ABSTRAKInfeksi virus di pertanaman bawang merah dapat menimbulkan gejala mosaik pada daun dan tanaman kerdil. Identitas virus penyebab penyakit perlu diketahui untuk menentukan pengelolaan penyakit yang tepat sasaran. Penelitian ini bertujuan mendeteksi virus terbawa umbi benih bawang merah. Deteksi virus dilakukan dengan uji tumbuh umbi, penularan mekanis, dan pengamatan morfologi partikel virus dengan mikroskop elektron. Bibit bergejala hasil uji tumbuh digunakan sebagai inokulum penularan mekanis. Penularan mekanis dilakukan pada tanaman bawang merah kultivar Biru Bantul, Chenopodium amaranticolor, dan Nicotiana tabacum. Inokulasi mekanis mengakibatkan munculnya gejala mosaik dan kerdil pada bawang merah, nekrosis lokal pada C. amaranticolor, dan tidak ada gejala pada N. tabacum. Hasil pengamatan mikroskop elektron menunjukkan 2 jenis partikel virus, yaitu filamen berukuran 650 nm dan filamen lentur berukuran 800 nm berturut-turut dari tanaman bergejala mosaik dan kerdil. Hal tersebut mengindikasikan ada 2 jenis virus yang terbawa benih bawang merah, yaitu diduga sebagai Shallot latent carlavirus (SLV) dan Onion yellow dwarf potyvirus (OYDV). Identitas virus perlu dikonfirmasi lebih lanjut berdasarkan analisis sikuen nukleotida dan proteinnya.
Kata kunci: mikroskop elektron, penularan mekanis, uji tumbuh umbi
ABTRACTVirus infection on shallots may cause mosaic of leaves and plant dwarf. It is very important to know the identity of the virus as a requirement in determining viral disease management strategy. The research is subjected to identify seed-transmitted viruses from shallot bulbs. Detection of virus from bulb was conducted by growing on test, followed by mechanical inoculation on shallot cultivar Biru Bantul, Chenopodium amaranticolor, and Nicotiana tabacum and morphological observation of virus particle by electron microscope. About 2 weeks after inoculation symptoms was observed, i.e. mosaic and dwarf on shallot cultivar Biru Bantul, local necrotic on C. amaranticolor, but symptomless on N. tabacum. Filamentous particles of 650 nm and 800 nm in length was observed under electron microscope from plants with mosaic and dwarfing symptom, respectively. This indicated the presence of 2 different seed-transmitted viruses on infected shallots. Two species of shallot viruses, i.e. Shallot latent carlavirus (SLV) and Onion yellow dwarf potyvirus (OYDV) was most likely the main seedborne viruses on shallot bulb. Identification based on nucleic acid and protein sequence analysis is necessary for further confirmation