IDENTIFIKASI JAMUR POWDERY MILDEW PADA TANAMAN MELON (Cucumis melo L.) BERDASARKAN KARAKTER MORFOLOGI DAN MOLEKULAR

Maulana Khalid Riefani, Dr. RIna Sri Kasiamdari

2011 | Tesis | S2 Biologi

Tanaman melon (Cucumis melo L.) mempunyai sifat genetik yang berbeda dan gen ketahanan yang berbeda, melon rentan infeksi jamur powdery mildew yang mempunyai perbedaan tingkat virulensi dan sensitivitas terhadap fungisida. Jamur powdery mildew menyebabkan ketahanan dan kualitas hasil melon menurun. Jamur powdery mildew berasal dari spesies Podosphaera xantii dan Golovinomyces cichoracearum yang akan beradaptasi pada tanaman inang dan melakukan perubahan morfologi, variasi sifat dan genetik. Morfologi jamur powdery mildew telah banyak diteliti, namun belum cukup menggambarkan jamur powdery mildew. Urutan nukleotida pada gen 5.8S rDNA sangat conserved dan 2 daerah Internal Transcribed Spacer (ITS) lainnya bervariasi. Identifikasi berdasarkan analisis mole kular variasi DNA di daerah ITS rDNA diharapkan dapat membantu identifikasi variasi dan menentukan hubungan filogenetik jamur powdery mildew. Tujuan penelitian ini untuk mengidentifikasi jamur powdery mildew pada tanaman melon berdasarkan karakter morfologi, karakter molekular dan mempelajari hubungan kekerabatan jamur powdery mildew yang menyerang tanaman melon. Penelitian ini dianalisis menggunakan Software Sequence Scanner, urutan nukleotida daerah ITS digabungkan dengan EditSeq dan SeqMan dalam Software Suite for Sequence Analysis DNASTAR Lasergene DM Version 3.0.25. Perbandingan antara sequence sampel menggunakan Algoritme Multiple Alignment Parameters DNA, Genetic Distance (jarak genetik) dengan Kimura-2 Parameters dan clustering (rekonstruksi pohon filogeni) dengan Neighbour Joining (NJ) pada program MEGA5 Beta, Hubungan kekerabatan antar cabang internal (Maximum Parsimony) dianalisis secara statistik dengan bootstrap 1000 (Saitou and Nei, 1987). Berdasarkan karakter morfologi adanya fibrosin bodies dalam konidia , hasil penelitian menunjukkan bahwa jamur powdery mildew yang menyerang melon adalah Podosphaera xanthii, sedangkan berdasarkan karakter mole kular jamur powdery mildew yang menyerang tanaman melon di Indonesia me mpunyai hubungan filogenetik yang sangat dekat dengan spesies Podosphaera xanthii dengan indeks similaritas (IS) 99,9-100%. Hubungan kekerabatan 12 sampel jamur powdery mildew yang menyerang tanaman melon, 1 sampel outgroup dan 20 jamur powdery mildew dari GenBank memiliki IS antara 99,98-100%, sedangkan indeks divergence antara 0,02-0,00. Pemisahan 12 sampel jamur powdery mildew pada tanaman melon di Indonesia membentuk race yang baru dari Podosphaera xanthii.

Melon (Cucumis melo L.) has a different genetic characters and different resistance genes. Melon is mainly susceptible to powdery mildew fungal infection with different levels of virulence and sensitivity to fungicides. Powdery mildew fungus causing decreased of melon qualit y and productivity. Powdery mildew fungus such as Podosphaera xantii and Golovinomyces cichoracearum adapt to the host plant and changes in their morphology, character and genetic variation. Morphology of powdery mildew fungus have been widely studied, but is needed data to describe the powdery mildew fungus. Nucleotide sequence of the 5.8S rDNA gene is very conserved while Internal Transcribed Spacer (ITS) regions more varied. Molecular analysis of DNA variation in rDNA ITS region is expected to identify variations and to determine phylogenetic relationship among powdery mildew fungus. The objective of this research was to identify the powdery mildew fungus on melon based on morphological characters, molecular characters and phylogenetic analysis of powdery mildew fungus on melon. This research was analyzed by Sequence Scanner Software and ITS region nucleotide sequence was coupled by EditSeq and SeqMan in the Sequence Analysis Software from Lasergene DNASTAR Version 3.0.25. Comparison between sequences samples was analyzed using the algorithm of DNA Multiple Alignment Parameters, Genetic Distance with Kimura-2 Parameters and Clustering (phylogeny tree reconstruction) was constructed with a Neighbor Joining (NJ) on MEGA5 Beta software. Relationship between internal branches (Maximum Parsimony) was analyzed statistically with the bootstrap 1000 (Saitou and Nei, 1987). Based on morphological characters of fibrosin bodies in the conidia, the result showed that the powdery mildew fungus on melon is Podosphaera xanthii. Moreover while based on molecular character powdery mildew fungus on melon in Indonesia has a very closed phylogenetics relationship with Podosphaera xanthii, species with similarity index (IS) 99,9 to 100%. The Phylogenetics of 12 samples powdery mildew fungus on melon, a sample of outgroup and 20 powdery mildew fungus from GenBank have high similarity (99.98 to100%). Separation of 12 samples powdery mildew fungus on melon in Indonesia show a new race of Podosphaera xanthii.

Kata Kunci : Cucumis melo L., ITS, Podosphaera xanthii, Filogenetik