<p>ABSTRAK</p><p>Penyakit layu bakteri yang disebabkan oleh Ralstonia solanacearummerupakan kendala utama budidaya jahe, yang menyebabkan kehilanganhasil lebih dari 90%. Upaya pengendalian yang dilakukan belum optimal,karena tidak tersedianya varietas jahe tahan patogen tersebut. Kendalautama untuk memperoleh varietas jahe yang tahan adalah terbatasnyasumber gen ketahanan dan adanya hambatan fisiologis pada prosespersilangan jahe karena sifat inkompatibilitas sendiri, serta rendahnyafertilitas polen menyebabkan persilangan jahe secara konvensional sulitdilakukan. Seleksi in vitro menggunakan medium selektif yangmengandung filtrat patogen merupakan salah satu metode inkonvensionaluntuk meningkatkan ketahanan tanaman. Penelitian ini dilakukan diLaboratorium Kultur Jaringan dan Laboratorium Penyakit Balai PenelitianTanaman Obat dan Aromatik (Balittro) dari bulan April 2008 sa,mpaiOktober 2008 dengan tujuan untuk mengetahui tingkat ketahanan jahepada stadia kalus terhadap filtrat R. solanacearum dan memperolehkonsentrasi filtrat yang tepat sehingga diperoleh varian kalus baru tahanterhadap filtrat patogen tersebut. Kalus embriogenik jahe putih besar asaleksplan meristem berumur 8 minggu, diseleksi selama 3 minggu di dalammedium proliferasi (MS + 3% manitol tanpa zat pengatur tumbuh),mengandung filtrat R. solanacearum. Seleksi bertingkat dilakukan denganmengaplikasikan filtrat R. solanacearum pada konsentrasi berbeda, yaitu:0; 0,1; 0,2; 0,3; 0,4; 0,5; 1; 2; 3; 4; dan 5%, pada tahap pertama. Padaseleksi tahap kedua, kalus disubkultur ke dalam media yang sama dengankonsentrasi filtrat dinaikkan 10 kali dari konsentrasi awal. Penelitianmenggunakan rancangan acak lengkap, diulang 10 kali. Hasil penelitianmemperlihatkan penggunaan filtrat R. solanacearum di dalam mediumkultur in vitro jahe pada seleksi tahap pertama dan kedua menyebabkanterjadinya perubahan warna kalus dari putih kekuningan menjadi kuningkecoklatan dan coklat kehitaman. Berat dan diameter kalus, jumlahembrio globular serta embrio torpedo berkurang secara nyata setelahperlakuan filtrat, pada seleksi tahap pertama maupun kedua seiring denganbertambah tingginya konsentrasi filtrat. Konsentrasi filtrat R.solanacearum yang mampu menginduksi dan menyeleksi kalusembriogenik berkisar antara 0,3 - 2% dari volume medium seleksi kaluspada seleksi tahap 1 dan 3 - 20% pada seleksi tahap 2.</p><p>Kata kunci : Zingiber officinale Rosc., kalus, seleksi in vitro,ketahanan, filtrat R. solanacearum</p><p>ABSTRACT</p><p>The use of R. solanacearum filtrate in callus selection ofin vitro for ginger resistance to bacterial wilt disease</p><p>Bacterial wilt disease caused by Ralstonia solanacearum is the mainconstraint in ginger cultivation. It often causes significant yield loss ofmore than 90%. Various controlling techniques are not able to overcomethe disease, due to unavailability of resistant ginger cultivar. Limitation inobtaining resistant ginger variety is caused by several factors includingthe lack of resistant gene, physiological barrier due to the selfincompatibility, and low pollen fertility, these cause difficulty inconventional cross breeding. Therefore, genetic variability enhancementhas to be carried out unconventionally, to obtain ginger variety resistant tothe disease. In vitro selection using a selective medium containing filtrateof the pathogen is one of the potential unconventional method to improveginger plant resistance. The study was conducted at Meristem Culture andPlant Disease Laboratories of IMACRI from April to October 2008 aimingat determining the level of resistant ginger on stage of calli to the filtrateof R. solanacearum and to obtain an appropriate concentration of thefiltrate which induced calli variants resistant to the filtrate. Large whiteginger embryogenic calli meristems of 8 weeks old were selected for 3weeks in proliferation medium (MS + 3% mannitol without growthregulators), containing filtrate of R. solanacearum. For that purpose, twostages of in vitro selection were performed by applying differentconcentrations of R. solanacearum filtrate e.g; 0; 0.1; 0.2; 0.3; 0.4; 0.5; 1;2; 3; 4; and 5% at the first stage selection. Those concentrations were thenmultiplied 10 times at the second stage selection. Experiments werearranged in completely randomized design with 10 replicates. Resultsshowed that the use of R. solanacearum filtrate as selection agent in gingerin vitro culture medium has caused changes in calli color from theyellowish white into the blackish brown. In addition, increase of R.solanacearum filtrate concentration at the 1 st and 2 nd selection stages wasin line with the decreased of the calli weight and diameter, as well asnumber of globular and torpedo embryo. The concentration of R.solanacearum filtrate applied at 0.3 to 2% in the 1 st selection followed by3 to 20% in the 2 nd selection induced resistant embryogenic calli of ginger.</p><p>Key words : Zingiber officinale Rosc., calli, in vitro selection,resistance, R. solanacearum filtrate</p>
Unravelling the Differential Expression of Potential microRNAs in Bacterial Wilt-resistant and Susceptible Ginger Species
