ORIGINAL ARTICLE Molecular characterization and infectivity analysis of a bipartite begomovirus associated with cotton leaf curl Multan betasatellite naturally infecting Rumex nepalensis in northern India Dolly Sharma 1 & Aditya Kulshreshtha 1,2 & Poonam Roshan 1,2 & Vipin Hallan 1,2 Received: 18 April 2018 /Accepted: 16 March 2019 # Società Italiana di Patologia Vegetale (S.I.Pa.V.) 2019 Abstract Rumex nepalensis (Nepal Dock) is an Indian traditional medicinal herb of the Western Himalayas. During a survey in 2013, typical begomovirus-like symptoms were observed on naturally grown R. nepalensis in the Bandla region of Palampur, Himachal Pradesh, India. PCR-based detection identified a bipartite begomovirus and a betasatellite in all the symptomatic plant samples. Complete sequence characterization established their identity as tomato leaf curl Palampur virus (ToLCPalV) and cotton leaf curl Multan betasatellite (CLCuMuB), respectively. Infectious clones of the virus and betasatellite were agro-infiltrated on both natural (R. nepalensis) as well as experimental (Nicotiana benthamiana) hosts. At 25 days post infiltration (dpi), N. benthamiana developed typical virus symptoms in DNA-A + DNA-B and DNA-A + DNA-B + CLCuMuB-infiltrated plants, whereas the plants infiltrated with DNA-A alone did not show any diseased phenotype. However, in combination with CLCuMuB, mild symptoms were observed. Agro-infiltrated R. nepalensis plants did not show visible symptoms in any of the above combinations. PCR and Southern blot analysis confirmed the replication and systemic spread of ToLCPalV and CLCuMuB in both R. nepalensis and N. benthamiana infiltrated plants. The present report shows R. nepalensis as a new natural host of the bipartite ToLCPalV associated with CLCuMuB. It also demonstrates the efficient trans-replication compatibility of CLCuMuB by a bipartite ToLCPalV in both of its natural and experimental hosts. Keywords Tomato leaf curl Palampur virus . Virus-infected Rumex nepalensis . Bipartite begomovirus, . Betasatellite trans-replication Introduction Rumex nepalensis (family Polygonaceae) is a perennial herb widely distributed in the temperate Himalayas at an altitude of 900–4300 m. This plant is a highly reputed medicinal herb in Indian traditional medicine, which grows on moist, dry slopes and shady areas. Several bioactive metabolites and anthraqui- nones, naphthalenes, flavanoids and other phenolic com- pounds have been reported from R. nepalensis (Liang et al. 2010). Traditionally, this plant is utilized for the treatment of colic and syphilitic ulcers, bleeding, tumors, inflammation, pain and constipation. The roots of R. nepalensis have purga- tive, antibacterial, antipyretic and anti-inflammatory activity (Ghosh et al. 2003; Vasas et al. 2015; Venkatesh et al. 2003). Viruses of the family Geminiviridae are characterized by twinned icosahedral particles that encapsidate circular ssDNA and infect both monocots and dicots. Taxonomically, this fam- ily consists of nine genera, Becurtovirus, Begomovirus, Capulavirus, Curtovirus, Eragrovirus, Grablovirus, Mastrevirus, Topocuvirus, and Turncurtovirus (Zerbini et al. 2017). The genus Begomovirus has the largest number of spe- cies (>320) and its members are transmitted by the whitefly Bemisia tabaci. They infect a large number of economically important crops, and have either a bipartite (both DNA-A and DNA-B components) or a monopartite genome [only one ge- nomic component similar to DNA-A of bipartite begomovirus genome (Zerbini et al. 2017)]. DNA-A of the Old World (OW) bipartite begomoviruses encodes six ORFs: AV1, coat protein Dolly Sharma and Aditya Kulshreshtha contributed equally to this work. * Vipin Hallan hallan@ihbt.res.in 1 Plant Virology Lab, Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Palampur, Himachal Pradesh 176061, India 2 Academy of Scientific and Innovative Research (AcSIR), CSIR-IHBT, Palampur, Himachal Pradesh 176061, India Journal of Plant Pathology https://doi.org/10.1007/s42161-019-00295-6