The sesquiterpene (E)-β-farnesene (EBF) is the alarm pheromone for many species of aphids 1. When released from aphids attacked by parasitoids or predators, it alerts nearby conspecifics to escape by ...walking away and dropping off the host plant 2, 3. The reception of alarm pheromone in aphids is accomplished through a highly sensitive chemosensory system. Although olfaction-related gene families including odorant receptors (ORs) and odorant-binding proteins (OBPs) have recently been identified from aphid genomes 4–6, the cellular and molecular mechanisms of EBF reception are still largely unknown. Here we demonstrate that ApisOR5, a member of the large superfamily of odorant receptors, is expressed in large placoid sensillum neurons on the sixth antennal segment and confers response to EBF when co-expressed with Orco, an obligate odorant receptor co-receptor, in parallel heterologous expression systems. In addition, the repellent behavior of Acyrthosiphon pisum to EBF disappears after knocking down ApisOR5 by RNAi as well as two A. pisum odorant-binding proteins known to bind EBF (ApisOBP3 and ApisOBP7). Furthermore, other odorants that can also activate ApisOR5, such as geranyl acetate, significantly repel A. pisum, as does EBF. Taken together, these data allow us to conclude that ApisOR5 is essential to EBF reception in A. pisum. The characterization of the EBF receptor allows high-throughput screening of aphid repellents, providing the necessary information to develop new strategies for aphid control.
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•Alarm pheromone is detected by the LP sensilla on the sixth antennal segment•ApisOR5 is essential for both electrophysiological and behavioral responses to EBF•Characterizing the EBF receptor enables high-throughput screening of aphid repellents
Zhang et al. demonstrate that the alarm pheromone (E)-β-farnesene is detected in the pea aphid by odorant receptor ApisOR5 with the cooperation of odorant-binding proteins ApisOBP3 and ApisOBP7. This study also identifies geranyl acetate as a strong repellent, paving the way for high-throughput discovery of new aphid repellents.
The freeze-thaw of early spring in China's Qinghai-Tibet Plateau is often accompanied by severe droughts. Artemisia annua, widely distributed in China, releases allelopathic substances, mainly ...artemisinin, to the environment and exerts a wide range of effects on crops. This paper studied the physiological effects of highland barley under freeze-thaw, drought, and artemisinin stress through indoor simulation experiments. The physiological response characteristics of superoxide dismutase (SOD) activity, catalase (POD) activity, net photosynthetic rate, relative water content (RWC), relative electrical conductivity, malondialdehyde (MDA) content, and soluble protein content in highland barley were analyzed. The results showed that artemisinin and drought contributed to the increase of SOD activity and the decrease of POD activity. Under the freeze-thaw stress, the SOD and POD activities both decreased firstly and then increased, but the effect of compound stress on POD was more complicated. Either artemisinin, drought, or low temperature could reduce the net photosynthetic rate of highland barley. Low temperature had more significant impacts on photosynthesis, and compound stress would show a single stress superimposed effect. Artemisinin, drought, and low temperature could reduce the RWC of highland barley, and increase the relative electrical conductivity and the concentration of soluble protein (except for low temperature stress above zero, which reduces the concentration of soluble protein). However, the effect of compound stress on soluble protein is more complex. The single stress of artemisinin and drought had no obvious effect on MDA content, while the MDA content was increased significantly under the freeze-thaw stress and the compound stress of artemisinin and drought, and the MDA content reached its peak at T1. The results are helpful to explore the effects of freeze-thaw, drought and artemisinin stress on the growth of highland barley under the background of the aridification of the Qinghai-Tibet Plateau, and provide ideas for rational agricultural management.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Uridine diphosphate (UDP)-glycosyltransferases (UGTs) are major phase II enzymes that conjugate a variety of small lipophilic molecules with UDP sugars and alter them into more water-soluble ...metabolites. Therefore, glucosidation plays a major role in the inactivation and excretion of a great variety of both endogenous and exogenous compounds. In this study, two inhibitors of UGT enzymes, sulfinpyrazone and 5-nitrouracil, significantly increased the toxicity of thiamethoxam against the resistant strain of
, which indicates that UGTs are involved in thiamethoxam resistance in the cotton aphid. Based on transcriptome data, 31
belonging to 11 families (UGT329, UGT330, UGT341, UGT342, UGT343, UGT344, UGT345, UGT348, UGT349, UGT350, and UGT351) were identified. Compared with the thiamethoxam-susceptible strain, the transcripts of 23
were elevated, and the transcripts of 13
(
, and
) were increased by approximately 2.0-fold in the resistant cotton aphid. The suppression of selected
significantly increased the insensitivity of resistant aphids to thiamethoxam, suggesting that the up-regulated
might be associated with thiamethoxam tolerance. This study provides an overall view of the possible metabolic factor
that are relevant to the development of insecticide resistance. The results might facilitate further work to validate the roles of these
in thiamethoxam resistance.
