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Testing insecticidal activity of novel chemically synthesized siRNA against Plutella xylostella under laboratory and field conditions.

Gong L, Chen Y, Hu Z, Hu M - PLoS ONE (2013)

Bottom Line: Quantitative Real-time PCR was used to confirm silencing and detected that the transcript levels of P. xylostella AChE2 (PxAChE2) were reduced by 5.7-fold compared to the control group.Finally, effects of the siRNAs on treated plants of Brassica oleracea and Brassica alboglabra were investigated with different siRNA doses.Our results showed that Si-ace2_001 had no negative effects on plant morphology, color and growth of vein under our experimental conditions.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Pesticide and Chemical Biology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, China.

ABSTRACT

Background: Over the last 60 years, synthetic chemical pesticides have served as a main tactic in the field of crop protection, but their availability is now declining as a result of the development of insect resistance. Therefore, alternative pest management agents are needed. However, the demonstration of RNAi gene silencing in insects and its successful usage in disrupting the expression of vital genes opened a door to the development of a variety of novel, environmentally sound approaches for insect pest management.

Methodology/principal findings: Six small interfering RNAs (siRNAs) were chemically synthesized and modified according to the cDNA sequence of P. xylostella acetylcholine esterase genes AChE1 and AChE2. All of them were formulated and used in insecticide activity screening against P. xylostella. Bioassay data suggested that Si-ace1_003 and Si-ace2_001 at a concentration of 3 µg cm(-2) displayed the best insecticidal activity with 73.7% and 89.0%, mortality, respectively. Additional bioassays were used to obtain the acute lethal concentrations of LC50 and LC90 for Si-ace2_001, which were 53.66 µg/ml and 759.71 µg/ml, respectively. Quantitative Real-time PCR was used to confirm silencing and detected that the transcript levels of P. xylostella AChE2 (PxAChE2) were reduced by 5.7-fold compared to the control group. Consequently, AChE activity was also reduced by 1.7-fold. Finally, effects of the siRNAs on treated plants of Brassica oleracea and Brassica alboglabra were investigated with different siRNA doses. Our results showed that Si-ace2_001 had no negative effects on plant morphology, color and growth of vein under our experimental conditions.

Conclusions: The most important finding of this study is the discovery that chemically synthesized and modified siRNA corresponding to P. xylostella AChE genes cause significant mortality of the insect both under laboratory and field conditions, which provides a novel strategy to control P. xylostella and to develop bio-pesticides based on the RNA interference technology.

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Corrected mortality of Si-ace2_001 against the larvae of Plutella xylostella in the field trial.Decamethrin (2.5% EC) was used as a positive control.
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pone-0062990-g003: Corrected mortality of Si-ace2_001 against the larvae of Plutella xylostella in the field trial.Decamethrin (2.5% EC) was used as a positive control.

Mentions: Two P. xylostella AChE genes were targeted by chemically synthesized siRNAs. We detected that Si-ace2_001which had the highest insecticidal effectiveness, causing 89% mortality at 72 h after exposure (Figure 1). In the case of P. xylostella AChE1, Si-ace1_003 was shown the most insecticidal against P. xylostella, inducing 73.7% mortality (Figure 1). The acute lethal concentrations of LC50 and LC90 for Si-ace2_001 were 53.66 µg/ml and 759.71 µg/ml, respectively (Table 2, Figure 2). Lethal concentration LC50 of Si-ace2_001 with corresponding 95% fiducial limits of the upper confidence limit and the lower confidence limit were 72.44 µg/ml and 39.76 µg/ml, respectively (Table 2). Treatment with the Si-ace2_001 in field bioassays for 5 days at concentrations of 200 µg/ml, 100 µg/ml and 50 µg/ml resulted in 58.8%, 48.4% and 42.4% mortality, respectively. This mortality was even higher than the 7 days after treatment (Figure 3, Table 3). The positive control of Decamethrin (2.5% EC) showed a strong toxicity towards P. xylostella with 89.8% at 5 days and 79.0% at 7 days (Figure 3, Table3).


