KARAKTER MORFOLOGI DAN MOLEKULER ISOLAT Phytophthora palmivora ASAL KELAPA DAN KAKAO - HIASINTA FJ MOTULO; MEITY S-SINAGA; GEDE SUASTIKA; HAJRIAL ASWIDINNOOR; ALEX HARTANA (Pusat Penelitian dan Pengembangan Perkebunan, 2007)
ABSTRAKPhytophthora palmivora merupakan patogen penyebab penyakitgugur buah pada tanaman kelapa dan busuk buah pada tanaman kakao.Penelitian ini bertujuan untuk membedakan isolat P. palmivora asal kelapadan asal kakao berdasarkan karakter morfologi dan molekuler.Pengambilan sampel penyakit gugur buah kelapa dan busuk buah kakaodilakukan di Kabupaten Banyuwangi dan Jember, Jawa Timur, KabupatenMinahasa dan Bolaang Mongondow, Sulawesi Utara, dan KabupatenGorontalo, Gorontalo. Analisis morfologi, ekstraksi DNA dan amplifikasiDNA dengan PCR dilakukan di Laboratorium Mikologi dan LaboratoriumVirologi, Departemen Proteksi Tanaman, Faperta IPB. Analisis perunutanDNA dilakukan di Laboratorium Biologi Molekuler, Balai BesarBioteknologi dan Sumberdaya Genetik dan Laboratorium Bioteknologi,LIPI Serpong. Penelitian dilaksanakan pada bulan April 2005 sampaiFebruari 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 ITSmenunjukkan bahwa keduapuluh-dua koleksi isolat yang menunjukkangejala 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 lebarsporangium serta runutan DNA ruas ITS. Duapuluh-dua isolat P.palmivora asal kelapa dan asal kakao mempunyai sporangium yang mudahlepas dari sporangiospora (caducous), pedikel yang pendek dan papilaserta bervariasi dalam bentuk dan ukuran sporangium. Bentuk sporangiumterdiri dari 4 tipe yaitu ovoid, limoniform, obturbinate, dan obpyriform.Ukuran sporangium berkisar antara 40 – 62 µm panjang dan 28 – 43 µmlebar. Isolat P. palmivora memiliki tipe koloni rosaceous, stelate dancottony. Rata-rata diameter koloni isolat asal kelapa 54.8 cm lebih tinggidari isolat asal kakao 43,4 cm. Hasil perunutan DNA hasil PCRmenunjukkan adanya keragaman genetik antar isolat asal kelapa dan kakaodi Indonesia. Isolat asal kakao berbeda dengan isolat asal kelapaberdasarkan perunutan DNA ruas ITS. Isolat P. palmivora asal kelapa dankakao dari Indonesia tidak berada dalam satu kelompok dengan isolatyang berasal dari Thailand, Taiwan, Korea, Puerto Rico, Ghana, danCameron.Kata kunci : Kelapa, Cocos nucifera, kakao, Theobroma cacao, penyakit,P. palmivora, morfologi, molekuler, keragaman, runutanDNA-ITS, Jawa Timur, Sulawesi Utara, Gorontalo, JawaBaratABSTRACTMorphology and molecular characteristics of P.palmivora isolates from coconut and cacaoPhytophthora palmivora, is the pathogen of coconut nutfall andcacao black pod diseases. This study was conducted to differentiate theisolates of P. palmivora from coconut and those from cacao fruit based onmorphology and molecular characteristics. Samples of nutfall of coconutand black pod of cacao were collected from Banyuwangi and JemberDistricts, East Java, Minahasa and Bolaang Mongondow Districts, NorthSulawesi, and Gorontalo District, Gorontalo. Morphological analysis,DNA extraction and amplification of PCR-DNA were conducted inMicology Laboratorium and Virology Laboratorium, Plant ProtectionDivision, Faperta IPB. Sequencing DNA analysis was conducted inMolecular Biology Laboratory, Balai Besar Bioteknologi dan SumberdayaGenetik and Biotechnology Laboratory LIPI Serpong. This research wasconducted from April 2005 to February 2007. Comparative morphologicalevaluated i.e. diameter of colony, length and width of sporangium, l/wratio, type of colony and sequence Internal Transcribed Sequence (ITS)-DNA showed that all isolates of Phytophthora isolated from coconut andcacao in Indonesia were Phytophthora palmivora. Morphologycharacteristics of pathogen isolates from cacao were smaller andsignificantly different in length, width, length/width ratio ofsporangium and diameter of colony compared to coconut’s isolates.Sporangia of 22 isolates were caducous with short pedicel, but werevariable in shape and size. The culture produced ovoid, limoniform,obturbinate, dan obpyriform sporangia, average 40-62 µm in length and28-43 µm in width. The colony types were stelate, cottony and rossaceouswith average diameter of coconut isolates 54.8 cm and cacao isolates 43.4cm. Specific fragment of 900 bp was successfully amplify from coconutand cacao infected by P. palmivora. The DNA sequence analysis of thenuclear ribosomal internal transcribed spacer (ITS) region showed that thecoconut isolates were not in the same cluster with the cacao isolates. Basedon sequence analysis, the P. palmivora isolates from Indonesia showeddifferent cluster from those of Taiwan, Ghana, Puerto Rico and Costa Ricaisolates.Key words : Coconut, Cocos nucifera, cacao, Theobroma cacao,diseases, P. palmivora, diversity, morphology, molecular,sequencing ITS-DNA, East Java, North Sulawesi,Gorontalo, West Jav