Phytoplasma Life Cycle – What Is Phytoplasma Disease In Plants?
The life cycle of phytoplasma is very complex. Phytoplasmic cells are called zooids or zonate cells. Zooid cells are part of the plant cell wall (phylosphere). They produce chlorophyll and other substances which make up the green color of plants. A single zooid may contain many different kinds of cells. Each kind of cell produces its own substance and makes up the whole organism.
Zooids are not just living organisms but they have a great influence on plant growth. They regulate the development of plants and their function is similar to that of human organs such as kidneys, liver, heart, lungs etc. Some zooids are parasitic and some are not. Parasitic zooids live inside other animals or plants.
Zooids that are not parasitic can survive independently.
Phytoplasma is one of the smallest and most common types of zooids. It has the smallest genome ever found in an organism and it is the smallest known virus on earth. It causes many diseases in plants, animals and even human beings.
Phytoplasma is a very small, non-enveloped virus which contains only one strand of circular DNA. It has been proved that it is the main cause of many plant diseases. It can also be found in humans and animals. It causes a large number of plant diseases which harm the leaves, flowers, fruits, branches and roots of plants.
The most well-known disease caused by these viruses is the citrus greening disease in citrus trees. It is also found in many other plants besides citrus trees such as tomatoes. Another disease caused by these viruses is the Rose Cold in roses.
The viruses are transferred from one plant to another during the process of grafting. The symptoms begin to appear after some time has passed. They only affect the newest growths on the plants, such as the flowers, leaves and stems. The older parts of the plants remain healthy and are not harmed at all.
Some fungal and bacterial diseases can also cause similar symptoms, but their patterns of attack are different. These viruses can be identified through a tissue culture test. In this test, a small sample of plant tissue is grown in a laboratory by placing it in a Petri dish filled with nutrients and hormones. If the sample is infected with a virus, the virus will also infect the culture.
In some cases, these viruses can jump from one species of plant to another. For example, the Bean Yellow Mosaic Virus cannot affect legumes, but it can cause a disease in tomatoes and other plants. It causes yellow mosaic on the older leaves of the plant and yellow rings or arcs appear on the fruits.
The viruses which can be identified through a tissue culture test are usually eliminated through special sterilization methods. If necessary, the plant can be treated with certain kinds of antibiotics. Sometimes, the plant may have to be destroyed.
Surprisingly, not many studies have been done on the phytoplasma viruses in spite of their harmful effects on plants. It is important to find out more about these viruses because they can easily be spread through infected seeds and other planting materials. The symptoms of the diseases caused by these viruses may be reduced or eliminated through genetic engineering.
It is not known how the phytoplasma viruses are spread from one plant to another. One theory claims that an insect vector may carry the virus from one plant to another or even from one part of the world to another. Another theory claims that the virus can survive in the soil for long periods of time and it may remain active even through winter.
Some of the phytoplasma viruses can also infect animals. The well-known African Swine Fever is one such disease. The virus causes a high fever in pigs and it is spread through their saliva. It is very difficult to eliminate this virus because it can survive in the carcasses of infected pigs for long periods of time.
In fact, this virus can even remain active in pig-derived products, such as pork meat and lard.
Some viruses can also persist in the environment without a host. One example is the Tomato Yellow Leaf Curl virus, which can remain active in the soil for long periods of time. In fact, this virus can even remain active in the garden waste left over from previous plantings. This virus spreads itself from one plant to another through insects, such as aphids and leafhoppers.
There are many types of plant viruses and it isn’t known how many have been identified so far. New viruses are still being found and many of them haven’t even been studied yet.
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Citric Acid in Fruit
From: The Food File by Karen Dayle
Citric acid is the substance that makes lemons taste sour. It is also a natural byproduct of many living things, including people. The sour taste of lemons and other citrus fruits comes from citric acid. The citric acid in lemons may prevent tooth decay and has antioxidant properties, which protect body cells from damage.
In addition to lemons, other foods rich in citric acid include oranges, grapefruit, limes, and tamarinds. Many people don’t realize that most fruits contain citric acid. In fact, most fruits contain some citric acid, but lemons and limes have the highest amounts.
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How to sterilize your cutting tools
From: The Food File by Karen Dayle
There are several ways you can sterilize your cutting tools:
Oven or toaster oven: Preheat the oven to 350 degrees F. Place your tools on a cookie sheet and put it in the oven for 15 minutes. Make sure the handles do not touch the oven rack. After 15 minutes, turn off the oven and leave the tool inside until cool.
High alcohol flame: Use a lighter or other high alcohol flame (such as that of a candle) to burn the surface of the cutting tool. Move the flame around the surface of the tool so that the entire surface gets hot. This will sterilize the cutting tool.
Sources & references used in this article:
Phytoplasmas: bacteria that manipulate plants and insects by SA Hogenhout, K Oshima, ELD AMMAR… – Molecular plant …, 2008 – Wiley Online Library
The’life cycle’of pear decline phytoplasma in the vector Cacopsylla pyri by L Carraro, N Loi, P Ermacora – Journal of Plant Pathology, 2001 – JSTOR
Diverse targets of phytoplasma effectors: from plant development to defense against insects by A Sugio, AM MacLean, HN Kingdom… – Annual review of …, 2011 – annualreviews.org
Transmission of Apple Proliferation Phytoplasma by Cacopsylla melanoneura (Homoptera: Psyllidae) by R Tedeschi, A Alma – Journal of Economic Entomology, 2004 – academic.oup.com
Phytoplasmas associated with papaya diseases in Australia. by KS Gibb, DM Persley, B Schneider, JE Thomas – Plant Disease, 1996 – cabdirect.org
Molecular biology and pathogenicity of phytoplasmas by C Marcone – Annals of Applied Biology, 2014 – Wiley Online Library
Data on the life cycle of Cacopsylla pruni, Psyllidae vector of European stone fruit yellows (ESFY) phytoplasma, in France by G Labonne, J Lichou – … Virus and Virus-like Diseases of Temperate Fruit …, 2003 – actahort.org