Odorant binding proteins play a crucial role in transporting semiochemicals across the sensillum lymph to olfactory receptors within the insect antennal sensilla. In this study, the general odorant ...binding protein 2 gene was cloned from the antennae of Loxostege sticticalis, using reverse transcription PCR and rapid amplification of cDNA ends. Recombinant LstiGOBP2 was expressed in Escherichia coli and purified by Ni ion affinity chromatography. Real-time PCR assays indicated that LstiGOBP2 mRNA is expressed mainly in adult antennae, with expression levels differing with developmental age. Ligand-binding experiments using N-phenyl-naphthylamine (1-NPN) as a fluorescent probe demonstrated that the LstiGOBP2 protein has binding affinity to a broad range of odorants. Most importantly, trans-11-tetradecen-1-yl acetate, the pheromone component of Loxostege sticticalis, and trans-2-hexenal and cis-3-hexen-1-ol, the most abundant plant volatiles in essential oils extracted from host plants, had high binding affinities to LstiGOBP2 and elicited strong electrophysiological responses from the antennae of adults.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Nicotine is one of the most abundant and toxic secondary plant metabolites in nature and is defined by high toxicity to plant-feeding insects. Studies suggest that increased expression of cytochrome ...P450 (CYP6CY3) and the homologous CYP6CY4 genes in Myzus persicae nicotianae is correlated with tolerance to nicotine. Indeed, through expression analyses of the CYP6CY3 and CYP6CY4 genes of different M. persicae subspecies, we determined that the mRNA levels of these two genes were much higher in M. persicae nicotianae than in M. persicae sensu stricto. We hypothesized that the expression of these two genes is subject to post-transcriptional regulation. To investigate the underlying mechanism, the miRNA profile of M. persicae nicotianae was sequenced, and twenty-two miRNAs were predicted to target CYP6CY3. Validation of these miRNAs identified two miRNAs, let-7 and miR-100, whose abundance was highly inversely correlated with the abundance of the CYP6CY3 gene. This result implies that the let-7 and miR-100 miRNAs play a major role in the post-transcriptional regulation of the CYP6CY3 gene. Modulation of the abundance of let-7 and miR-100 through the addition of inhibitors/mimics of let-7 or miR-100 to artificial diet significantly altered the tolerance of M. persicae nicotianae to nicotine, further confirming the regulatory role of these two miRNAs. Interestingly, after decreasing the transcript levels of CYP6CY3 by modulating regulatory miRNAs, the transcript levels of the homologous isozyme CYP6CY4 were significantly elevated, suggesting a compensatory mechanism between the CYP6CY3 gene and its homologous CYP6CY4 gene. Our findings provide insight into the molecular drivers of insect host shifts and reveal an important source of genetic variation for adaptive evolution in insect species.
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•Abundances of let-7 and miR-100 are less in M. persicae nicotianae compared to M. persicae s.s.•Modulation of let-7 and miR-100 impacts on CYP6CY3 expression and nicotine susceptibility.•let-7 was more effective than miR-100 to negatively regulate CYP6CY3.•let-7 and miR-100 have the opposite effect on the transcript levels of CYP6CY4 compared with CYP6CY3.
Abstract
The insecticidal crystalline proteins (Crys) are a family of insect endotoxin functioning in crop protection. As insects keep evolving into tolerance to the existing Crys, it is necessary to ...discover new Cry proteins to overcome potential threatens. Crys possess three functional domains at their N-termini, and the most active region throughout evolution was found at the domain-III. We swapped domain-IIIs from various Cry proteins and generated seven chimeric proteins. All recombinants were expressed in
Escherichia coli
and their toxicity was assessed by dietary exposure assays. Three of the seven Crys exhibited a high toxicity to Asian corn borer over the controls. One of them, Cry1Ab-Gc, a chimeric Cry1Ab being replaced with the domain-III of Cry1Gc, showed the highest toxicity to rice stem borer when it was over-expressed in
Oryza sativa
. Furthermore, it was also transformed into maize, backcrossed into commercial maize inbred lines and then produced hybrid to evaluate their commercial value. Transgenic maize performed significant resistance to the Asian corn borer without affecting the yield. We further showed that this new protein did not have adverse effects on the environment. Our results indicated that domain III swapped of Crys could be used as an efficient method for developing new engineered insecticidal protein.
