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

DNAβ molecules are single-stranded satellite DNA associated with monopartite begomoviruses (family Geminiviridae). DNAβ 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 DNAβ associated with a Tomato yellow leaf curl China virus (TYLCCNV) isolate was constructed. Co-agroinoculation with TYLCCNV showed the truncated DNAβ 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 DNAβ 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 DNAβ replication. However, the presence of C1 gene in DNAβ can increase both TYLCCNV and DNAβ accumulation in infected plants. The truncated TYLCCNV DNAβ was stable in N. benthamiana and N. glutinosa plants.