Using Citrus Tristeza Virus to Dissect Plant Response to Identify Citrus Targets for CRISPR Modification
Posted August 2025
Researchers: Choaa El Mohtar, Zhonglin Mou, Nian Wang, Amit Levy, Manjul Dutt
Contact: Choaa El Mohtar, UF/IFAS CREC mohtarc@ufl.edu
Summary:
A sustainable environmentally friendly solution to manage huanglongbing (HLB) is the development of tolerant or resistant citrus plants. However, elite commercial scions lack tolerance to HLB. Tolerance/resistance either needs to be engineered via biotechnology or introgressed from wild relatives. Introgressing from wild relatives into elite commercial lines is an extremely slow process because of the long juvenile phase and the need for back crosses. Engineering resistance via biotechnology is much faster and could be done directly into elite commercial scions. CRISPR, which enables targeted gene editing like natural mutations, is the technology of choice. However, there is a need to understand why all commercial citrus scions are susceptible, whereas some wild citrus and relatives are resistant/tolerant. For this purpose, we engineered 70 citrus tristeza vectors (CTV) vectors to overexpress or downregulate citrus genes related to plant defense, susceptibility genes, callose deposition, and reactive oxygen species. Among the sweet orange seedlings infected with the different CTV vectors screened, we identified two genes that upon downregulation induce tolerance to HLB. We are continuing to screen all target genes and our collaborators are working on modifying these genes via CRISPR technology.
Take Home Message:
- CTV is a faster tool to identify therapeutics against HLB than transgenic or CRISPR strategies.
- Manipulation of a single citrus gene in commercial scions could induce tolerance to HLB.
- The identified target will be used for CRISPR modification to generate tolerant citrus genotypes.
