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| Erwinia papayae | |
|---|---|
Scientific classification  | |
| Domain: | Bacteria |
| Phylum: | Pseudomonadota |
| Class: | Gammaproteobacteria |
| Order: | Enterobacterales |
| Family: | Erwiniaceae |
| Genus: | Erwinia |
| Species: | E. papayae |
| Binomial name | |
| Erwinia papayae Gardan et al., 2004 | |
Erwinia papayae is a bacteria species causing bacterial crown rot, or bacterial canker, a noteworthy and grave disease of papaya ( Carica papaya ).
Erwinia papayae, the bacterial pathogen responsible for the disease, was first identified in 1931 in Java, Indonesia (Gardan et al. 2004), and has since spread to papaya growing countries worldwide—from the Caribbean to South America to South East Asia (Ollitrault et al. 2007). By the late 1960s, E. papayae had appeared in the West Indies, where it obliterated all the yields of the papaya cultivar ‘Solo,’ which because of its high fruit yields and quality was the only one grown in the fields (Ollitrault et al. 2007). Papayas are significant cash crops for the papaya-growing countries because of their rapid generation, high yields, and large market demand both locally and internationally (Ollitrault et al. 2007). In Malaysia, where the disease has plagued farmers for over a decade, papayas have an export value of approximately 24-28 million USD per year (Maktar et al. 2008). With bacterial crown rot affecting approximately 800 hectares of papaya on the Malaysian Peninsula alone (Maktar et al. 2008), this results in a huge loss in profit for the agricultural industry.[ citation needed ]
Although Erwinia papayae has been known to survive on leaves of cowpea, tomato, and rockmelon for a minimum of two weeks, the host range of bacterial crown rot is confined to papaya (Webb 1985). Inoculation with the pathogen of twenty-three common weed species and crops found in association with Philippine papaya fields found none of these species to be susceptible to the disease (Obrero 1980). Symptoms of bacterial crown rot begin as angular water-soaked lesions on leaf surfaces and eventually spread through veins and petioles to cause death to the canopy layer of leaves. Water-soaked cankers also appear on the stem, causing it to collapse, and spread to meristems, killing the growing tips of the plant (Webb 1985; Fullerton et al. 2011; Maktar et al. 2008). Water-soaked lesions can also appear on unripe fruit, and although they start small, the lesions can turn into firm depressions (Webb 1985). Dry conditions can allow infected plants to recover and produce unaffected, fruit-producing branches. Erwinia papayae is a Gram-negative, straight rod bacterium with peritrichous flagella, so diagnosis can be made using a Gram stain. On King’s medium B, colonies are creamy and mucoid with a non-diffusible blue pigment (Vawdrey 2011).
The pathogen can survive in the seed of infected papaya, even after drying, for approximately 30 days (Obrero 1980). Thus far, seed-borne transmission is the predominant method of spread and infection; in fact, studies indicate the pathogen has the ability for long-range dispersal via seed (Ramachandran et al. 2015). Although symptoms can be seen year round, rain and splashing water aid in the transmission and exacerbate the disease (Webb 1985). The bacterium relies on wounds or natural plant openings to enter the papaya. Upon infection by the pathogen, juvenile stem tissue initially shows dark green, water-soaked lesions, which develop into putrid wet rot on the stems (Vawdrey 2011). E. papayae causes a systemic infection—coalescing brown angular lesions spread from the stem lamina to the crown meristems. The firm depressed lesions that progress on unripe fruit penetrate seed cavities. The pathogen does not survive longer than two weeks in soil—instead, the pathogen survives inside the infected vascular bundles of diseased papaya (Vawdrey 2011).
Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard in a single growing season.
Erwinia is a genus of Enterobacterales bacteria containing mostly plant pathogenic species which was named for the famous plant pathologist, Erwin Frink Smith. It contains Gram-negative bacteria related to Escherichia coli, Shigella, Salmonella, and Yersinia. They are primarily rod-shaped bacteria.
Citrus canker is a disease affecting Citrus species caused by the bacterium Xanthomonas. Infection causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit. While not harmful to humans, canker significantly affects the vitality of citrus trees, causing leaves and fruit to drop prematurely; a fruit infected with canker is safe to eat, but too unsightly to be sold.
Dickeya dadantii is a gram-negative bacillus that belongs to the family Pectobacteriaceae. It was formerly known as Erwinia chrysanthemi but was reassigned as Dickeya dadantii in 2005. Members of this family are facultative anaerobes, able to ferment sugars to lactic acid, have nitrate reductase, but lack oxidases. Even though many clinical pathogens are part of the order Enterobacterales, most members of this family are plant pathogens. D. dadantii is a motile, nonsporing, straight rod-shaped cell with rounded ends. Cells range in size from 0.8 to 3.2 μm by 0.5 to 0.8 μm and are surrounded by numerous flagella (peritrichous).
