Project Number: 6618-21000-013-41
Project Type: Reimbursable

Start Date: Jun 01, 2012
End Date: May 31, 2015

Objective:
To speed up the process of evaluating transformed plants for huanglungbing (HLB) resistance and identifying candidate proteins that can then be used to develop commercial citrus with HLB resistance.

Approach:
USDA-ARS in Fort Pierce has undertaken a major effort to genetically transform citrus varieties to contain genes that produce chemical defenses (antimicrobial peptides) against huanglungbing (HLB). The Citrus Research and Development Foundation is currently funding two projects to generate transformed plants, and large numbers of plants have been and continue to be produced. USDA-ARS has dedicated a greenhouse to expedite testing of these transgenics, appointed a program manager and enlisted the assistance of the Subtropical Insects Research Unit to supply infected psyllids. With respect to producing infected psyllids, infected psyllids are continually produced in each of five cages on infected citrus, and approximately 5,000 infected psyllids are produced monthly. The following is a review of the current screening program. Stage 1: A colony of HLB-infected psyllids is used to challenge the plants to psyllid infestations and HLB. Individual plants growing in conetainers are caged and infested by hot psyllids (20 adults per plant depending on the percentage of psyllids in the colony that test positive) for a week, then cages are removed and the plants are maintained in the greenhouse for two months in the midst of an open infestation of infected psyllids. Stage 2: The plants are transplanted into larger pots (D-c) and maintained in the greenhouse for six to eight months in the midst of an open infestation of infected psyllids. Stage 3: The plants are transplanted into Ruck’s pots and grown out for an additional four to six months in the midst of an open infestation of infected psyllids. The plants are then evaluated for resistance to HLB, which requires growth measurements and real-time polymerase chain reaction assays (RT-PCR) analyses.