 36 orthodox histidine kinase (HKs) and 20 hybrid histidine kinase (HyHKs). To evaluate the involvement of TCSs in the stress adaptation and virulence of Xoc , we mutated 50 annotated RR genes in Xoc GX01 by homologous vector integration mutagenesis and assessed their phenotypes in given conditions and tested their virulence on host rice. 17 RR genes were identified to be likely involved in virulence of Xoc , of which 10 RR genes are novel virulence genes in Xanthomonas , including three novel virulence genes for bacteria. Of the novel candidate virulence genes, some of which may be involved in the general stress adaptation, exopolysaccharide production, extracellular protease secretion and swarming motility of Xoc. Our results will facilitate further studies on revealing the biological functions of TCS genes in this phytopathogenic bacterium. [ABSTRACT FROM AUTHOR]

Background and objectives: Increase in the world population is usually followed by a growing demand for food and increasingly higher requirements for the quality of food. The existing crops may require immediate improvement and optimization in order to adjust to market demands and the deteriorating environment. Findings: Genome-editing technology, a relatively advanced technology method that appeared in recent years, can accurately edit (i.e., insert, delete, or replace) genes and directionally modify crops by changing the plant's heredity and performance. Conclusions: Currently, some of the modern genome-editing approaches have been applied rather widely in crop breeding: for example, zinc finger nuclease, transcription activator-like effector nuclease, and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein. [ABSTRACT FROM AUTHOR]

An effective multiplex real-time polymerase chain reaction (PCR) assay for the simultaneous detection of three major pathogens, Nosema bombycis Nägeli (Microsporidia: Nosematidae), Bombyx mori nucleopolyhedrovirus (Baculoviridae: genus Alphabaculovirus) (NPV), and Bombyx mori densovirus (Parvoviridae: genus Iteravirus) (DNV), in silkworms (Bombyx mori (Linnaeus); Lepidoptera: Bombycidae) was developed in this study. Polymerase chain reaction and real-time PCR tests and basic local alignment search tool searches revealed that the primers and probes used in this study had high specificities for their target species. The ability of each primer/probe set to detect pure pathogen DNA was determined using a plasmid dilution panel, in which under optimal conditions the multiplex real-time PCR assay showed high efficiency in the detection of three mixed target plasmids with a detection limit of 8.5×103 copies for N. bombycis and Bombyx mori NPV (BmNPV) and 8.5×104 copies for Bombyx mori DNV (BmDNV). When the ability to detect these three pathogens was examined in artificially inoculated silkworms, our method presented a number of advantages over traditional microscopy, including specificity, sensitivity, and high-throughput capabilities. Under the optimal volume ratio for the three primer/probe sets (3:2:2=N. bombycis:BmNPV:BmDNV), the multiplex real-time PCR assay showed early detection of BmNPV and BmDNV by day 1 post inoculation using DNA templates of the three pathogens in various combinations from individually infected silkworms; the early detection of N. bombycis was possible by day 3 post inoculation using the DNA isolated from the midgut of N. bombycis-infected silkworms. [ABSTRACT FROM AUTHOR]

Location estimation of mobile target is an important research in wireless sensor networks. However, the phenomenon of non line of sight affects the accuracy of location estimating algorithms greatly. In order to improve the accuracy of location estimation of mobile targets, we proposed a game theory based location method algorithm in wireless sensor networks. In the proposed method, we first estimate the initial locations of mobile target with a support vector regression model, and then use game theory to smooth the already estimated locations. In the game model, game based filter and noise generator are two game rivals. The game filter aims to minimize the objective function of the game model, and the noise generator aims to maximize the same objective function. We propose a differential game theory based algorithm for solving the optimal resolution. The experiments show that, the proposed method is more powerful, and can be used to mobile target locating and tracking. [ABSTRACT FROM AUTHOR]

A number of species of bacteria from the genus B urkholderia have been shown to be causal agents of diseases of rice. These diseases, caused by B urkholderia glumae, B . gladioli and B . plantarii, are becoming increasingly common across the globe. This is particularly so for B . glumae, whose ability to grow at elevated temperatures suggests that it may become a prevalent problem in an era of global warming. Despite the increasing threat to rice, relatively little is known about the virulence mechanisms employed by these pathogens. Work over the last 5 years has provided an increasing insight into these factors and their control by environmental and other cues. In addition, the determination of a number of genome sequences has allowed bioinformatic predictions of further possible mechanisms, which can now be investigated experimentally. Here, we review recent advances in the understanding of virulence of B urkholderia to rice, to include discussion of the roles of toxins, type II secreted enzymes, type III secreted effectors and motility as well as their regulation by quorum sensing, two-component systems and cyclic di- GMP signalling. Finally, we consider a number of approaches for the control of bacterial virulence through the modulation of quorum sensing and toxin degradation. [ABSTRACT FROM AUTHOR]