Phytophthora palmivora is an oomycete that causes bud-rot of palms, fruit-rot or kole-roga of coconut and areca nut. These are among the most serious diseases caused by fungi and moulds in South India. It occurs almost every year in Malnad, Mysore, North & South Kanara, Malabar and other areas. Similar diseases of palms are also known to occur in Sri Lanka, Mauritius, and Sumatra. The causative organism was first identified as Phytophthora palmivora by Edwin John Butler in 1917.
Monilinia fructicola is a species of fungus in the order Helotiales. A plant pathogen, it is the causal agent of brown rot of stone fruits.
Pseudomonas cichorii is a Gram-negative soil bacterium that is pathogenic to plants. It has a wide host range, and can have an important economical impact on lettuce, celery and chrysanthemum crops. P. cichorii was first isolated on endives, from which it derives its name. It produces 6-aminopenicillanic acid. Based on 16S rRNA analysis, P. cichorii has been placed in the P. syringae group.
Pseudomonas savastanoi is a gram-negative plant pathogenic bacterium that infects a variety of plants. It was once considered a pathovar of Pseudomonas syringae, but following DNA-relatedness studies, it was instated as a new species. It is named after Savastano, a worker who proved between 1887 and 1898 that olive knot are caused by bacteria.
Pseudomonas viridiflava is a fluorescent, Gram-negative, soil bacterium that is pathogenic to plants. It was originally isolated from the dwarf or runner bean, in Switzerland. Based on 16S rRNA analysis, P. viridiflava has been placed in the P. syringae group. Following ribotypical analysis misidentified strains of Pseudomonas syringae pv. ribicola and Pseudomonas syringae pv. primulae were incorporated into this species. This pathogen causes bacterial blight of Kiwifruit.
Clavibacter michiganensis is an aerobic non-sporulating Gram-positive plant pathogenic actinomycete of the genus Clavibacter. Clavibacter michiganensis has several subspecies. Clavibacter michiganensis subsp. michiganensis causes substantial economic losses worldwide by damaging tomatoes and potatoes.
Lasiodiplodia theobromae is a plant pathogen with a very wide host range. It causes rotting and dieback in most species it infects. It is a common post harvest fungus disease of citrus known as stem-end rot. It is a cause of bot canker of grapevine. It also infects Biancaea sappan, a species of flowering tree also known as Sappanwood.
Xanthomonas arboricola is a species of bacteria. This phytopathogenic bacterium can cause disease in trees like Prunus, hazelnut and walnut.
Bacterial soft rots are caused by several types of bacteria, but most commonly by species of gram-negative bacteria, Erwinia, Pectobacterium, and Pseudomonas. It is a destructive disease of fruits, vegetables, and ornamentals found worldwide, and affects genera from nearly all the plant families. The bacteria mainly attack the fleshy storage organs of their hosts, but they also affect succulent buds, stems, and petiole tissues. With the aid of special enzymes, the plant is turned into a liquidy mush in order for the bacteria to consume the plant cell's nutrients. Disease spread can be caused by simple physical interaction between infected and healthy tissues during storage or transit. The disease can also be spread by insects. Control of the disease is not always very effective, but sanitary practices in production, storing, and processing are something that can be done in order to slow the spread of the disease and protect yields.
Xanthomonas campestris pv. vesicatoria is a bacterium that causes bacterial leaf spot (BLS) on peppers and tomatoes. It is a gram-negative and rod-shaped. It causes symptoms throughout the above-ground portion of the plant including leaf spots, fruit spots and stem cankers. Since this bacterium cannot live in soil for more than a few weeks and survives as inoculum on plant debris, removal of dead plant material and chemical applications to living plants are considered effective control mechanisms.
Beet vascular necrosis and rot is a soft rot disease caused by the bacterium Pectobacterium carotovorum subsp. betavasculorum, which has also been known as Pectobacterium betavasculorum and Erwinia carotovora subsp. betavasculorum. It was classified in the genus Erwinia until genetic evidence suggested that it belongs to its own group; however, the name Erwinia is still in use. As such, the disease is sometimes called Erwinia rot today. It is a very destructive disease that has been reported across the United States as well as in Egypt. Symptoms include wilting and black streaks on the leaves and petioles. It is usually not fatal to the plant, but in severe cases the beets will become hollowed and unmarketable. The bacteria is a generalist species which rots beets and other plants by secreting digestive enzymes that break down the cell wall and parenchyma tissues. The bacteria thrive in warm and wet conditions, but cannot survive long in fallow soil. However, it is able to persist for long periods of time in the rhizosphere of weeds and non-host crops. While it is difficult to eradicate, there are cultural practices that can be used to control the spread of the disease, such as avoiding injury to the plants and reducing or eliminating application of nitrogen fertilizer.
