Pathogenicity and stability of a truncated DNAbeta associated with Tomato yellow leaf curl China virus.

DNAbeta molecules are single-stranded satellite DNA associated with monopartite begomoviruses (family Geminiviridae). DNAbeta possesses a C1 gene on the complementary strand, which has a conserved position and size. To better understand the function of C1 gene in virus infection, a C1 deletion DNAbeta associated with a Tomato yellow leaf curl China virus (TYLCCNV) isolate was constructed. Co-agroinoculation with TYLCCNV showed the truncated DNAbeta was infectious in Nicotiana benthamiana and N. glutinosa plants but not in N. tabacum Samsun, N. tabacum and Lycopersicon esculentum plants. The wild-type TYLCCNV DNAbeta co-agroinoculated with TYLCCNV caused systemic infection in all the above hosts. Results of Southern blot analysis indicate that C1 gene is not required for TYLCCNV and DNAbeta replication. However, the presence of C1 gene in DNAbeta can increase both TYLCCNV and DNAbeta accumulation in infected plants. The truncated TYLCCNV DNAbeta was stable in N. benthamiana and N. glutinosa plants.