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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Research Project #443161

Research Project: Development of Molecular Tools to Control Citrus Greening Disease

Location: Emerging Pests and Pathogens Research

Project Number: 8062-22410-007-027-A
Project Type: Cooperative Agreement

Start Date: Jul 1, 2022
End Date: Aug 31, 2024

Solutions to solving citrus green disease (also known as huanglongbing, HLB) is perhaps the most pressing need in U.S. agriculture. The HLB disease complex, the Asian Citrus Psyllid (ACP) and ‘Candidatus Liberibacter asiaticus’ (CLas) bacterium, has devastated Florida citrus production. The societal impact is massive as thousands of people have lost their jobs, farms and processors have gone bankrupt, and consumer industries inter-connected to citrus industry workers have also been negatively economically impacted. The causative microbe and its insect vector, CLas and ACP, are now found in California and Texas citrus trees. Growers have no options to block transmission of CLas by ACP, and tools are desperately needed in this area. Solutions must include protecting existing and newly planted trees, as well as delivery in an economical format suitable to each industry sector. The objective of this research project will be to identify ACP and CLas genes that regulate CLas transmission. Understanding the nature of these genes will be the foundation to new molecular strategies that block CLas transmission.

We will identify psyllid genes involved in CLas transmission using genome wide association studies. CLas is uncultivable and studies to identify genes involved in CLas transmission by ACP rely on using insects reared on CLas infected trees and comparing their organ and tissue-specific gene expression to those reared on healthy trees. Our research has shown that CLas infected trees change the expression of thousands of ACP genes, so identifying the few with a direct role in regulating CLas transmission is a major challenge. A more direct way to find ACP genes involved in transmission is to leverage the natural variation that exists in ACP for the ability to transmit CLas. The genes involved in CLas transmission can be discovered by comparing the genomes of ACP that transmit well (referred to as vectors) to the genomes of ACP that do not transmit (referred to as non-vectors). Cooperator has been involved in assembling a chromosomal length ACP genome assembly that will be used for this work. We will use high throughput genome sequencing technologies and genome wide association to identify ACP genes that regulate CLas transmission.