Judul: Yellows Disease on Carrots (Daucus carota L.) Associated with Phytoplasma in West Java.
Abstrak: Carrot (Daucus carota L.) is in the family Umbelliferae grown for its edible root. Carrots are widely cultivated in the highlands with loose soil type that rich of humus. It is an important vegetable plant in Indonesia and is widely consumed because it is rich in beta-carotene (A vitamin). Carrot cultivation in Indonesia was initially concentrated in West Java, such as in Cipanas (Bogor) and Lembang (Bandung), but currently it has spread to Central and East Java and outside Java due to its higher demand. One of the problems in carrot cultivation is pathogen infections that cause plant diseases and can potentially reduce yield quality and productivity. Diseases infecting carrot plants in Indonesia caused by viruses, bacteria, fungi and nematodes have been widely reported, but until now there have been no reported diseases caused by phytoplasma. Infection of phytoplasma has been reported to cause significant yield loss in some countries. Therefore, it is necessary to conduct research to determine the status of phytoplasma infecting carrot in Indonesia. Research was carried out with the following objectives: (1) Conducting observation and survey to confirm the presence of yellowing disease and leafhoppers in carrot growing areas in West Java; (2) Studying the morphological, histological and molecular properties of phytoplasmas associated with yellow disease in carrot in West Java; (3) Studying the potential of leafhoppers species Orosius argentatus and Balclutha incisa as the vector of yellow disease in carrot. Research activity began with a field survey on carrot plantations, followed by identification and characterization of phytoplasma in the laboratory and transmission assay of phytoplasma through leafhoppers in a screenhouse. During the survey in Bogor, Cianjur and Bandung, yellowing symptoms and the presence of leafhoppers were observed. Plant samples from the field were brought to the laboratory for identification of phytoplasma. The identification method consisted of microscopic observation using a transmission electron microscope (TEM), molecular detection using nested-polymerase chain reaction (nested-PCR), followed by cloning of phytoplasma DNA. Planthopper samples from the field were brought to the laboratory for identification based on morphological characters and the molecular identification of phytoplasmas associated with planthoppers. Furthermore, sequence analysis was carried out based on the 16S rRNA gene using the BLASTn, phylogenetic analysis, and in silico RFLP. The incidence of yellow disease in carrots is low, ranging from 6.22 - 7.87% in Bogor, 7.47% in Cianjur, and 5.97% in Bandung. Five species of leafhopper were found in carrot fields showing yellow symptoms in Bogor and Cianjur, i.e. B. incisa, Cicadulina bipunctata, Empoascanara indica, Exitianus indicus, O. argentatus and one species of planthopper, Sogatella furcifera. Molecular detection using nested-PCR confirmed the association of phytoplasma with yellow symptom in carrot and 4 planthopper species. Observations using TEM showed that there were abnormalities in the shape and integrity of cells in carrot leaf tissue with yellow symptoms compared to healthy plant cells. In addition, phytoplasma cells were found in the phloem tissue of symptomatic plant leaves with a rounded (spherical) but not fixed (pleomorphic) shape measuring about 0.2-0.5 m. Chlorophyl content of symptomatic leaves decreases 0.106%, but carbohydrate content as starch and reducing sugar
Keyword: analisis filogenetik, gen 16Sr RNA, insidensi penyakit, nested-PCR, wereng daun