Plants like many eukaryotic composed organisms have the ability to detect and protect themselves against microorganisms known as pathogens. Plant fossils have recorded that land plant’s existence was established 480 million years ago, but molecularly, plant evolution began 700 million years ago. Molecular interaction with microbes and other organisms gave the shape and structure of plants, giving us an idea that microbes also evolve according to its host. Plants lack mobility depriving themselves from a somatic secondary immune response like many mammals giving pathogens the ability to easily attack. Pathogenic microbes can access plants by penetrating through the leaves, entering through plant wounds, or by using the stomata a natural pore on plants that opens and closes for gas exchange. To detect and stop from extensive damage from microbes, plants developed an immune system through its structure, chemicals, and defense proteins. Plants have …show more content…
NB-LRRs inhibit pathogen growth through a programmed cell death at the site of infection known as hypersensitive response (HR). The activation of NB-LRR activates metcaspase-1 proteins through MAP Kinases which alter the chloroplast. The chloroplast has the main role in activating HR in plants. It expresses reactive oxygen species (ROS) and reactive nitrogen oxide intermediates (NOI) defense signal molecules, including salicylic acid (SA) and jasmonic acid (JA) which are defense hormones used to activate HR. The production of ROS and a rapid ion reflux across the plasma membrane causes an uptake of calcium oxidizing NADPH. The alteration of calcium levels in the cell causes chloroplast disruption, chromatin condensation, swelling of the mitochondria and vacuoles, and shrinkage of the cytoplasm. The dead cells were the infected ones inhibiting pathogen growth to save the rest of the
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.
Charles Darwin once compared the root tips of plants to “the brain of one of the lower animals” he even reported electrical signal systems in plants, much like a nervous system. More than a century after Darwin, a scientist named Mancuso discovered the center for the electrical signals, or action potentials, is located in the root tips. Even small plants had nearly 14 million root tips, all acting in a similar way to a nervous system. Humans and most animals have centralized brains, meaning it is all grouped together in one spot, forming what we envision as a brain. Plants may not have a centralized brain like humans, but that doesn’t mean they lack a brain, in fact plants have “decentralized intelligence” distributed throughout them. Since plants cannot react quickly, they have no way of defending themselves against predators, so by scattering the “brain” plants avoid dying off when damaged (Marinelli). The root tips and sensory cells allow plants to feel and react to different stimuli. It is uncertain as to whether plants feel pain, but they do respond to anesthetics and react to being damaged. For example, when a caterpillar eats a plant’s leaf, the plant begins to secrete defensive chemicals. The censor cells react to the damage being done and cause the leaf to secrete chemicals to fend off the predator, as well as repair the
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.
Parasites and their Virulence Why do some parasites kill the host they depend upon while others coexist with their host? Two prime factors determine parasitic virulence: the manner in which the parasite is transmitted, and the evolutionary history of the parasite and its host. Parasites which have colonized a new host species tend to be more virulent than parasites which have coevolved with their hosts. Parasites which are transmitted horizontally tend to be more virulent than those transmitted vertically. It has been assumed that parasite-host interactions inevitably evolve toward lower virulence.
Schumann, Gail L., and Cleora J. D'Arcy. Hungry Planet: Stories of Plant Diseases. St. Paul: American Phytopathological Society, 2012. Print.
Another study proposed that CR slowed aging process by increasing resistance to hyperoxidation. As aging progressed in yeast and other animals, the presence of free radicals increased in the cells. Usually, the levels of the...
On the other hand, senescence process including senescence rate and molecular nature is influenced by various environmental and internal factors (Lim et al., 2007). The internal factors influencing leaf senescence includes phytohormones such as cytokinins, ethylene, auxin, JA, ABA, and SA, while the external factors includes UV rays , nutrient limitation, temperature, drought, shading, and pathogen attach or wounding. It can be said that to form a complex network of regulatory pathways for senescence, there should be an existence of various pathways responding to several external and internal factors all the pathways should be interconnected (He et al., 2001). Having said that, leaf senescence should be an excellently regulated process, taking into account its potential role in plants health and the various factors involved in senescence control (Lim et al.,
1999). Fungal pathogens that have been discovered in Arabidopsis plants, such as Rhizopus niveus, are made of several different types of lipases, including triacylglycerol lipases (Falk et al. 1999). Therefore, when an Arabidopsis plant encounters these fungal enzymes, the contained lipids are hydrolyzed by the EDS1 proteins and the fungal pathogen is
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.
shows how different abiotic stresses result in unique responses from a plant cell wall [4].
The plants that we know today as terrestrial organisms were not always on land. The land plants of today can be linked back to aquatic organisms that existed millions of years ago. In fact, early fossil evidence shows that the earliest land plants could have arisen some 450 million years ago (Weng & Chappie 2010). Plants that used to reside strictly in water were able to adapt in ways that allowed them to move onto land. It is speculated the need for plants to move onto land was created by water drying up, causing plants to have less room and pushing them to move onto land. Although the exact cause of plant’s need to move to a terrestrial environment is unclear, it is known that plants had to undergo several adaptations to be able to live on land. These adaptations include: lignin, cellulose, suberin, and changes to plant’s surface, including the formation of a waxy cuticle.
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.
Plants are grown under controlled and sterile conditions which reduce the risk of being exposed to pests, pathogens and diseases.
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).
Gain of Function or Gain or Risk? In the world of viral research today, the study of Enhanced Pathogens is a risky, if not dangerous, field of research. The big question regarding research on enhanced pathogens stands with: is deeper knowledge about the pathogen worth the risk of accidentally spreading them, or is it too hazardous? Well, Enhanced Pathogens are dangerous, but they aren't as dangerous and complicated as they seem to be. In fact, they are the least harmful in a few cases, but still can cause some troubles along the way.