Blight
Blight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this symptom are called blights. Several notable examples are:
Ralstonia solanacearum
Ralstonia solanacearum is an aerobic nonspore-forming, Gram-negative, plant pathogenic bacterium. "R. solanacearum" is soil-borne and motile with a polar flagellar tuft. It colonises the xylem, causing bacterial wilt in a very wide range of potential host plants. It is known as Granville wilt when it occurs in tobacco. Bacterial wilts of tomato, pepper, eggplant, and Irish potato caused by "R. solanacearum" were among the first diseases that Erwin Frink Smith proved to be caused by a bacterial pathogen. Because of its devastating lethality, "R. solanacearum" is now of the more intensively studied phytopathogenic bacteria and bacterial wilt of tomato is a model system for investigating mechanisms of pathogenesis.
"Ralstonia" was recently classified as "Pseudomonas" with similarity in most aspects, except that it does not produce fluorescent pigment like "Pseudomonas". The genomes from different strains varies from 5.5 Mb up to 6 Mb, roughly being 3.5 Mb of a chromosome and 2 Mb of a megaplasmid. While the strain GMI1000 was one of the first phytopathogenic bacterias to have its genome completed, the strain UY031 was the first "R. solanacearum" to have its methylome reported. Within the "R. solanacearum" species complex, the four major monophyletic clusters of strains are termed phylotypes, that are geographically distinct: phylotypes I-IV are found in Asia, America, Africa, and Oceania, respectively.