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Plant pathogens, organisms that cause infectious plant diseases, include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. [2] In most plant pathosystems, virulence depends on hydrolases and enzymes that degrade the cell wall.
More recently virus research has been focused on understanding the genetics and molecular biology of plant virus genomes, with a particular interest in determining how the virus can replicate, move and infect plants. Understanding the virus genetics and protein functions has been used to explore the potential for commercial use by biotechnology ...
Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1] Organisms that cause infectious disease include fungi , oomycetes , bacteria , viruses , viroids , virus -like organisms, phytoplasmas , protozoa , nematodes and parasitic plants . [ 2 ]
The symptoms appeared on plants onto which pieces from affected plants had been budded—indicating that the disease was caused by a transmissible pathogenic agent. A fungus or bacterium could not be found consistently associated with symptom-bearing plants, however, and therefore, it was assumed the disease was caused by a virus. Despite ...
References to diseases now known to be caused by phytoplasmas can be found as far back as 1603 (mulberry dwarf disease in Japan). [4] Such diseases were originally thought to be caused by viruses, which, like phytoplasmas, require insect vectors and cannot be cultured. Viral and phytoplasmic infections share some symptoms. [5]
Bacterial wilt is a disease of the vascular tissue. When a plant is infected, E. tracheiphila multiplies within the xylem , eventually causing mechanical blockage of the water transport system. The first sign of infection, which appears about five days after acquisition, is the wilting of individual leaves on a single stem.
Cacao swollen-shoot virus has a double stranded circular DNA genome that is 7.4 kb in size and bacilliform in structure. [1] It is transmitted primarily through mealybug (Pseudococcidae) vectors. Once within the host, the virus uses the host to replicate. The virus codes for RNA silencing genes, which turn off the host plant's defenses.
Vectors either transmit the virus propagative transmission, which results in an amplification of the virus by replication within the cells of the vector, or non-propagative transmission which simply carries the virus between the plants without viral replication. Common vectors include bacteria, fungi, nematodes, arthropods and arachnids.