Judul: Potensi Bakteri Endofit Asal Wortel Sebagai Agens Pengendali Penyakit Busuk Lunak Pectobacterium carotovorum subsp. carotovorum
Abstrak: Busuk lunak merupakan salah satu penyakit penting pada wortel yang disebabkan oleh bakteri Pectobacterium carotovorum subsp. carotovorum (Syn. Erwinia carotovora subsp. carotovora). Patogen ini memiliki kemampuan untuk menyebabkan kerusakan serius baik di lapangan maupun penyimpanan. Gejala busuk lunak pada umbi wortel yaitu jaringan menjadi lunak, basah, berlendir, berwarna kecoklatan atau krem, dan mengeluarkan lendir. Salah satu alternatif pengendalikan penyakit busuk lunak yaitu menggunakan agens hayati seperti bakteri endofit. Penelitian ini bertujuan mendapatkan bakteri endofit asal wortel yang memiliki potensi dalam menekan perkembangan penyakit busuk lunak Pectobacterium carotovorum subsp. carotovorum (Pcc) secara in vitro dan in vivo serta mengidentifikasi isolat bakteri yang potensial tersebut secara molekuler. Identifikasi bakteri Pcc secara molekuler dilakukan dengan teknik PCR menggunakan primer spesifik Ec001. Pengujian in vitro dilakukan dengan metode plate diffusion. Pengujian in vivo dilakukan pada wortel dan menghitung persentase kejadian penyakit serta persentase penghambatan pertumbuhan patogennya. Percobaan dilakukan dengan menggunakan rancangan acak lengkap (RAL). Identifikasi bakteri endofit secara molekuler dilakukan dengan teknik PCR menggunakan primer universal gen16S rRNA. Sebanyak 292 isolat telah berhasil diisolasi dan berdasarkan hasil seleksi diperoleh empat isolat yang berpotensi menghambat pertumbuhan patogen secara in vitro. Dua isolat dengan persentase penghambatan penyakit busuk lunak tertinggi secara in vivo adalah CRO 83 dan CRO 24 dengan persentase penghambatan sebesar 88,09% dan 40,47% dan persentase kejadian penyakit berturut-turut sebesar 12,50% dan 4,16%. Hasil identifikasi molekuler didapatkan bahwa kedua isolat tersebut adalah Enterobacter asburiae dan Serratia marcescens, Soft rot is one of the important diseases of carrots caused by Pectobacterium carotovorum subsp. carotovorum (Syn. Erwinia carotovora subsp. carotovora). This pathogen has the ability to cause serious damage both in the field and in storage. The symptoms of soft rot in carrot tubers are that the tissue becomes soft, wet, rotted, slimy, the surface of the tuber is brownish or cream color, and emits rotten stench. One of the alternatives methods to control this disease is the application of endophytic bacteria as biological control agents. This study aims to obtain endophytic bacteria from carrots that have the ability to suppress the development of soft rot disease caused by P. carotovorum subsp. carotovorum and to identify the pathogens and the potential biocontrol bacterial isolates molecularly. Molecular identification of Pcc was conducted by PCR technique using specific primers Ec001. In vitro testing was carried out using the plate diffusion method. In vivo testing was conducted on carrot tubers and calculating the percentage of disease incidence and the percentage of growth inhibition of pathogen. The experiment wasperformed following a complete randomized design (RAL). Identification of endophytic bacteria molecularly was carried out by PCR technique using universal primer gen 16S rRNA. A total of 292 endophytic bacteria isolates have successfully been isolated from healthy carrot tubers. Based on in vitro selection results, four isolates were had the best capability of inhibiting pathogen growth. Two isolates with the best performance in vivo were CRO 83 and CRO 24 with inhibition percentages of 88,09% and 40,47% and disease incidence percentages of 12,50% and 4,16%, respectively. The results of molecular identification showed that the two isolates were Enterobacter asburiae (CRO 83) and Serratia marcescens
Keyword: Daucus carota, Enterobacter, Erwinia carotovora subsp. carotovora, Pengendali hayati, Serratia