Topical Spray of dsRNA Induces Mortality and Inhibits Chilli Leaf Curl Virus Transmission by Bemisia tabaci Asia II 1

Abstract

Chilli leaf curl virus (ChiLCV; genus: Begomovirus), transmitted by Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in a persistent-circulative manner, is a major constraint in chilli production. The present study demonstrates for the first time that a topical spray of naked double-stranded RNA (dsRNA) on chilli plants causes mortality and inability to acquire and transmit ChiLCV in B. tabaci. dsRNA targeting heat shock protein 70 (hsp70) and fasciclin 2 (fas2) of B. tabaci Asia II 1 was first assessed under controlled conditions through oral delivery. Hsp70 and fas2 dsRNA resulted in up to 82.22% and 72% mortality of B. tabaci and around 12.4- and 8.5-fold decreases in mRNA levels, respectively, 24 h post-ingestion. ChiLCV copies in hsp70 dsRNA-fed B. tabaci steadily decreased with an increase in dsRNA concentration and were undetectable at a higher concentration of dsRNA. However, ChiLCV copies significantly increased in fas2 dsRNA-fed B. tabaci. Transmission of ChiLCV by B. tabaci was completely inhibited post-24 h feeding on hsp70 dsRNA at 3 μg/mL. Naked hsp70 dsRNA was topically sprayed on ChiLCV-infected chilli plants like an insecticide. 67.77% mortality of B. tabaci, 4.6-fold downregulation of hsp70 mRNA, and 1.34 × 1015-fold decreased ChiLCV copies in B. tabaci were recorded when adults were exposed to the dsRNA-treated plants under semi-field conditions. Foliar application of naked dsRNA reduced the ChiLCV transmission by 75% without any visible symptoms in the inoculated plants. A total of 2 consecutive sprays of dsRNA provided significant protection to B. tabaci for up to 20 days under semi-field conditions.

Transcriptomic Changes of Bemisia tabaci Asia II 1 Induced by Chilli Leaf Curl Virus Trigger Infection and Circulation in Its Vector

“…NCAM molecules also have a role in viral attachment to promote virus penetration into the host cells but inhibit the replication of rabies virus via induction of interferon β ( Hotta et al, 2007 ), which is mainly involved in innate immunity against viral infection. Silencing Fas 2 using dsRNA results in an increase of ChiLCV copies in B. tabaci Asia II 1 ( Chakraborty and Ghosh, 2022 ). This suggests that upregulation of Fas2 transcripts in B. tabaci post-ChiLCV infection is due to the innate immune response against the virus infection.…”

“…B. tabaci MEAM1 heat shock proteins (Hsp), cyclophilins, and peptidoglycan recognition protein interact with TYLCV coat protein (CP) for successful internalization ( Götz et al, 2012 ; Kanakala and Ghanim, 2016 ; Wang et al, 2016 ). Silencing of hsp70 in B. tabaci Asia II 1 inhibits transmission of ChiLCV ( Chakraborty and Ghosh, 2022 ). A GroEL homolog produced by C-type endosymbionts in B. tabaci MEAM1 is known to transport TYLCV particles through the hemolymph of B. tabaci in coated vesicles ( Bragard et al, 2013 ).…”

Effect of silencing Bemisia tabaci TLR3 and TOB1 on fitness and begomovirus transmission

“…Total RNA from the induced HT115 cells was extracted using Trizol reagent (Invitrogen, CA, USA) and resuspended in nuclease-free water. The dsRNA was purified by incubating with 1 U of RNase A, DNase and protease-free (Thermo Fisher Scientific) and 1 U of DNase I, RNase-free (Thermo Fisher Scientific) for 1 hr at 37°C in the presence of 500 mM sodium chloride as described by Chakraborty and Ghosh (2022) . The enzymes were inactivated by chloroform extraction.…”

“…However, inadequate information on the gene function of the target pest has restricted the scope of developing an RNAi-based pest management programme. Silencing of B. tabaci hsp70 and fasciclin 2 ( fas2) modulates the ChiLCV transmission ( Chakraborty and Ghosh, 2022 ). In our previous study, the differentially expressed genes (DEGs) of B. tabaci in response to ChiLCV have been reported ( Nekkanti et al., 2022 ).…”

Leaf Curl Disease a Significant Constraint in the Production of Tomato: Impact, Challenges, and Management

“…Later, Andhra Pradesh, Hyderabad [59,60], and Tamil Nadu [61] first reported the detailed characterization of ToLCV from Karnataka by Govindu and his coworkers in 1964. The prevalence of ToLCD in South India rapidly increases from 27 to 90 percent in susceptible cultivars, leading to yield losses of up to 90 percent [62]. The virus's extreme invasiveness and a dearth of efficient control methods allowed it to spread globally and cause a serious pandemic.…”