The project has five objectives:(1) Remove the flowering-promoting CTV and the HLB bacterial pathogen in the transgenic plants(2) Graft CTV- and HLB-free buds onto rootstocks(3) Generate a large number of vigorous and healthy citrus trees(4) Plant the citrus trees in the site secured for testing transgenic citrus for HLB responses(5) Collect the field trial data In this quarter, the following activities have been performed: (1) Took care of the transgenic plants in the greenhouse. A total of 65 transgenic plants had been prepared and molecularly characterized. These plants were regularly watered and fertilized during this quarter. They were planned to be transplanted into the field at the end of April or early May of 2020. (2) Evaluated the efficacy of the antibody against a major citrus defense protein that had recently been developed. Tissues were collected from different organs of the sweet orange ‘Hamlin’ including leaves, roots, young shoots, and bark. Conditions were optimized for extraction of total proteins from different tissues. It was found that the antibody was able to dectect the endogenous protein in the different organs. We plan to test if the antibody could work for different citrus species including rootstocks. (3) Analyzed protein levels and CLas titers in the samples collected from the transgenic plants already planted in the field. Results showed that the transgenic protein was stably expressed, but the CLas titers were undetectable in both the transgenic and control plants, indicating that these plants have not been infection. We are visually monitoring the plants and will retest CLas titers.