Establish early-stage field trials for new Huanglongbing-tolerant canker-resistant transgenic scions

Establish early-stage field trials for new Huanglongbing-tolerant canker-resistant transgenic scions

Report Date: 05/10/2019
Project: 18-017   Year: 2019
Category: Horticultural & Management
Author: Zhonglin Mou
Sponsor: Citrus Research and Development Foundation

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, we have focused on the following two activities:(1) Continue treating HLB-tolerant transgenic plants under the alternating temperature conditions (25�C for 4 hours and 42�C for 4 hours). New shoots that have emerged from the previously treated trees have been tested by ELISA for CTV and by qPCR for CLas. Results have shown that both CTV and CLas do not exist in the new shoots. We have started to graft the budwoods from the new shoots onto rootstocks to generate CTV and CLas free plants, but the number is small. We are waiting for more budwoods.�(2) About 50 transgenic progeny plants that have been tested for HLB tolernace were tested by ELISA for CTV and by qPCR for CLas. Results showed that all of these plants are CTV negative and CLas postive. The majority of these plants have no HLB symptoms and three plants show mild HLB symptoms. We will plant these trees into the field in May. The field has been prepared with the help from Dr. Ed Stover in Ft Pierce USDA ARS.


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