The interaction between plant hosts and pathogens are complex systems that consist of a vast multitude of components. These components that contribute to these systems are from host as well as pathogenic origin and compete with one another in an attempt to be more successful than the other party.
There are many different pathogens that infect plants from all five kingdoms of life and each has a different method of infecting the host. There are several traits that are universal requirements for infection such as gaining entry to the host, overcoming the host’s immune response, replicating effectively within the host and spreading to naïve hosts.
Plant cell walls consist of a network of various peptides and polysaccharides. Three categories of polysaccharides exist, namely cellulose, hemicellulose and pectin. Pectin and hemicellulose form the network that the cellulose microfibrils are embedded. The pectin network consists of galacturonic acid (PGA) subunits that are bound by α-1,4-linked glycosidic bonds. This network acts as a primary defence barrier to pathogens that attempt to cross the cell wall to infect the host as well as providing significant structural support.
The biosynthesis of pectin is localised to the Golgi vesicles. It has been estimated that 67 different enzymes are required in the biosynthetic pathway of pectin. 384 The reason for the evolution of pectin is mostly unknown and genome comparisons between different plants would provide a clearer insight into its evolution. What is known about the evolution is that the latest development in angiosperms is the presence of the QUA1 ortholog.
Plant endoPGs are important for the developmental and remodelling processes during their lifecycles.
One of the most prolific en...
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...able to produced polygalacturonase-inhibiting proteins (PGIPs) to protect themselves. PGIPs are able to defend themselves against fungal endoPGs, but not against bacterial endoPGs. This has led to the biochemical and computational study of various endoPG enzymes from various sources.
EndoPG have many commercial applications that include extraction of fruit juice and vegetable oils, bleaching of paper, the treatment of waste water and as additives in poultry feed.
References
Oeser, B., Heidrich, P.M., Muller, U., Tudzynski, P., Tenberge, K.B., 2002, Polygalacturonase is a pathogenicity factor in the Claviceps purpurea/rye interaction, Fungal Genetics and Biology, 36: 176–186
Wu, C., Yan, H., Liu, L., Liou, R., 2007, Functional Characterization of a Gene Family Encoding Polygalacturonases in Phytophthora parasitic, Molecular Plant-Microbe Interactions, 21(4): 480-489
One of the main questions addressed is; why do plants choose rhizobia with nitrogen fixing strains (as nitrogen is metabolically costly) over plants with non-fixing strains that can also lead to nodulated plant (Gubry-Rangin et al, 2010). It should be noted that strains with different fixing levels have been reported in populations of rhizobia and when picking a rhizobium a plant must take into consideration its symbiotic efficacy, as rhizobia cannot be vertically transmitted.
A pathogen can be anything that causes a disease, including bacterium which causes meningitis, Viruses causing hepatitis A-C, and a fungus that cause athlete's foot. Plant pathology bacteria can serve economically damaging diseases, from spots, pustules on leaves and fruit, tuber rots to a plant's death. Some bacteria causes a hormone base distortion of leaves and shoots called fasciation. Fungi pathogens spread through plants to steal nutrients of living plants and carry out the part of the life cycle in soil. Mycorrhizae fungi make carbohydrates from plant roots, enhancing plant uptake of inorganic nutrients such as phosphorus and nitrogen. Cripps, C.L reported on mycorrhizae that “ The relationship is considered nonpathogenic, and of benefit to the plants involved.”- describing that the relationship between mycorrhizae and pathogens is nonpathogenic because mycorrhizae cancels out the disease. Over 85% of plants in nature have the mycorrhizae condition to keep pathogens away. This is why gardeners buy mycorrhizae fungi to help stop diseases of plants and for the safety of humans catching the disease through eating the plants. Food is one of the most important factors in the ecology life cycle and mycorrhizae makes it safe for these plants to take part in the
The basis for the symbiotic relationship in these species is complex. The infection of the host cell by rhizobia occurs within the plant’s root nodules. Bacteroides, gram-negative anaerobic bacteria, are isolated from the host cell by a peribacteroid membrane; the membrane between the plasma membrane of the cell and the membrane of the bacteroid. The bacteroid contains differentiated rhizobia, which are able to fix nitrogen due to the supply of carbon from the host plant. Sucrose is delivered to the nodules of the root via the phloem, where it is cleaved by suc synthase, and enters the Krebs cycle. The product of glyco...
