Unveiling the seed-borne and seed transmission nature of Bhendi yellow vein mosaic virus (BYVMV) and Okra enation leaf curl virus (OELCuV) infecting bhendi ( L.).

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Begomoviruses such as bhendi yellow vein mosaic virus (Begomovirus abelmoschusflavi (BYVMV)) and okra enation leaf curl virus (Begomovirus abelsmoschusenation (OELCuV)) pose serious threats to okra (Abelmoschus esculentus) production. It is essential to comprehend how these viruses spread, in order to develop efficient disease control strategies. Initially, virus infected leaf, flower and fruit samples collected from fields were subjected to DAS-ELISA, in which the whole seed recorded highest OD value (3.10 in Coimbatore; 2.31 in Salem) from infected plants. All ELISA positive samples were subjected to PCR using specific primers for BYVMV and OELCuV for AV1 region of DNA A, none of the samples were amplified for BYVMV specific primers, whereas all the samples were amplified for OELCuV specific primers. A representative of two OELCuV PCR positive embryo samples of Thondamuthur (CBE isolate) and Edapadi (EDP) were sequenced and submitted in NCBI (Accession Numbers: CBE- PQ963865; EDP: PV126629), which showed 99-100% similarity with Tamil Nadu and Andhra Pradesh OELCuV isolates. Further to confirm seed transmission, grow-out test was carried out using two hybrid seeds namely H1 and H2 (Market seeds) under insect proof conditions. DAS-ELISA was performed for the leaf samples collected from grow-out test plants on 30th day after sowing. Out of 198 seedlings of H1, the presence of begomovirus was detected in 56 plants, whereas in hybrid H2, 12 plants were tested positive among 100 seedlings. The 198 samples of H1 and 100 samples of H2 were also subjected to PCR with specific primers for BYVMV and OELCV to detect the presence of viruses. BYVMV was not detected in any hybrid by PCR analysis. But OELCuV was found in 21.7% of H1 and 4% of H2 samples with the amplicon size of ~606bp. The seed transmission rate was higher in H1 compared to H2 hybrid. The plants which showed positive for OELCuV didn't express any pattern of symptoms and were asymptomatic. Though the seedlings were asymptomatic, they harboured the virus and could serve as inoculum source for whitefly transmission. The above findings highlight the significance of seed transmission serving as a potential source for active spread of the disease. To our knowledge, this is the first report on seed transmission of OELCuV.

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The online version contains supplementary material available at 10.1007/s13205-025-04359-6.