ABSTRAK
Penelitian bertujuan menganalisis hubungan kekerabatan spesies-spesiesCercospora berdasarkan data sequence daerah Internal Transcribed Spacers (ITS)rDNA, gen elongation factor 1-α (EF), dan gen calmodulin (CAL); mengetahuilokus yang paling baik dalam memisahkan spesies-spesies Cercospora; danmenguji host specificity Cercospora spp. dengan tanaman inangnya. Padapenelitian ini telah dilakukan amplifikasi dan sequencing daerah ITS rDNA, genEF, dan gen CAL pada 14 spesies dari 23 strain Cercospora yang berasal dari tigafamili tanaman inang (Asteraceae, Cucurbitaceae, dan Solanaceae). Pohonfilogenetik dibangun menggunakan metode Neighbor-Joining, MaximumParsimony, dan Bayesian. Hasil penelitian menunjukkan bahwa pohonfilogenetik berdasarkan data sequence daerah ITS rDNA tidak dapat menjelaskanhubungan kekerabatan antarspesies pada genus Cercospora; sebagian besarCercospora (57 dari 61 OTU) berada dalam satu kelompok besar yang jarakcabangnya berimpit satu dengan lainnya. Pohon filogenetik berdasarkan datasequence gen EF dapat menjelaskan hubungan kekerabatan beberapa spesiesCercospora, walaupun sebagian spesies Cercospora (24 OTU) berada dalam satukelompok yang jarak cabangnya berimpit satu dengan lainnya. Pohon filogenetikberdasarkan data sequence gen CAL dapat menjelaskan hubungan kekerabatansebagian besar spesies Cercospora, jarak cabang terlihat lebih panjangdibandingkan pada pohon filogenetik berdasarkan data sequence gen EF,walaupun beberapa spesies Cercospora (16 OTU) belum dapat dipisahkan. Hasilanalisis filogenetik menunjukkan bahwa spesies-spesies Cercospora tidak dapatdipisahkan berdasarkan data sequence daerah ITS rDNA, akan tetapi sebagianspesies dapat dipisahkan berdasarkan data sequence gen EF dan gen CAL. Pohonfilogenetik berdasarkan data sequence gen CAL menunjukkan bahwa gen tersebutdapat digunakan untuk memisahkan spesies-spesies Cercospora lebih baikdaripada daerah ITS rDNA dan gen EF. Hasil analisis filogenetik berdasarkandata sequence multilokus menunjukkan bahwa 11 dari 14 spesies Cercosporayang digunakan dalam penelitian tidak host-specific, hanya tiga spesies yaitu C.zinniicola, C. cocciniae, dan C. mikaniicola yang spesifik terhadap inangnya.
ABSTRACT
The aims of this study were to analyze the phylogenetic relationships ofCercospora spp. based on sequence data of the internal transcribed spacer (ITS)region of rDNA, elongation factor 1-α (EF), and calmodulin (CAL) genes; todetermine the best locus in separating Cercospora species; and to investigate thehost specificity of Cercospora spp. In this study, the sequences of the ITS regionof rDNA, EF, and CAL genes of 23 strains which belong to 14 species ofCercospora from three host plants families were amplified and sequenced. Thephylogenetic trees of the Cercospora spp. were constructed by Neighbor-Joining,Maximum Parsimony, and Bayesian methods. Our result showed thatphylogenetic relationship of Cercospora at the species level could not be resolvedby ITS rDNA; most of Cercospora species (57 OTU) were grouped in one majorclade with no branch length differences among species. The EF phylogenetic tree,showed that some species of Cercospora could be separated, although 24 OTUwere grouped into one clade with no branch length differences. The CALphylogenetic tree showed that the majority of Cercospora species could beseparated with longer branch compared to the EF phylogenetic tree, althoughseveral species (16 OTU) could not be separated. The phylogenetic analysesshowed that most of Cercospora species could not be separated in the ITS rDNAtree, however those species could be separated in the EF and CAL phylogenetictrees. The results showed that CAL gene was the best locus in separatingCercospora species compared to ITS rDNA and EF gene. Molecularphylogenetic analysis from multiloci (ITS regions of rDNA, EF gene, and CALgene) revealed that 11 out of 14 species of Cercospora have no host specificity(have a wide host range) and only three species e.g., C. zinniicola, C. cocciniae,and C. mikaniicola showed host specificity. |
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