Rhee, S. Y., W. Beavis, et al. (2003). "The Arabidopsis Information Resource (TAIR): a model organism database providing a centralized, curated gateway to Arabidopsis biology, research materials and community." Nucl. Acids Res. 31(1): 224-228.
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.
Schumann, Gail L., and Cleora J. D'Arcy. Hungry Planet: Stories of Plant Diseases. St. Paul: American Phytopathological Society, 2012. Print.
Smith, A.M., Coupland, G., Dolan, L., Harberd, N., Jones, J., Martin, C., Sablowski, R. and Amey, A., 2010. Plant biology. New York: Garland Science; Taylor & Francis distributor.
Pectin is a substrate that binds to the enzyme pectinase. Pectinase breaks down the pectin and changes the pectin into the product of the chemical reaction. Therefore in this case, pectin in applesauce binds to pectinase and then is broken down into the apple juice. The same chemical reaction would occur with cellulose changing into apple juice after being bound to the enzyme cellulase. However, background research suggests that pectinase creates more apple juice. Apples are one of the best sources of pectin possible (Andrew). Because of the particular abundance of pectin in apples, applesauce works more with pectinase than with cellulase. Cellulose is said to be more abundant in Brussels sprouts, potatoes and squash rather than apples (Fialkoff). Because of this principle, it is logical to conclude that pectinase extracts the most apple juice out of
The work of Reese in 1950 helped in elucidating an understanding of the complex action of cellulases. The two-step degradation process as suggested by Reese requires an activation reaction followed by hydrolytic cleavage. The activating but non-hydrolyzing enzyme was named as C1 activity. According to this concept, micro-organisms having the potential to degrade crystalline cellulose have C1 activity. This potential has not been seen in enzymes that attack only substituted cellulose like carboxymethylcellulose (CMC) or hydroxyethylcellulose (HEC). They have only Cx activity (Reese,
Interactions in between plant species are of great importance and often result in fierce competition within the community. Over the past decades, increasing in human activity and movement allowed certain species to migrate beyond their origins and vastly expand in population, plants being one of the most complicated organisms on earth were highly involved in such activity. This enabled invasions by alien plants which poses serious threats and may inflict negative impacts to native species of plants in an certain ecosystem. Due to this nature, it may be concluded that there are certain traits and characteristics in these plants that allowed for the dominance to occur. It is crucial to be able to identify these traits to prevent
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.
Based on the genetic structure of glgC (code V00281.1) encoding AGPase enzymes in E. coli has been published in GenBank and characteristics of the AGPase enzyme in plants, we modified the sequence of glgC gene by creating G336D mutation.
...ass soil. This demonstrates that a pathogen may influence allelopathy between plants and that rust may enhance ryegrass allelopathy against clover (Mattner 2001).
Rice plants are frequently under attack from various insects, pest and pathogens. Most of the elite rice cultivars and varieties with favorable taste and yield such as Basmati, Sambha Mashuri, Swarna, other aromatic rice etc. are very much prone to diseases. Bacterial blight (BB) is one of the major diseases of rice affecting as much as 20-50% yield loss in severe cases (Reddy 1989; Mew 1993; Adhikari et al. 1994). Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight disease in rice. It is a vascular disease resulting in systemic infection. To control the disease, use of chemical pesticides, biological control agents and host mediated resistance have been widely adopted. However, spraying pesticides have tremendous long term ill effects to environment and consumers. In order to provide durable, economical and sustainable disease resistance to plants, host ...