Advances and Challenges in RNA Interference Technology for Citrus Huanglongbing Vector Control

Abstract

Citrus species, including sweet oranges, grapefruits, pomelos, and lemons, are the most widely cultivated trees and consumed fruits worldwide. In citrus orchard management, the control of Huanglongbing (HLB) disease and its insect vector Diaphorina citri (Asian citrus psyllid, ACP) represents a major global challenge. Consumers have been increasingly pushing the citrus production chain toward a more sustainable system, including stringent measures to prevent the use of chemical pesticides. In recent years, biotechnological advances have offered safe and environmentally friendly alternatives for crop production. Technologies such as RNA interference (RNAi)-mediated gene silencing have emerged as innovative tools for agricultural pest management. Here, we provide an overview of RNAi as a promising approach for ACP control and discuss the associated challenges. Despite the availability of specific silencing sequences aimed at a target gene of the insect pest, the uptake of double-stranded RNA is limited in hemipteran insects. In this context, improved delivery methods, stability maintenance, and RNAi response are considered the factors contributing to the increased effectiveness of exogenous RNAi against hemipteran pests. These approaches can serve as potential tools for efficient ACP control.

Knockdown of hexokinase in Diaphorina citri Kuwayama (Hemiptera: Liviidae) by RNAi inhibits chitin synthesis and leads to abnormal phenotypes

“…Furthermore, dsRNAs are not degraded in artificial feed solutions, indicating that they are stable and effective for screening RNAi inducers against D . citri 72 . Similar results have been observed on artificial diets incorporating V‐ATPase dsRNAs for RNAi in B .…”

“…48 Furthermore, dsRNAs are not degraded in artificial feed solutions, indicating that they are stable and effective for screening RNAi inducers against D. citri. 72 Similar results have been observed on artificial diets incorporating V-ATPase dsRNAs for RNAi in B. dorsalis, 39 N. lugens 73 and B. cockerelli 74 at 6, 24 and 96 h post-feeding, respectively. However, feeding dsRNA may be degraded by nucleases in insect saliva secretions and digestive enzymes in intestinal juice.…”

UV‐LASER adjuvant–surfactant‐facilitated delivery of mobile dsRNA to tomato plant vasculature and evidence of biological activity by gene knockdown in the potato psyllid

“…[20][21][22][23][24] Despite the success in psyllid management with chemical and biological control methods, [25][26][27] production costs have soared because of the increased use of pesticides and fertilizer treatments required to manage the disease. 25 Alternative proposed solutions to managing vectors and pathogens are double-stranded RNA (dsRNA) or peptide biopesticides delivered to the host plant phloem, 28,29 intended to reduce ACP population size and result in lowered frequencies of CLas transmission by the psyllid vector or in planta spread. 30 However, obstacles associated with foliar delivery and translaminar spread to reach the plant phloem tissues of these 'next-generation' biopesticides have impeded their implementation, which has compounded economic losses attributed to citrus greening disease.…”

“…Alternative proposed solutions to managing vectors and pathogens are double‐stranded RNA (dsRNA) or peptide biopesticides delivered to the host plant phloem, 28,29 intended to reduce ACP population size and result in lowered frequencies of CLas transmission by the psyllid vector or in planta spread 30 . However, obstacles associated with foliar delivery and translaminar spread to reach the plant phloem tissues of these ‘next‐generation’ biopesticides have impeded their implementation, which has compounded economic losses attributed to citrus greening disease 25,31,32 …”

Feature Papers in Horticulturae

“…Marques et al [12] described advances and challenges in the use of RNA interference (RNAi) technology for citrus Huanglongbing vector control. Despite the availability of specific silencing sequences aimed at a target gene of the insect pest vectors, the uptake of double-stranded RNA is limited in hemipteran insects.…”