As a biennial plant, Secale cereale L is usually harvested in the autumn in the northern part of China where the temperature difference between day and night is of great disparity Through the pot ...experiment, the seedlings were cut to 2, 6 and 10 cm stubble height, and the simulated freeze-thaw (FT) stress (10/- 5 degreesC) was carried out after 6 days regrowth. The physiological effects of FT with different stubble height were revealed by analyzing the relative water content (RWC), osmotic adjustment substance concentration (soluble sugar and protein), membrane peroxidation (MDA) and catalase (CAT) activity. The results demonstrated that under freeze stress (- 5 degreesC), the content of soluble protein and MDA decreased and the seedlings of 2 cm treatment kept higher level of soluble protein and MDA, while the seedlings of 6 and 10 cm treatments kept higher level of the RWC, soluble sugar content, and CAT activity. After FT stress, the content of soluble sugar and protein, RWC in the 6 cm treatment were higher than those in 2 cm and 10 cm treatments, and the CAT activity in 10 cm treatment was the highest while the MDA content is lower. These data suggest that keeping high stubble height is more adaptive for short-term FT stress.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Rapid cold hardening (RCH) is known to rapidly enhance the cold tolerance of insects. Trehalose has been demonstrated to be a cryoprotectant in
, an important invasive pest of rice in China. ...Trehalose synthesis mainly occurs through the Trehalose-6-phosphate synthase (TPS)/trehalose-6-phosphate phosphatase (TPP) pathway in insects. In this study, the
gene from
(
) was cloned and characterized for the first time. Its expression and trehalose content changes elicited by RCH were investigated. Our results revealed that RCH not only increased the survival rate of adults but also upregulated the expression level of
and increased the trehalose content under low temperature. We hypothesized that upregulated
promoted trehalose synthesis and accumulation to protect adults from low-temperature damage. To further verify the function of the
gene, we employed RNA interference (RNAi) technology. Our findings showed that RCH efficiency disappeared and the survival rate did not increase when the adults were fed dsRNA of
. Additionally, inhibiting
expression resulted in no significant difference in trehalose content between the RCH and non-RCH treatments. Furthermore, the expression patterns of trehalose transporter (
) and trehalase (
) were also affected. Collectively, these results indicate the critical role of
in
cold resistance after RCH induction.
can enhance survival ability by regulating trehalose metabolism. These findings contribute to further understanding the role of
in insect cold resistance and the invasiveness of
. Moreover, RNAi of
opens up possibilities for novel control strategies against
in the future.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The larvae of Holotrichia parallela, a destructive belowground herbivore, may cause yield losses of up to 20% in maize in a typical year. To understand the protein-level mechanisms governing the ...response of maize to this herbivore, tandem mass tag (TMT) quantitative proteomics was used for the comparative analysis of protein abundance in the maize roots after H. parallela larval attack. A total of 351 upregulated proteins and 303 downregulated proteins were identified. Pathway enrichment analysis revealed that the differentially abundant proteins (DAPs) were most strongly associated with carbohydrate and energy metabolism pathways, such as glycolysis, pentose phosphate pathway and fructose and mannose metabolism. Most glycolysis-related proteins were significantly induced. In addition, H. parallela larval attack decreased the glucose concentrations in the roots. This study demonstrates that maize can manipulate carbohydrate metabolism by modifying glycolysis and pentose phosphate pathway response to root-feeding herbivorous attackers. The results of this study may help to establish a foundation for further functional studies of key protein-mediated responses to H. parallela larvae in maize.
Trehalase is the only enzyme known for the irreversible splitting of trehalose and plays a major role in insect growth and development. In this report, we describe a basic study of the trehalase gene ...fragment encoding a soluble trehalase from Lissorhoptrus oryzophilus (LoTRE1). Sequence alignment and phylogenetic analysis suggested that LoTRE1 was similar to some known insect trehalases and belongs to the Coleoptera trehalase group. Additionally, LoTRE1 was expressed mainly in the fat body. Purified protein was obtained using heterologous expression of LoTRE1 in Escherichia coli, and the recombinant protein exhibited the ability to decompose trehalose. Enzyme–substrate docking indicated the potential involvement of other residues in the catalytic activity, in addition to Asp 333. Moreover, feeding of adults on LoTRE1 dsRNA silenced the transcription of LoTRE1 and thereby reduced the activity of trehalase and increased the trehalose content; it also led to a 12% death rate. This study reveals essential molecular features of trehalase and offers insights into the structural aspects of this enzyme, which might be related to its function. Taken together, the findings demonstrate that LoTRE1 is indispensable for adults of this pest and provide a new target for the control of L. oryzophilus.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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