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, due to the COVID-19 travel restriction, we were unable to travel between lab and the field trial site. This limited our work in the field. We thus focused on laboratory and greenhouse work: (1) We have prepared a new batch of transgenic plants (65 in total) that were supposed to be transplanted into the field at the end of April or early May of 2020. However, due to the COVID-19 restriction, the transplanting was postponed. These plants were maintained in the greenhouse, and were regularly watered and fertilized during this quarter. (2) Tested the antibody against a major citrus defense protein with total protein extracts from several rootstocks including Citrus macrophylla. We are particulary interested in C. macrophylla, as we can easily silence genes in this species using the established CTV-RNAi method. It was found that the antibody is able to detect the protein in the rootstocks including C. macrophylla. This would be a good tool for identifying gene targets in citrus for both gene silencing and CRISPR/Cas9-mediated gene editing. (3) Created more transgenic citrus plants expressing a new key gene in systemic acquired resistance. These transgenic plants are growing in the greenhouse and characterization is unerway.