Knockdown of the Trehalose-6-Phosphate Synthase Gene Using RNA Interference Inhibits Synthesis of Trehalose and Increases Lethality Rate in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae)

Abstract

Diaphorina citri Kuwayama is the vector of citrus “huanglongbing”, a citrus disease which poses a significant threat to the global citrus industry. Trehalose-6-phosphate synthase (TPS) plays an important role in the regulation of trehalose levels of insects, while its functions in D. citri are unclear. In this study, full-length cDNA sequences of the TPS gene from D. citri (DcTPS) were cloned and its expression patterns at various developmental stages were investigated. The results indicated that DcTPS mRNA was expressed at each developmental stage and the highest DcTPS expression was found in the fifth-instar nymphs of D. citri. Additionally, mortality and deformity of D. citri were observed after 24 and 48 h by feeding with three different dsRNA concentrations (20, 100 and 500 ng/μL). The results indicated that DcTPS expression was declined, and mortality and malformation in nymphs were increased via feeding with dsDcTPS. Moreover, the enzyme and trehalose content were decreased, while the content of glucose was significantly higher than that of untreated (control) individuals. This suggests that DcTPS might be vital for the growth and development of D. citri and further studies of the genes should be related to molting and metabolism for controlling D. citri.

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

“…The transformant method involves the generation of a transgenic plant (genetically modified organism, GMO) harboring a construct to produce dsRNA targeting the insect mRNA. Meanwhile, the non-transformant delivery methods are GMO-free and include micro-injection of dsRNA directly into the hemolymph [37], topical application on insect body [38,39], soaking insects into a dsRNA solution [40,41], feeding insects with artificial diets containing dsRNA molecules [42][43][44], and feeding insect with plants treated with a dsRNA solution through drenching or trunk injection [45]. Despite the introduction of several dsRNA molecules, however, only those delivery methods that result in insect topical absorption and/or acquisition via feeding are applicable for ACP management in citrus orchards (Table 1).…”

“…RNAi-mediated ACP control has also been tested using feeding assays. Through the ingestion of an artificial diet, several genes including cathepsin D, chitin synthase, inhibitor of apoptosis [55], boule [42], trehalose-6-phosphate synthase [43], and odorant-binding 7 [44], in ACP were silences, leading to a lethal phenotype and/or an abnormal behavioral response. Furthermore, knockdown of the arginine kinase and superoxide dismutase genes through feeding and iPS reduced the ACP adult survival rate [26].…”

Optimizing Efficient RNAi-Mediated Control of Hemipteran Pests (Psyllids, Leafhoppers, Whitefly): Modified Pyrimidines in dsRNA Triggers

“…Soluble Trehalase-Research has shown that Trehalase has critical functions in hemipteran development and survival [142,[155][156][157]. When Trehalase is suppressed then the synthesis of Trehalose is reduced and there is an increase in psyllid mortality [112], with similar reports in planthoppers [158] and other invertebrates [159,160]. Trehalose is the main blood sugar of insects, and the enzyme trehalase is involved in energy metabolism and regulates trehalose levels in cells.…”

“…The earliest RNAi in the Asian citrus psyllid and the glassy-winged sharpshooter sequenced the Arginine kinase , to produce AK- dsRNA’s that were evaluated between species showing RNAi specificity [ 107 ], following studies validated the effects of AK, actin, SOD, Trehalase and cactin -dsRNA’s [ 34 , 50 , 87 , 108 , 109 , 110 , 111 ]. A partial list of genes targeted in other RNAi studies in psyllid have reported knockdown of: trehalase and trehalose-6-phosphate synthase gene [ 112 ]; Superoxide dismutase [ 113 ]; the abnormal normal wing disc gene [ 114 ]; injection and feeding of CYP-dsRNA’s to suppress insecticide resistance [ 115 , 116 ]; suppression of two glutathione S-transferase genes, DcGSTe2 and DcGSTd1, increased psyllid susceptibility to pesticides [ 117 ]; and carboxylesterases to increase nymph mortality [ 118 ]. The strong RNAi response to dsRNA triggers shows that RNAi has the potential to be used to manage psyllid pests.…”

Regulation of a Trehalose-Specific Facilitated Transporter (TRET) by Insulin and Adipokinetic Hormone in Rhodnius prolixus, a Vector of Chagas Disease

“…Identifying that trehalose increases in the ovary after a blood meal is the first indication that its synthesis by the fat body may be necessary for the accumulation of carbohydrates by the ovaries during this rapid developmental phase of the oocytes, i.e., vitellogenesis ( Valle, 1993 ; Roy et al, 2018 ). TPS has previously been detected and/or quantified in fat bodies of several species ( Cui and Xia, 2009 ; Xu et al, 2009 ; Chen et al, 2010 ; Tang et al, 2010 , 2018 ; Xiong et al, 2019 ; Liu et al, 2020 ) including R. prolixus females, where a transcriptome analysis reveals an up-regulation of this enzyme in the fat body of fed females ( Leyria et al, 2020b ). Interestingly, in R. prolixus , the concentration of trehalose in the fat body and hemolymph is lower than that found in other non-hematophagous species ( Oda et al, 2000 ; Singtripop et al, 2002 ; Moriwaki et al, 2003 ; Michitsch and Steele, 2008 ; Huang et al, 2012 ; Kim and Hong, 2015 ; Kh and Keshan, 2019 ) and, more importantly, it is also lower compared to that found in R. prolixus males ( Mariano et al, 2009 ).…”