First report of Bean yellow mosaic virus on Cape gooseberry in India

Cape gooseberry (Physalis peruviana, Solanaceae) is an important crop cultivated in tropical, subtropical and temperate areas for nutritional and medicinal purposes. During a survey in April 2013, a severe mosaic disease was observed on most of the P. peruviana plants growing in a farmer’s field at Barabanki, India. Naturally infected plants exhibited mosaic, leaf distortion and stunting symptoms (Fig. 1a). Sap from infected leaves of P. peruviana was inoculated on seedlings of P. peruviana, Chenopodium amaranticolor, Datura inoxia, Petunia hybrida and Nicotiana glutinosa. Sap inoculations resulted in local lesions on C. amaranticolor 10 days post inoculation (dpi), and systemic mosaic and leaf crinkling on P. peruviana, D.inoxia and P. hybrida (Fig. 1b-d), but not on N. glutinosa 30 dpi. The symptoms on inoculated P. peruviana were similar to those of naturally infected P. peruviana. Flexuous filamentous virus particles of ~750 x 12 nm were observed in leaf dip preparations using an electron microscope, indicating the presence of a potyvirus. 

Total RNA was extracted from leaf samples of three symptom-bearing and one healthy P. peruviana plant and tested by RT-PCR using degenerate potyvirus primers (Ha et al., 2008). A ~700 bp band was amplified from all three plants with symptoms but not from the healthy sample, suggesting potyvirus infection. All amplicons were cloned and sequenced (GenBank Accession Nos. KJ191461- KJ191463). The sequences were 98-99% identical to each other and had the highest identity (99%) and a close phylogenetic relationship with an isolate of Bean yellow mosaic virus (BYMV; JX177278) isolated from Diuris sp. in Australia (Fig. 2). Therefore, the virus associated with mosaic disease of P. peruviana was identified as BYMV. According to the literature, Cucumber mosaic virus in India (Gupta & Singh, 1996), Colombian datura virus in Hungary (Salamon & Palkovics, 2005), Tomato spotted wilt virus in Transkei (da Graça, et al., 1985) and a tospovirus in Brazil (Eiras et al., 2012) have been found to infect P. peruviana. However, the natural occurrence of BYMV has not been previously reported. To our knowledge, this is the first report of natural occurrence of BYMV on P. peruviana.