The Diagnosis on Huanglongbing Disease of Citrus

It was first reported that the colloidal gold labeled monoclonal antibody technique was used to diagnose Huanglongbing disease of citrus. The isolated cultural pathogen organism was used as antigen in preparing monoclonal antibody, and labeled with colloidal gold. The handle section of leaf stalk or leaf vein from citrus was stained with the immune gold silver method. The result was observed under optical microscope. The phloem sieve element was stained in black or brown black colo r, and the healthy tissue re-mained nonstained. It was more reliable and mo re rapid to use this method for diagnosis on H uanglongbing disease of citrus. The indirect immunofluorescent technique used for diagnosis of Huanglongbing disease of citrus was studied as well under laser confocal scanning microscope. The section of leaf stalk was first treated with mo noclonal antibody, and then stained with FITC coupled goat antimouse globulin. The re-sult demonstrated that the phloem sieve element with the disease was stained with specific white fluorescent and the healthy tissue rem ained nonstained. The image measurement software was used to analy ze the fluorescent density. The polymerase chain reaction was developed for detecting the sequence of 16sDNA gene of Asian strain from India. A 1160bp specific amplification products was obtained in PCR reaction using DNA from Huang long bing disease of citrus as templet.