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 conducted: (1) Preparing and maintaining transgenic plants for field trials in the greenhouse. Transgenic plants prepared earlier for the proposed field trial were maintained in the greenhouse, waiting for transplanting. Newly produced transgenic plants expressing a regulatory gene of systemic acquired resistance were regularly watered and fertilized. A group of transgenic rootstocks were produced. We plan to graft scions onto these rootstocks in the coming year. (2) Expressing and purifying the extracellular domains of a group (10) of citrus homologs of an Arabidopsis disease resistance gene that encodes a receptor-like kinase with the extracellular domain binding nicotinamide adenine dinucleotide. It has been shown that overexpression of this receptor-like kinase increases resistance to bacterial pathogens. The citrus genome carries more than ten homologs of this receptor-like kinase. We have cloned in the last quarter the extracelllar domains of the closest ten homologs in an E. coli expression vector. In this quarter, we optimized the protein expression conditions, expressed and purified these fusion proteins from E. coli. These proeins are fused with GFP. We are currently testing the nicotinamide adenine dinucleotide-binding activities of these proteins using Monolith NT.115. The homolog(s) with nicotinamide adenine dinucleotide-binding activity will be the citrus functional homolog and will be used to generate intragenic/cisgenic citrus plants. We have generated transgenic citrus plants expressing the Arabidopsis nicotinamide adenine dinucleotide-binding receptor.s