The following points highlight the eight modes of transmission of plant viruses. The modes are: 1. Mechanical Transmission 2. Vegetative and Graft Transmission 3. Pollen Transmission 4. Seed Transmission 5. Nematode Transmission 6. Fungal Transmission 7. Insect Vector Transmission 8. Dodder Transmission. Mode # 1. Mechanical Transmission: In nature plant viruses are mechanically transmitted from diseased to healthy plants by [...]
The below mentioned article provides notes on retroviridae. The family Retroviridae falls under the Group VI (ssRNA-reverse transcribing viruses). The virions are enveloped, helical or isometric having two linear (+) sense ssRNA, reverse transcriptase and integrase. Examples are MLV [Murine leukemia virus and related virus e.g. Spumavirus (human foamy virus)], Lentivirus (human immunodeficiency virus or HIV), Visna virus, Deltaretrovints, Alpharetrovims. [...]
In this article we will discuss about:- 1. Origin of Viroid 2. Meaning of Viroids 3. Viroid Genome 4. Replication. Origin of Viroid: So far no sufficient information is available that can lend support for the origin of viroids. Following are some of the speculations regarding the origin of viroids: (a) Viroids are supposed to be the primitive viruses and [...]