Testing insecticidal activity of novel chemically synthesized siRNA against Plutella xylostella under laboratory and field conditions.

Gong L, Chen Y, Hu Z, Hu M - PLoS ONE (2013)

Corrected mortality of Si-ace2_001 against the larvae of Plutella xylostella in the field trial.Decamethrin (2.5% EC) was used as a positive control.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646892&req=5

pone-0062990-g003: Corrected mortality of Si-ace2_001 against the larvae of Plutella xylostella in the field trial.Decamethrin (2.5% EC) was used as a positive control.
Mentions: Two P. xylostella AChE genes were targeted by chemically synthesized siRNAs. We detected that Si-ace2_001which had the highest insecticidal effectiveness, causing 89% mortality at 72 h after exposure (Figure 1). In the case of P. xylostella AChE1, Si-ace1_003 was shown the most insecticidal against P. xylostella, inducing 73.7% mortality (Figure 1). The acute lethal concentrations of LC50 and LC90 for Si-ace2_001 were 53.66 µg/ml and 759.71 µg/ml, respectively (Table 2, Figure 2). Lethal concentration LC50 of Si-ace2_001 with corresponding 95% fiducial limits of the upper confidence limit and the lower confidence limit were 72.44 µg/ml and 39.76 µg/ml, respectively (Table 2). Treatment with the Si-ace2_001 in field bioassays for 5 days at concentrations of 200 µg/ml, 100 µg/ml and 50 µg/ml resulted in 58.8%, 48.4% and 42.4% mortality, respectively. This mortality was even higher than the 7 days after treatment (Figure 3, Table 3). The positive control of Decamethrin (2.5% EC) showed a strong toxicity towards P. xylostella with 89.8% at 5 days and 79.0% at 7 days (Figure 3, Table3).

Bottom Line: Quantitative Real-time PCR was used to confirm silencing and detected that the transcript levels of P. xylostella AChE2 (PxAChE2) were reduced by 5.7-fold compared to the control group.Finally, effects of the siRNAs on treated plants of Brassica oleracea and Brassica alboglabra were investigated with different siRNA doses.Our results showed that Si-ace2_001 had no negative effects on plant morphology, color and growth of vein under our experimental conditions.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Pesticide and Chemical Biology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou, China.

ABSTRACT

Background: Over the last 60 years, synthetic chemical pesticides have served as a main tactic in the field of crop protection, but their availability is now declining as a result of the development of insect resistance. Therefore, alternative pest management agents are needed. However, the demonstration of RNAi gene silencing in insects and its successful usage in disrupting the expression of vital genes opened a door to the development of a variety of novel, environmentally sound approaches for insect pest management.

Methodology/principal findings: Six small interfering RNAs (siRNAs) were chemically synthesized and modified according to the cDNA sequence of P. xylostella acetylcholine esterase genes AChE1 and AChE2. All of them were formulated and used in insecticide activity screening against P. xylostella. Bioassay data suggested that Si-ace1_003 and Si-ace2_001 at a concentration of 3 µg cm(-2) displayed the best insecticidal activity with 73.7% and 89.0%, mortality, respectively. Additional bioassays were used to obtain the acute lethal concentrations of LC50 and LC90 for Si-ace2_001, which were 53.66 µg/ml and 759.71 µg/ml, respectively. Quantitative Real-time PCR was used to confirm silencing and detected that the transcript levels of P. xylostella AChE2 (PxAChE2) were reduced by 5.7-fold compared to the control group. Consequently, AChE activity was also reduced by 1.7-fold. Finally, effects of the siRNAs on treated plants of Brassica oleracea and Brassica alboglabra were investigated with different siRNA doses. Our results showed that Si-ace2_001 had no negative effects on plant morphology, color and growth of vein under our experimental conditions.

Conclusions: The most important finding of this study is the discovery that chemically synthesized and modified siRNA corresponding to P. xylostella AChE genes cause significant mortality of the insect both under laboratory and field conditions, which provides a novel strategy to control P. xylostella and to develop bio-pesticides based on the RNA interference technology.

Show MeSH
Related in: MedlinePlus