Tulip Breaking Virus - Pathogen Discovery

Pathogen Discovery

By the mid-1920s, biochemistry was coming into its own, and its impact was felt in virus research. Eventually, it was series of bulb manipulation experiments begun in 1928 by Dorothy Cayley at the John Innes Horticultural Institution in Norfolk, England that led to the discovery of the virus. Cayley discovered that by mechanically transferring infected tissue from broken bulbs to healthy bulbs during their dormant state, the virus that caused the break in color would also be transferred. These experiments were further refined down to minute amounts, which led her to correctly conclude that the "virus or enzyme infection" was sap-transmissible, probably transferred by an insect, and the degree of breaking was proportional to the amount of infected tissue introduced.

The virus was eventually proved to be transferred in a non-persistent manner by at least four species of aphids, specifically Myzus persica (the most efficient), Macrosiphum euphorbiae, Doralis fabae and Aphis gossypii. McKenny-Hughes reported in 1934 that Yezabura tulipae transmitted the virus between stored tulip bulbs, but this has not been confirmed. The transfer of the virus is non-persistent, which means it is accomplished through the insect feeding. In non-persistent transmission, viruses become attached to the distal tip of the stylet in the insect's mouthparts, so that the next plant it feeds on is inoculated with the virus. The virus does not affect the seed that produces a bulb, only the bulb itself, its leaves and blooms, and its daughter offsets.

It was not until the 1960s that TBV was shown to have flexuous filamentous particles (mostly measuring about 12×750 nm) and finally proved to be a virus. The genetic code of TBV has now been partially sequenced and the virus is recognized as a member of the genus Potyvirus (family Potyviridae). Like other members of the genus it is now readily detected and identified by serological and molecular techniques.