Molecular variation of satellite DNA beta molecules associated with Malvastrum yellow vein virus and their role in pathogenicity.

Previous studies have found that the diversity of begomovirus-associated DNA beta satellites is related to host and geographical origin. In this study, we have cloned and sequenced 20 different isolates of DNA beta molecules associated with Malvastrum yellow vein virus (MYVV) isolated from Malvastrum coromandelianum plants in different geographical locations of Yunnan Province, China. Analyses of their molecular variation indicate that the satellites are clustered together according to their geographical location but that they have only limited sequence diversity. Infectivity tests using infectious clones of MYVV and its associated DNA beta molecule indicate that MYVV DNA beta is indispensable for symptom induction in Nicotiana benthamiana, N. glutinosa, Petunia hybrida, and M. coromandelianum plants. Furthermore, we showed that MYVV interacts functionally with heterologous DNA beta molecules in N. benthamiana plants.