Function of A-Rich region in DNAβ associated with Tomato yellow leaf curl China virus

A novel type of circular single-stranded satellite DNA, known as DNAβ, was recently characterized and demonstrated to be associated with monopartite begomoviruses. DNAβ was essential for induction of characteristic symptoms in plants. DNAβ has three structural features: an 115 bp highly conserved region, tiC/gene and A-Rich region. The in-frame ATG mutation of βC1 gene of Tomato yellow leaf curl China virus isolate Y10 (TYLCCNV-TY10) DNAβ demonstrated that βC1 gene is required for leaf curl symptom. Here, the function of A-Rich region in TYLCCNV-Y10 DNAβ was identified. When A-Rich region was deleted, the A-Rich deleted mutant was still capable of replication and systemic infection in plant, indicating that A-Rich region is not required for trans-replication of DNAβ. The immunotrapping-PCR demonstrated that A-Rich deleted mutant could be encapsidated in the coat protein encoded by TYLCCNV-Y10 DNA-A, suggesting that A-Rich region is not related with DNAβ encapsidation. However, the A-Rich region deleted mutant caused milder symptom.