Plant pathogen interactions have been an area of increased interest in the scientific community. This is mainly because of the amount of global waste that occurs each year due to pathogens destroying crops. Plant pathogen interactions have been coined as an “arms race” with the plant and pathogens constantly trying to out compete the other and evolving new mechanisms in order to ensure survival. An example of this is the relationship between Ustilago maydis and the maize plant. U.maydis is a fungus that causes tumor growths called smut on infected maize plants by establishing a biotrophic relationship. A biotrophic relationship means that the pathogen requires living host tissue in order to grow and survive, often infecting the plant in a way that involves evading or suppressing the host immune system (effectors as tools in disease resistance). The fungus has recently become the focus of a lot of scientific interest however; this interest is not because it causes devastating loss of crops or money but because of its ease of being grown in a lab, up until the stage of appressoria development. In 2006 its genome sequence was made available which increases its convenience for genetic studies. The availability of the genome revealed that U.maydis shares more similarities with humans then budding yeast does and therefore is a more appropriate candidate when exploring areas such as homologous recombination, mitosis and microtubule organization (the top 10 fungal pathogens in molecular plant pathology).
When it comes to plant pathogen interactions the question of how the pathogen manages to evade the host immune system or manipulate the host metabolism for its benefit has been of upmost interest. The term, effector molecule, came to ...
... middle of paper ...
...cover what metabolic or genetic changes they may have on the host plant. Research would also need to focus on whether the action of these effector molecules is relevant just to U.maydis or whether they are found in other smut fungi, other biotrophic fungi, other fungi in general, or other plant pathogens and whether the action of the effector molecules differs depending on the host that is being infected. These questions could be answered through the help of comparative genomics however in vivo studies would also be needed to establish whether the effects of conserved sequence motifs of effector molecules in the pathogen have the same effects on different plants. Therefore there is still a long way to go in completely understanding all of the mechanisms employed not only by U.maydis in establishing infection but also other smut producing fungi and fungi in general.
Serratia marcescens, a Gram-negative bacillus, was originally and solely considered a biological marker in the medicinal industry, due to its highly natural red pigment: Prodigiosin (Hejazi and Falkiner, 1997). The pigment has numerous roles within bacteria, which can be further translated into the pharmaceutical and medical domain. This bacterium naturally occurs in water, soil, on plants as well as in humans and animals (Khanafari et al, 2006), where it is deemed an opportunistic pathogen.
After a series of biochemical tests and evaluation to determine several unknown bacteria, the bacterium Yersinia pestis was chosen to report. The discovery of Y. pestis dates back to 1894 by French/Swiss physician and bacteriologist named Alexandre Yersin. The name Yersinia pestis is synonymous with its more common name, the plague. Y. pestis is known to infect small rodents such as mice and rats, but is transmitted to humans through the bite of an infected animal or flea. Although this bacterium is known to still cause illness today, it is infamous for three pandemics that occurred in earlier centuries. According to the Centers for Disease Control and Prevention, the first recorded pandemic occurred in 541 A.D. and is known as the Justinian Plague. The second pandemic originated in China in 1334 and has received the egregious name the “Black Death.” Finally, the third outbreak took place in the 1860’s and is known as the Modern Plague. It wasn’t until the end of the Modern Plague that scientists discovered the causative agent and mode of transmission of the Yersinia pestis bacterium.
Thomas R. Warne, Leslie G. Hickok and Rodney J. Scott. (1988). Botanical Journal of the Linnean Society. Characterization and genetic analysis of antheridiogen-insensitive mutants in the fern Ceratopteris. 96 (1), 371-379.
In the 1880's a harmful fungus known as blight, inhabited the United States from imported Japanese chestnut trees. Blight quickly spread, killing chestnuts and chinquapins, which is another species of chestnut that produces 1 nut per bur. In 1904, Chestnut blight appeared infecting trees in New York City and spread at a rate of 20-50 miles per year. By 1906, W.A. Murrill reported that this disease is known to occur in New Jersey, Maryland, District of Columbia, and Virginia. In 1912, the Planet Quarantine Act was passed to reduce the chances of plant deterioration or devastation prevention. Chestnut Blight or Chestnut Bark Disease was originally found in 1904 and within 50 years, it spread across the eastern United States, from Maine to Georgia and as far west as the edge of Michigan. By 1950, the American chestnut was essentially eliminated as a forest tree. In 1972, importation from Italy gave a biological control in which a virus helped prevent the blight f...
Disease and parasitism play a pervasive role in all life. Many of these diseases start with microparasites, which are characterized by their ability to reproduce directly within an individual host. They are also characterized by their small size, short duration of infection, and the production of an immune response in infected and recovered individuals. Microparasites which damage hosts in the course of their association are recognized as pathogens. The level of the interaction and the extent of the resultant damage depends on both the virulence of the pathogen, as well as the host defenses. If the pathogen can overcome the host defenses, the host will be damaged and may not survive. If on the other hand the host defenses overcome the pathogen, the microparasite may fail to establish itself within the host and die.
