Identifikasi dan karakterisasi beberapa virus yang menginfeksi tanaman anggrek di Jawa serta induksi ketahanan sistemik tanaman anggrek dengan asam salisilat.

Abstract

Indonesia has a tremendous potency to develop orchid widely, due to the abundance of orchid germplasms. Several viruses infecting orchids were reported elsewhere. However, the presence of viruses infecting orchid in Indonesia is unknown. Thus, the aim of the researches were to identify viruses infecting orchids, its distribution in Java, its resistance response and to induced systemic resistance of susceptible orchid against Odontoglossum ringspot virus (ORSV) by using salicylic acid. Detection and identification of samples obtained from several survey locations by serological test and RT-PCR found that ORSV was detected mainly in samples from West Java (Taman anggrek Indonesia, Kebun Raya-Bogor, Gunung sindur- Bogor, Cianjur, Lembang). Cymbidium mosaic virus (CymMV) was detected mainly in central and East Java (Magelang, Malang, Surabaya). Cucumber mosaic virus (CMV), and Potyvirus were detected from all samples tested, however Tospovirus was undetectable from all samples by RT-PCR. Dual infection of ORSV and CymMV was found only in several samples from West Java. The nucleotide and amino acid sequences analysis of coat protein (CP) gene of six Java isolates of CymMV showed high homology with corresponding other 10 isolates elsewhere ranging from 95.8 to 98.8%, and 97.3 to 100%. The homology of nucleotide and amino acid sequences Java isolates of ORSV to other 11 isolates elsewhere ranging from 96.8 to 99.7% and 94.9 to 99.3%, respectively. These indicating that CymMV, ORSV, CMV and Potyvirus were present infecting orchids in Java, Indonesia. The ORSV could infect all indicator plants tested with incidence ranging from 60-100% and varied symptoms. The resistance response of 13 species of commercial orchids against ORSV showed that 61.54% of species was categorized as susceptible, and 38.46% was resistant based on type of symptoms, incubation period, disease incidence and virus accumulation. To increase the systemic resistance against ORSV infection, the susceptible orchid Dendrobium nindii was treated by using Salicylic acid (SA) on tissue culture media at concentration 1, 2, 4, 8, and 16 ppm. The SA on tissue culture media did not have any adverse effect on growth parameters and had decreased incidence, symptom expression and ORSV accumulation at concentration from 4-16 ppm. The SA treatment in plants at concentration 8-16 ppm increased total SA, and increased Phenylalanine ammonialyase (PAL) enzyme activity in compared with untreated plants. Among tested concentration, SA at concentration16 ppm was successfully able to increased D. nindii systemic resistance against ORSV with efficiency up to 93.75%. This is the first report of utilizing SA in orchid tissue culture media to increase systemic resistance against ORSV.

Indonesia mempunyai potensi luar biasa dalam mengembangkan tanaman anggrek, karena banyaknya spesifikasi plasma nutfah, namun Indonesia tertinggal dari negara lain terkait hal tersebut. Banyak anggrek asli Indonesia yang dikembangkan dan disilangkan di negara lain, kemudian diimpor kembali. Masalah yang dikhawatirkan dalam kegiatan ekspor impor bahan tanaman adalah terbawanya patogen tertentu termasuk virus. Dua virus utama yang banyak menginfeksi anggrek adalah Cymbidium mosaic virus (CymMV) dan Odontoglossum ringspot virus (ORSV), selain Cucumber mosaic virus, Potyvirus dan Tospovirus. Virus-virus tersebut telah banyak dilaporkan keberadaannya di beberapa negara, namun informasinya di Indonesia belum banyak diketahui. Untuk itu perlu dilakukan penelitian yang seksama menyangkut deteksi dan identifikasi virus-virus yang menginfeksi tanaman anggrek. Infeksi CymMV berhasil terdeteksi pada tanaman anggrek dari beberapa lokasi pertanaman di Jawa yaitu di Surabaya, Malang, Magelang, Lembang, dan Bogor (Gunung Sindur dan Kebun Raya). Virus ini menunjukkan gejala khas berupa nekrosis, klorosis dan mosaik pada daun yang terinfeksi dan gejala ini bervariasi pada tiap lokasi pengamatan. Infeksi ORSV terdeteksi melalui metode serologi pada tanaman anggrek dari Jakarta, Cianjur dan Bogor. Gejala infeksi ORSV yang ditemukan pada daun dan bunga berupa belang, mosaik, dan nekrosis. Infeksi ganda kedua virus ditemukan hanya pada sampel-sampel dari Jawa Barat (Cianjur dan Bogor).