ABSTRAKPenelitian bertujuan menganalisis hubungan kekerabatan spesies-spesies
Cercospora berdasarkan data sequence daerah Internal Transcribed Spacers (ITS)
rDNA, gen elongation factor 1-α (EF), dan gen calmodulin (CAL); mengetahui
lokus yang paling baik dalam memisahkan spesies-spesies Cercospora; dan
menguji host specificity Cercospora spp. dengan tanaman inangnya. Pada
penelitian ini telah dilakukan amplifikasi dan sequencing daerah ITS rDNA, gen
EF, dan gen CAL pada 14 spesies dari 23 strain Cercospora yang berasal dari tiga
famili tanaman inang (Asteraceae, Cucurbitaceae, dan Solanaceae). Pohon
filogenetik dibangun menggunakan metode Neighbor-Joining, Maximum
Parsimony, dan Bayesian. Hasil penelitian menunjukkan bahwa pohon
filogenetik berdasarkan data sequence daerah ITS rDNA tidak dapat menjelaskan
hubungan kekerabatan antarspesies pada genus Cercospora; sebagian besar
Cercospora (57 dari 61 OTU) berada dalam satu kelompok besar yang jarak
cabangnya berimpit satu dengan lainnya. Pohon filogenetik berdasarkan data
sequence gen EF dapat menjelaskan hubungan kekerabatan beberapa spesies
Cercospora, walaupun sebagian spesies Cercospora (24 OTU) berada dalam satu
kelompok yang jarak cabangnya berimpit satu dengan lainnya. Pohon filogenetik
berdasarkan data sequence gen CAL dapat menjelaskan hubungan kekerabatan
sebagian besar spesies Cercospora, jarak cabang terlihat lebih panjang
dibandingkan pada pohon filogenetik berdasarkan data sequence gen EF,
walaupun beberapa spesies Cercospora (16 OTU) belum dapat dipisahkan. Hasil
analisis filogenetik menunjukkan bahwa spesies-spesies Cercospora tidak dapat
dipisahkan berdasarkan data sequence daerah ITS rDNA, akan tetapi sebagian
spesies dapat dipisahkan berdasarkan data sequence gen EF dan gen CAL. Pohon
filogenetik berdasarkan data sequence gen CAL menunjukkan bahwa gen tersebut
dapat digunakan untuk memisahkan spesies-spesies Cercospora lebih baik
daripada daerah ITS rDNA dan gen EF. Hasil analisis filogenetik berdasarkan
data sequence multilokus menunjukkan bahwa 11 dari 14 spesies Cercospora
yang digunakan dalam penelitian tidak host-specific, hanya tiga spesies yaitu C.
zinniicola, C. cocciniae, dan C. mikaniicola yang spesifik terhadap inangnya.
ABSTRACTThe aims of this study were to analyze the phylogenetic relationships of
Cercospora spp. based on sequence data of the internal transcribed spacer (ITS)
region of rDNA, elongation factor 1-α (EF), and calmodulin (CAL) genes; to
determine the best locus in separating Cercospora species; and to investigate the
host specificity of Cercospora spp. In this study, the sequences of the ITS region
of rDNA, EF, and CAL genes of 23 strains which belong to 14 species of
Cercospora from three host plants families were amplified and sequenced. The
phylogenetic trees of the Cercospora spp. were constructed by Neighbor-Joining,
Maximum Parsimony, and Bayesian methods. Our result showed that
phylogenetic relationship of Cercospora at the species level could not be resolved
by ITS rDNA; most of Cercospora species (57 OTU) were grouped in one major
clade with no branch length differences among species. The EF phylogenetic tree,
showed that some species of Cercospora could be separated, although 24 OTU
were grouped into one clade with no branch length differences. The CAL
phylogenetic tree showed that the majority of Cercospora species could be
separated with longer branch compared to the EF phylogenetic tree, although
several species (16 OTU) could not be separated. The phylogenetic analyses
showed that most of Cercospora species could not be separated in the ITS rDNA
tree, however those species could be separated in the EF and CAL phylogenetic
trees. The results showed that CAL gene was the best locus in separating
Cercospora species compared to ITS rDNA and EF gene. Molecular
phylogenetic analysis from multiloci (ITS regions of rDNA, EF gene, and CAL
gene) 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.