Tulip breaking virus

Tulip breaking virus is one of five plant viruses of the family Potyviridae that cause color-breaking of tulip flowers. These viruses infect plants in only two genera of the family Liliaceae: tulips (Tulipa) and lilies (Lilium). Tulip breaking virus is one of five plant viruses of the family Potyviridae that cause color-breaking of tulip flowers. These viruses infect plants in only two genera of the family Liliaceae: tulips (Tulipa) and lilies (Lilium). Also known as the tulip break virus, lily streak virus, lily mosaic virus, or simply TBV, Tulip breaking virus is most famous for its dramatic effects on the color of the tulip perianth, an effect highly sought after during the 17th-century Dutch 'tulip mania.' Tulip breaking virus is a potyvirus — a member of the group whose type species is potato virus Y. A distant serological relationship between Tulip breaking virus and tobacco etch virus was discovered in 1971. Tulip breaking virus (TBV), tulip top-breaking virus (TTBV), tulip bandbreaking virus (TBBV), Rembrandt tulip-breaking virus (ReTBV), and lily mottle virus (LMoV) have all been identified as potyviruses by serology and potyvirus-specific polymerase chain reaction (PCR). In addition, sequence analysis of amplified DNA fragments has classified them all as distinct viruses or strains; recently TTBV has been found to be strain-related to turnip mosaic virus. The virus infects the bulb and causes the cultivar to 'break' its lock on a single color, resulting in intricate bars, stripes, streaks, featherings or flame-like effects of different colors on the petals. These symptoms vary depending on the plant variety and age at the time of infection. Different types of colour-breaks depend on the variety of tulip and the strain of the virus. The color variegation is caused either by local fading, or intensification and overaccumulation of pigments in the vacuoles of the upper epidermal layer due to the irregular distribution of anthocyanin; this fluctuation in pigmentation occurs after the normal flower color has developed. Because each outer surface is affected, both sides of the petal often display different patterns. In the lily species, the virus causes mild to moderate mottling or streaking in the leaves about two weeks after inoculation, and then causes the plant to produce distorted leaves and flowers. The virus also weakens the bulb and retards the plant's propagation through offset growths; as it progresses through each generation the bulb grows stunted and weak. Eventually it has no strength to flower, and either breaks apart or withers away, ending the genetic line. For this reason the most famous examples of tulips from color-broken bulbs – the Semper Augustus and the Viceroy – no longer exist. Long thought to be the earliest recorded plant virus, it is now thought that TBV comes second; the earliest reference to a virus-induced leaf chlorosis (possibly tobacco leaf curl virus) was recorded in Japan in 752 AD. 'Breaking' symptomology was first described in 1576 by Carolus Clusius, a Flemish professor of Botany at Leiden, who noted the variegation, or 'rectification', so termed because it was believed that with the offset production of an entirely new 'broken' bloom the plant was distilling, or rectifying, itself into a pure life form.