Comparison of the Symptoms Caused by Three Geminiviruses in a Common Host

Abstract

The Geminiviridae are a family of single-stranded DNA plant viruses that cause severe crop destruction especially in the tropics. Much of the research into geminivirus replication and resistance is conducted in model organisms such as Nicotiana benthamiana, which is not the natural host of the viruses. Model plants are used because of their ease of cultivation and shorter generation times. Typically, begomoviruses have narrow host ranges and cannot be compared directly. However, unlike many plant species, N. benthamiana is susceptible to a variety of begomoviruses and can be used to compare them in a common host. In this study, we compare the disease properties of three begomoviruses whose natural hosts include cabbage and cassava, which represent two families – the Brassicaceae and Euphorbiaceae. These studies examine Cabbage leaf curl virus (CaLCuV), African cassava mosaic virus-Cameroon (ACMV-Cam) and East African cassava mosaic virus-Uganda (EACMV-UG3). CaLCuV infects cabbage, cauliflower and broccoli fields in the U.S. The two cassava-infecting viruses are part of a disease complex that causes Cassava Mosaic Disease (CMD) in Africa. CMD is pandemic across Africa, resulting insufficient food supplies. We infected N. benthamiana with ACMV-Cam and EACMVUG3 by bombardment of cloned viral sequences. CaLCuV was inoculated using Agrobacteria carrying viral genomic DNA in T-DNA plasmids. The infected plants were monitored for symptoms and viral DNA accumulation. These studies showed that CaLCuV and ACMV-Cam caused the most severe symptoms on N. benthamiana and were similar in severity. EACMV-UG3 symptoms were significantly milder.