KARAKTER MORFOLOGI DAN MOLEKULER ISOLAT Phytophthora palmivora ASAL KELAPA DAN KAKAO

ABSTRAK Phytophthora palmivora merupakan patogen penyebab penyakit gugur buah pada tanaman kelapa dan busuk buah pada tanaman kakao. Penelitian ini bertujuan untuk membedakan isolat P. palmivora asal kelapa dan asal kakao berdasarkan karakter morfologi dan molekuler. Pengambilan sampel penyakit gugur buah kelapa dan busuk buah kakao dilakukan di Kabupaten Banyuwangi dan Jember, Jawa Timur, Kabupaten Minahasa dan Bolaang Mongondow, Sulawesi Utara, dan Kabupaten Gorontalo, Gorontalo. Analisis morfologi, ekstraksi DNA dan amplifikasi DNA dengan PCR dilakukan di Laboratorium Mikologi dan Laboratorium Virologi, Departemen Proteksi Tanaman, Faperta IPB. Analisis perunutan DNA dilakukan di Laboratorium Biologi Molekuler, Balai Besar Bioteknologi dan Sumberdaya Genetik dan Laboratorium Bioteknologi, LIPI Serpong. Penelitian dilaksanakan pada bulan April 2005 sampai Februari 2007. Berdasarkan karakter morfologi seperti diameter koloni, panjang dan lebar sporangium, tipe koloni, bentuk sporangium, per- bandingan panjang dan lebar sporangium serta runutan DNA ruas ITS menunjukkan bahwa keduapuluh-dua koleksi isolat yang menunjukkan gejala penyakit gugur buah kelapa dan busuk buah kakao adalah P. palmivora. Isolat P. palmivora asal kelapa berbeda dengan isolat P. palmivora asal kakao berdasarkan diameter koloni, panjang dan lebar sporangium serta runutan DNA ruas ITS. Duapuluh-dua isolat P. palmivora asal kelapa dan asal kakao mempunyai sporangium yang mudah lepas dari sporangiospora (caducous), pedikel yang pendek dan papila serta bervariasi dalam bentuk dan ukuran sporangium. Bentuk sporangium terdiri dari 4 tipe yaitu ovoid, limoniform, obturbinate, dan obpyriform. Ukuran sporangium berkisar antara 40 – 62 µm panjang dan 28 – 43 µm lebar. Isolat P. palmivora memiliki tipe koloni rosaceous, stelate dan cottony. Rata-rata diameter koloni isolat asal kelapa 54.8 cm lebih tinggi dari isolat asal kakao 43,4 cm. Hasil perunutan DNA hasil PCR menunjukkan adanya keragaman genetik antar isolat asal kelapa dan kakao di Indonesia. Isolat asal kakao berbeda dengan isolat asal kelapa berdasarkan perunutan DNA ruas ITS. Isolat P. palmivora asal kelapa dan kakao dari Indonesia tidak berada dalam satu kelompok dengan isolat yang berasal dari Thailand, Taiwan, Korea, Puerto Rico, Ghana, dan Cameron. Kata kunci : Kelapa, Cocos nucifera, kakao, Theobroma cacao, penyakit, P. palmivora, morfologi, molekuler, keragaman, runutan DNA-ITS, Jawa Timur, Sulawesi Utara, Gorontalo, Jawa Barat ABSTRACT Morphology  and  molecular  characteristics  of  P. palmivora isolates from coconut and cacao Phytophthora palmivora, is the pathogen of coconut nutfall and cacao black pod diseases. This study was conducted to differentiate the isolates of P. palmivora from coconut and those from cacao fruit based on morphology and molecular characteristics. Samples of nutfall of coconut and black pod of cacao were collected from Banyuwangi and Jember Districts, East Java, Minahasa and Bolaang Mongondow Districts, North Sulawesi, and Gorontalo District, Gorontalo. Morphological analysis, DNA extraction and amplification of PCR-DNA were conducted in Micology Laboratorium and Virology Laboratorium, Plant Protection Division, Faperta IPB. Sequencing DNA analysis was conducted in Molecular Biology Laboratory, Balai Besar Bioteknologi dan Sumberdaya Genetik and Biotechnology Laboratory LIPI Serpong. This research was conducted from April 2005 to February 2007. Comparative morphological evaluated i.e. diameter of colony, length and width of sporangium, l/w ratio, type of colony and sequence Internal Transcribed Sequence (ITS)- DNA showed that all isolates of Phytophthora isolated from coconut and cacao  in  Indonesia  were  Phytophthora  palmivora.  Morphology characteristics of pathogen isolates from cacao were smaller and significantly different in length, width, length/width ratio of sporangium and diameter of colony compared to coconut’s isolates. Sporangia of 22 isolates were caducous with short pedicel, but were variable in shape and size. The culture produced ovoid, limoniform, obturbinate, dan obpyriform sporangia, average 40-62 µm in length and 28-43 µm in width. The colony types were stelate, cottony and rossaceous with average diameter of coconut isolates 54.8 cm and cacao isolates 43.4 cm. Specific fragment of 900 bp was successfully amplify from coconut and cacao infected by P. palmivora. The DNA sequence analysis of the nuclear ribosomal internal transcribed spacer (ITS) region showed that the coconut isolates were not in the same cluster with the cacao isolates. Based on sequence analysis, the P. palmivora isolates from Indonesia showed different cluster from those of Taiwan, Ghana, Puerto Rico and Costa Rica isolates. Key words :  Coconut, Cocos nucifera, cacao, Theobroma cacao, diseases, P. palmivora, diversity, morphology, molecular, sequencing  ITS-DNA,  East  Java,  North  Sulawesi, Gorontalo, West Jav