Introduction of a cold sensitivity‐conferring mutation into the RTA‐Bddsx hybrid system of Bactrocera dorsalis for establishment of a thermally controllable homozygous line

Abstract

BACKGROUND: For efficient control of the economically important fruit pest Bactrocera dorsalis, a hybrid system combining ricin toxicity and sex-related alternative splicing of the doublesex gene has been developed. This system exhibits the expected female-specific lethal effect; however, the transgenic females do not survive, making it difficult to raise stable homozygous lines. Since modification of ricin toxin A chain (RTA) through a single-residue change (Gly 212 > Arg 212 ) leads to cold-sensitive posttranslational repression of its toxicity, we utilized this unique property to obtain RTA-Bddsx females that survive at low temperature for line maintenance.RESULTS: In transient expression experiments using embryonic injection, two groups treated with RTAcs-derived DNA (LERQcs and RTAcs) exhibited temperature-dependent effects. The toxicity was higher at 29°C than at 18°C. The proportion of males was close to 50% at 18°C in all the tested groups except LERQcs-treated flies, which exhibited a high proportion of males (over 70%) at 29°C. The results indicate the cold-sensitive responses of RTA and further suggest a female-specific lethal effect. Subsequently, 14 putative RTAcs-Bddsx transgenic Ds-Red + G 1 males were identified, and female-specific lethal effects were observed in Ds-Red + G 2 and G 3 lines under cultivation at 29°C but not at 18°C. The male ratio can be increased to up to 95% in G 3 line 001, indicating that RTAcs functions well in B. dorsalis. CONCLUSION:The improved RTAcs-Bddsx system with conditional toxicity represents a novel and promising step toward the practical control of B. dorsalis.

Developing genetic tools to control the Oriental fruit fly: Potential approaches and target genes

“…DsRed is the most widely used fluorescent marker in B. dorsalis (Chang et al, 2016;Chen et al, 2011;Dai et al, 2021;Laohakieat et al, 2016) and constitutes the most appropriate for characterizing the tissues of transgenic lines of this pest (Chen et al, 2010). Other potential markers such as white eyes (we) and white pupae (wp) were successfully tested (Handler & McCombs, 2000;Ward et al, 2021).…”

“…However, these promoters are yet to be validated in B. dorsalis. The poly-ubiquitin (PUb) promoter has been widely used for the expression of fluorescent markers in this pest (Chen et al, 2010(Chen et al, , 2011Dai et al, 2021;Handler & Schetelig, 2020;Huang, Dai, et al, 2016).…”

Developing genetic tools to control the Oriental Fruit Fly Bactrocera dorsalis [Diptera: Tephritidae]: potential strategies and molecular tools

“…In Bactrocera dorsalis , it gave positive results on its different developmental stages and tissues (Chen et al , 2010b). It is now used by several scientists to carry out genetic engineering investigations on the Oriental fruit fly (Chen et al , 2011;Chang et al , 2016;Laohakieat et al , 2016;Dai, Huang and Chang, 2021).…”