Improving suppression of hemipteran vectors and bacterial pathogens of citrus and solanaceous plants: Advances in antisense oligonucleotide (FANA)

Authors: Hunter, Wayne; Cooper, William - Rodney; SANDOVAL, MOJICA - Aum Lifetech; McCollum, Thomas; AISHWARYA, VEENU - Aum Lifetech; PELZ-STELINSKI, KIRSTEN - University Of Florida

Submitted to: Frontiers in Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2021
Publication Date: 7/8/2021
Citation: Hunter, W.B., Cooper, W.R., Sandoval, M., Mccollum, T.G., Aishwarya, V., Pelz-Stelinski, K.S. 2021. Improving suppression of hemipteran vectors and bacterial pathogens of citrus and solanaceous plants: Advances in antisense oligonucleotide (FANA). Frontiers in Agronomy. 3:675247. https://doi.org/10.3389/fagro.2021.675247.
DOI: https://doi.org/10.3389/fagro.2021.675247

Interpretive Summary: The most serious disease in citrus trees is Huanglongbing, HLB. Tree infection results in decline health, fruit loss, and ultimately tree death. With no current cure, HLB is a threat to all citrus industries worldwide. While the majority of citrus tree infections are by the bacterium Candidatus Liberibacter asiaticus, CLas, there are related members that cause disease in potato, tomato, and other vegetables. Insects called psyllids transmit these pathogens during feeding. The Asian citrus psyllid is the primary vector in most citrus producing regions. Using genomics resources from psyllids and the bacteria, a new treatment, FANA antisense oligonucleotides was developed that can suppress bacteria replication in citrus trees, tomato, potato, and can also reduce the psyllids. Classified as a biopesticide the special properties of FANA enable safe targeting and suppression of bacteria and insects. We make the case that reduced production costs of FANA, along with data on efficacy and safety, support their consideration as viable treatments in the response to global crop pandemics, like huanglongbing in citrus that threaten global food production. Supported in-part: United States Department Agriculture, USDA, National Institute of Food and Agriculture, NIFA, Citrus Greening award #2015-70016-23028; and USDA, NIFA-award #2015-10479.

Technical Abstract: Reported is the proof-of-concept on the efficacy of FANA (2'-deoxy-2'-fluoro-arabinonucleotide) “triggers” that suppressed bacterial pathogens and psyllid vectors, in infected citrus trees, potato, and tomato plants. The pathogenic bacteria: Candidatus Liberibacter asiaticus (associated with Huanglongbing in citrus trees) and Liberibacter solanacearum (Zebra Chip disease in potato) are transmitted by psyllid vectors: the Asian citrus psyllid and the potato psyllid. Efficient delivery of FANA, which are 20-25 nucleotides long, in water applied to the soil of potted plants, showed systemic movement through trees, vegetables, and herbs and through insect tissues after fed on treated plants. Chemical modifications in FANA design enables self-delivery into cells without any carriers, provide greater stability and activity in Ribonucleic acid, RNA, suppression in bacteria and insects. Significantly reduced bacteria in psyllids also reduced psyllid transmission rates. Tomato and potato plants with suppressed bacteria titers had reduced symptom severity in leaves, and spuds, resulting in improved plant growth. These FANA oligos enable applications beyond medical and can be used to treat agricultural pathogens and pests. These advances move FANA technology closer to becoming a viable treatment in the response to crop pandemics, like huanglongbing in citrus. Supported in-part: United States Department of Agriculture, USDA, National Institute of Food and Agriculture, NIFA, Citrus Greening award #2015-70016-23028; and USDA, NIFA-award #2015-10479.