Gummy stem blight is a cucurbit-rot disease caused by the fungal plant pathogen Didymella bryoniae. Gummy stem blight can affect a host at any stage of growth in its development and affects all parts of the host including leaves, stems and fruits. Symptoms generally consist of circular dark tan lesions that blight the leaf, water soaked leaves, stem cankers, and gummy brown ooze that exudes from cankers, giving it the name gummy stem blight. Gummy stem blight reduces yields of edible cucurbits by devastating the vines and leaves and rotting the fruits. There are various methods to control gummy stem blight, including use of treated seed, crop rotation, using preventative fungicides, eradication of diseased material, and deep plowing previous debris.
Blackleg is a plant disease of potato caused by pectolytic bacteria that can result in stunting, wilting, chlorosis of leaves, necrosis of several tissues, a decline in yield, and at times the death of the potato plant. The term "blackleg" originates from the typical blackening and decay of the lower stem portion, or "leg", of the plant.
Collar rot is a symptomatically described disease that is usually caused by any one of various fungal and oomycete plant pathogens. It is present where the pathogen causes a lesion localized at or about the collet between the stem and the root. The lesions develop around the stem eventually forming a "collar". Observationally, collar rot grades into "basal stem rot", and with some pathogens is the first phase of "basal stem rot" often followed by "root rot". Collar rot is most often observed in seedings grown in infected soil. The pathogens that cause collar rot may be species or genera specific. But generalist pathogens such as Athelia rolfsii are known to attack over 200 different species. While bacteria caused collar rot is not common, trees infected with Fire blight may develop collar rot. Non-parasitic collar rot may be caused by winter damage.
Thousands of plant diseases have been recorded throughout the world, many of these causing heavy crop losses. Early detection and accurate diagnosis is essential for the effective management of plant disease. Thus the first step in studying any disease is its timely detection of the diseased plant. Quick initial detection is largely based on the signs and symptoms of disease.
Papaya Bunchy Top Disease was first discovered in 1931 in Puerto Rico. Early on, the identity of the pathogen was highly contested due to the inability of isolating it; thus Koch’s postulates could not be fulfilled. Scientists have previously believed that Papaya Bunchy Top Disease was caused by a virus, a mycoplasma-like organism (MLO), or a phytoplasma, but these possible pathogens have since been disproven. Since the identity of the pathogen was unknown, all diagnoses were given solely based on a list of commonly associated symptoms. Through sequencing and microscopy, scientists identified the pathogen to be a part of the genus Rickettsia in 1996. The bacterium is described as being rod-shaped, small, gram-negative, and laticifer-inhibiting. Rickettsia causes diseases in animals, such as typhus and spotted fever, as well as in other plants, such as phony disease of peach and almond leaf scorch. Papaya Bunchy Top is found throughout the American tropics and has been economically important due to its major impact on fruit production. There is little information about the current economic impact.
 | This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations .(April 2017) |
Fullerton RA, Taufa L, Vanneste JL, Yu J, Cornish DA, Park D. (2011). First record of bacterial crown rot of papaya (Carica papaya) caused by an Erwinia papayae-like bacterium in the Kingdom of Tonga. Plant Disease 95, 70.
Gardan, L., Christen, R., Achouak, W., & Prior, P. (2004). Erwinia papayae sp. nov., a pathogen of papaya (Carica papaya). International Journal of Systematic and Evolutionary Microbiology 54, 107-113.
Maktar, N. H., Kamis, S., Mohd Yusof, F.Z., & Hussain, N.H. (2008). Erwinia papayae causing papaya dieback in Malaysia. Plant Pathology 57(4), 774.
Obrero, F. P. (1991). Bacterial crown rot of papaya in the Philippines. In: Proceedings of First National Symposium/Workshop on Ring Spot and other diseases of papaya in the Philippines, The Philippine Phyt. Soc. Bureau of Plant Industry, San Andres, Malate, Manila, pp 20–23.
Ollitrault, P., Bruyére, S., Ocampo, J., de Lapeyre, L., Gallard, A., Argoud, L., Duval, M.F., Coppens d’Eeckenbrugge, G., Le Bellec, F. (2007). Papaya breeding for tolerance to bacterial decline (Erwinia sp.) in the Caribbean region. Acta Horticulturae 740, 79-92
Ramachandran, K., Manaf, U. A., Zakaria, L. (2015) Molecular characterization and pathogenicity of Erwinia spp. Associated with pineapple [Ananas comosus (L.) Merr.] and papaya [Carica papaya L.). Journal of Plant Protection Research 55 (4), 396-404.
Vawdrey, L. (2011). Threat Specific Contingency Plant, Bacterial Crown Rot: Erwinia papayae. In: Industry Biosecurity Plan for the Papaya Industry, Plant Health Australia, pp 1–25.
Webb, R.R. (1985). Epidemiology and Control of Bacterial Canker of Papaya Caused by an Erwinia sp. on St. Croix, U.S. Virgin Islands. Plant Disease 69, 305-309.