Several potato plants carry resistance genes against PVX. Up to date two resistance genes have been identified. One gene product mediates salicylic acid systemic defense responses, whereas the other encodes the Rx protein. This protein has a nucleotide binding-site (NBS) and a leucine-rich repeat (LRR). The native fold of Rx confers an inactive conformation. Upon interactions with the viral CP, Rx partially unfolds, thereby its NBS-LRR domain [27]. This activates the signaling cascade mediating virus resistance.
Changes in factors such as temperature and rainfall, which can affect the growth of the fungus in the environment and how much of it is circulating in the air.
3: PUBMED Agrobacterium-Mediated Transformation of Tomato with rolB Gene Results in Enhancement of Fruit Quality and Foliar Resistance against Fungal Pathogens
Schumann, Gail L., and Cleora J. D'Arcy. Hungry Planet: Stories of Plant Diseases. St. Paul: American Phytopathological Society, 2012. Print.
Sordaria fimicola is a species of microscopic fungus that is an Ascomycete and are used to test for genetic variation in the lab setting (Sordaria fimicola: A Fungus used in Genetics, Volk). These organisms are what are called model organisms, or species that has been widely studied usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages (Sordaria fimicola, Volk). S. fimicola, because it is in the Ascomycota phylum, have a distinguishing reproductive structure called the ascus, which is surrounded by the perithecium. This cylindrical sac-like structure houses 8 haploid spores; created through meiosis to produce 4 haploid spores and then mitosis to make 8 (Lab Manual, pg. 59-68). Based on the genotype they will vary in order and color. There are 3 different ratios that can arise from the 8 ascospores: 4:4, 2:2:2:2, and 2:4:2 (black/wild type and tan coloration). The 4:4 ratio suggests that no crossing over had occurred because there is no difference in order of the color parents that were mated. The two other ratios suggest genetic recombination, or crossing over, because of the
The potato famine of 1846 was one of the biggest natural disasters in Irish history. The “explosive disease” said William Fry, Ph.D., caused by Phytophtera infestans, is a condition that prevents growth and destroys the plant by disease. P. infestans is a fungus-like pathogen that infects and destroys the leaves, stems, potato seed and the potato itself, turning it black and slimy (Craig, 1998). The first signs of blight are when leaves get brown specks on them that start to get white, hairy growth around them (Damsker, n.d.). In addition, leaves and stems withered very quickly. This if followed by a terrible smell. It spreads as a spore and grows rapidly in moist, warm and humid conditions. Today, the blight disease still affects potato crops. However, an application of the plant fungicide, metalaxyl, or copper sulfate mixtures and pesticide will prevent and eliminate or, at least, decrease the possibility of its appearance (Daly, 1996). In fact, according to Gibbon’s article in 2013, the pathogen and its host of dried leaves ar...
Sordaria fimicola belongs to the kingdom of fungi and is part of the phylum Ascosmycota. This fungus habitat is in the feces of herbivores. As many fungi Sordaria have one life cycles which is haploid/ diploid. It is commonly exits as a haploid organism, but when the mycelium from two individuals meets, the result is a diploid zygote. This diploid zygote which undergoes meiosis forms eight haploid ascospores . The ability of Sordaria to make 8 haploid ascospores is what makes it unique and important for the laboratory exercise done in lab.
Plant defences are those mechanisms employed by plants in response to herbivory and parasitism. According to Hanley et al. (2007), “the tissues of virtually all terrestrial, freshwater, and marine plants have qualities that to some degree reduce herbivory, including low nitrogen concentration, low moisture content, toxins or digestibility-reducing compounds”. The type of chemical defence may be species specific (Scott 2008). The defences that plants possess may be in the form of chemical production or in the form of physical defences such as thorns or spikes and even through reinforced, rigid leaves. “The compounds that are produced in response to herbivory can either have a direct effect on the attacker itself (e.g. toxins or digestibility reducers), or serve as indirect defenses by attracting the natural enemies of the herbivores” (Bezemer & van Dam 2005). This essay will focus on chemical plant defences and in particular the effects of terpenes, phenolics, nitrogen-based defences as well as allelopathy in plants.
It is estimated that over one-half of the antibiotics in the U.S. are used in food animal production. The overuse of antimicrobials in food animal production is an under-appreciated problem. In both human and veterinary medicine, the risk of developing resistance rises each time bacteria are exposed to antimicrobials. Resistance opens the door to treatment failure for even the most common pathogens and leads to an increasing number of infections. The mounting evidence of the relationship between antimicrobial use in animal husbandry and the increase in bacterial resistance in humans has prompted several reviews of agricultural practices by scientific authorities in a number of countries, including the US.
There are 5 main pathways of environmental transmission of pathogens. Those are air-borne, food-borne, water-borne, vector-borne and blood-borne. Air-borne transmission refers to any disease that is caused by a pathogen and transmitted through the air. These pathogens can be spread by coughing, sneezing, stirring dust, liquid spraying, or generally any activity that generate aerosol particles or droplets. These pathogens can include viruses, bacteria, or fungi. Some common examples of pathogens that are spread via air-borne transmission are rhinovirus, hantavirus, adenovirus, and influenza, among many others (cdc.gov).