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A protein from the salivary glands of the pea aphid, Acyrthosiphon pisum, is essential in feeding on a host plant. Proc Natl Acad Sci U S A

Department of Entomology, Kansas State University, Manhattan, KS 66506, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 08/2008; 105(29):9965-9. DOI: 10.1073/pnas.0708958105
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ABSTRACT In feeding, aphids inject saliva into plant tissues, gaining access to phloem sap and eliciting (and sometimes overcoming) plant responses. We are examining the involvement, in this aphid-plant interaction, of individual aphid proteins and enzymes, as identified in a salivary gland cDNA library. Here, we focus on a salivary protein we have arbitrarily designated Protein C002. We have shown, by using RNAi-based transcript knockdown, that this protein is important in the survival of the pea aphid (Acyrthosiphon pisum) on fava bean, a host plant. Here, we further characterize the protein, its transcript, and its gene, and we study the feeding process of knockdown aphids. The encoded protein fails to match any protein outside of the family Aphididae. By using in situ hybridization and immunohistochemistry, the transcript and the protein were localized to a subset of secretory cells in principal salivary glands. Protein C002, whose sequence contains an N-terminal secretion signal, is injected into the host plant during aphid feeding. By using the electrical penetration graph method on c002-knockdown aphids, we find that the knockdown affects several aspects of foraging and feeding, with the result that the c002-knockdown aphids spend very little time in contact with phloem sap in sieve elements. Thus, we infer that Protein C002 is crucial in the feeding of the pea aphid on fava bean.

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Available from: Ming-Shun Chen, Aug 20, 2015
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    • "Aphid effectors are able to promote aphid virulence upon transient and/or transgenic over expression. For example, the effector C002, which was first identified in A. pisum, is an abundant salivary protein that is essential for aphid feeding (Mutti et al. 2008). "
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    ABSTRACT: The perception of aphid infestation induces highly coordinated and sequential defensive reactions in plants at the cellular and molecular levels. The aim of the study was to explore kinetics of induced antioxidative defence responses in leaf cells of Pisum sativum L.cv. Cysterski upon infestation of the pea aphid Acyrthosiphon pisum at varying population sizes, including accumulation of flavonoids, changes of carbon metabolism, and expression of nuclear genes involved in sugar transport. Within the first 96 h, after A. pisum infestation, flavonoid accumulation and increased peroxidase activity were observed in leaves. The level of pisatin increased after 48 h of infestation and reached a maximum at 96 h. At this time point, a higher concentration of flavonols was observed in the infested tissue than in the control. Additionally, strong post-infestation accumulation of chalcone synthase (CHS) and isoflavone synthase (IFS) transcription products was also found. The levels of sucrose and fructose in 24-h leaves infested by 10, 20, and 30 aphids were significantly lower than in the control. Moreover, in leaves infested by 30 aphids, the reduced sucrose level observed up to 48 h was accompanied by a considerable increase in the expression level of the PsSUT1 gene encoding the sucrose transporter. In conclusion, A. pisum infestation on pea leads to stimulation of metabolic pathways associated with defence.
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    • " - down in various insects have been previously documented . Injection of dsRNA directly into the insect hemocoel is the most common method of delivery . For example , injection of C002 dsRNA into the pea aphid , Acyrthosiphon pisum , resulted in down - regulation of the endogenous transcript and in reduced survival of aphids on fava bean plants ( Mutti et al . , 2006 , 2008 ) . Beet armyworm , Spodoptera exigua , injected with chitin synthase dsRNA displayed larval abnormalities such as disorder in the insect cuticle and no expansion of the trachea epithelial wall ( Chen et al . , 2008 ) . Likewise , injection of the red flour beetle , Tribolium casta - neum , with chitin synthase dsRNA resulted in disrupt"
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    • "The effector C002, which was first identified in A. pisum, is an abundant salivary protein that is essential for aphid feeding (Mutti et al., 2008). When C002 transcription is reduced by RNA interference (RNAi) in the pea aphid, aphid lethality increases as aphids have difficulties reaching the sieve tube elements (Mutti et al., 2006, 2008). Further characterization of the C002 ortholog from M. persicae (MpC002) showed this protein promotes aphid virulence upon overexpression in N. benthamiana leaf discs (Bos et al., 2010b). "
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