Applications of bacteriophages in controlling rice bacterial grain rot caused by Burkholderia glumae

The study on the procedure of applicating bacteriophage (or phage) to prevent rice bacterial grain rot caused by Burkholderia glumae was conducted in the greenhouse conditions. The first experiment investigated the effect of different phage titers (i.e. 105 PFU/mL, 106 PFU/mL, 107 PFU/mL, 108 PFU/mL) in controlling bacterial grain rot of rice. The results showed that all four titers gave disease reduction with different levels, among these were the titer of 108PFU/mL expressed highest efficacy in disease reduction with the lowest percentage of infected grains compared to the rest treatments. The second experiment examined the effect of phage application times (i.e. spraying phage at 2 hours before pathogen inoculation, 2 hours before and 5 days after pathogen inoculation, and 5 days after pathogen inoculation) in suppressing bacterial grain rot disease. The results found that two treatments (i.e. one time spraying at 2 hours before pathogen inoculation, and two times spraying at 2 hours before and 5 days after pathogen inoculation) expressed high efficacy in reduction of grain rot disease through percentage of infected grains and improved yield parameter regarding rate of filled grains.

Incidence of Bacterial Grain Rot Disease, Identification, and Diversity of Burkolderia glumae in Some Rice Varieties in West Java

Penyakit busuk bulir padi oleh bakteri Burkholderia glumae perlu diwaspadai termasuk di Jawa Barat sebagai salah satu sentra produksi padi nasional. Penelitian ini bertujuan untuk menentukan insidensi penyakit, identitas dan keragaman bakteri B. glumae pada beberapa varietas padi di Provinsi Jawa Barat. Pengamatan insidensi penyakit dan pengambilan sampel dilakukan di 9 kabupaten. Bakteri diisolasi dari bulir padi yang bergejala busuk bulir kemudian dilakukan uji biokimia dan fisiologi yang meliputi uji Gram serta uji pertumbuhan pada pH 4.8, dan NaCl 2%. Variasi fenotipik diamati dari warna koloni pada medium S-PG, produksi toksofalvin, respons hipersensitivitas pada daun tembakau, dan uji patogenisitas pada tanaman padi. Primer spesifik JLBgF/JLBgR dan primer universal 16S rRNA, yaitu 27F/1492R digunakan untuk menentukan identitas bakteri secara molekuler. Insidensi penyakit di lapangan berkisar antara 0–73.3%, tertinggi di Kecamatan Dawuan (Karawang) pada var. Mekongga. Berdasarkan uji biokimia dan fisiologi diperoleh 29 isolat terkonfirmasi sebagai B. glumae. Hasil pengamatan fenotipik menunjukkan 10 isolat tergolong koloni tipe A, 19 isolat tipe B; 25 isolat menghasilkan toksoflavin; 29 isolat menimbulkan respons hipersensitivitas pada daun tembakau dan gejala hawar pada tanaman padi. Identifikasi menggunakan primer spesifik dan universal membuktikan 29 isolat adalah B. glumae. Analisis keragaman genotip menunjukkan bahwa isolat KRCH-2 (Karawang) dan INCH-6 (Indramayu) memiliki hubungan kekerabatan yang dekat dengan B. glumae asal Cina dan Amerika

Identifikasi penyebab penyakit busuk bulir bakteri pada tanaman padi (Oryza sativa) dan pengendaliannya menggunakan isolat Bacillus spp. secara in vitro

Bacterial grain rot disease in rice plant is a new disease in Indonesia. The disease can reduce rice production up to 40% in severe disease attack. Morphological and physiological identification of these pathogens can be useful as a strategy of disease control. Control of this disease using Agent Biological Control is a right step and eco-friendly. The research was conducted in July until November 2018 at Plant Quarantine Laboratory of Agricultural Quarantine Center Surabaya. Design of experiment used on pathogenic identification is descriptively and analytically while in strategy of diseases control used are Randomized Complete Design method of single factor as many as 5 treatment of Bacillus spp. such as; Ba1: Bacillus spp. isolate 1, Ba2: Bacillus spp. isolate 2, Ba3: Bacillus spp. isolate 3, Ba4: Bacillus spp. isolate 4, and Ba5: Bacillus isolate spp. 5. Research result showed that the pathogen causing bacterial grain rot in Rice is Burkholderia glumae with bacterial characteristic are Gram negative, aerobic, not fluorescent on Kings B medium, mesophyll, isotonic, can hydrolysis arginine and can produce enzyme of gelatinase and (2) Bacillus spp. Isolate which consistent to inhibiting B. glumae in vitro is Ba-1 with a mean inhibition of 17.88 mm and a variety of resistance mechanisms, namely bacteriostatic and bactericidal Isolate of Bacillus spp Keywords: Bacterial grain rot rice; Bacillus spp; Burkholderia glumae