| dc.description.abstract | Citrus is an important horticultural commodity with high economic value in many countries. Huanglongbing disease, or in Indonesia known as citrus vein phloem degeneration caused by Liberobacter asiaticus bacterium, is a major factor limiting citrus production in many Asian countries. The disease detection and diagnosis solely based on its symptom is sometimes not reliable since it resembles to those caused by nutrient deficiencies. Detection using polymerase chain reaction is an accurate technique for many plant pathogens including the huanglongbing causal agent. The research objectives are to observe huanglongbing disease of citrus, based on external and internal symptoms, in Bogor and to optimize PCR technique for detection of the pathogen. The disease identification and detection based on the external symptom showed that there was less specific character which correlated with pathogen presence in the sample. Symptom of the infected plants is leaf discoloration and deformation. The leaves showing symptoms of chlorosis, are smaller and more lancet than leaves without chlorosis symptoms. The results of detection based on internal symptom showed as starch accumulation in phloem are consistent with that of PCR. The optimization of detection using PCR showed that the most effective and efficient extraction method to obtain DNA template was a modification of Dellaporta et al. (1986) with extraction buffer concentration at 2 times. After 2 weeks period of storage treatment at 4 oC, Huanglongbing disease can still be detected by PCR, but its DNA bands showed inconsistency among three replications. The most optimum two weeks sample preservation is at 4 oC, whereas preservation with CTAB buffer still maintain the sample to yield DNA template adequately for PCR | en |
