Amino acid composition of phloem sap and the relation to intraspecific variation in pea aphid (Acyrthosiphon pisum) performance

Sandström, Jonas; Pettersson, Jan

doi:10.1016/0022-1910(94)90133-3

Cited by 203 publications

(204 citation statements)

References 24 publications

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“…Since aphids feed from the phloem sap and seem highly dependent on amino acid composition (Sandström & Pettersson, 1994), the effects on aphid performance that we have seen in our experiments might also be related to variation in the phloem sap. However we have not been able to analyse the phloem in our experiments.…”

Section: Discussionmentioning

confidence: 73%

The effect of different plant nutrient regimes on the aphid Macrosiphum euphorbiae growing on petunia

Jansson

Ekbom

2002

Entomologia Exp Applicata

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Three experiments were conducted to study how nutrient content of the host plant, Petunia axillaris hybrida Villm. Grandiflora Group, affects the performance of Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae). Aphid performance was analysed in relation to plant nutrient levels and the ratio of nitrogen to potassium (N/K). Phosphorus (P) had a positive effect on several parameters of aphid performance. Both P and K were associated with a short development time but a strong correlation between P and K content made it impossible to detect their relative importance. In one experiment aphid performance was significantly lower on unfertilised plants with low N content, suggesting a positive effect of N. A high N/K ratio did not, in general, increase aphid performance. The complexity of plant nutrient content on aphid performance suggests that not only nutrient levels but also ratios of nutrients must be considered.

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Section: Discussionmentioning

confidence: 73%

The effect of different plant nutrient regimes on the aphid Macrosiphum euphorbiae growing on petunia

Jansson

Ekbom

2002

Entomologia Exp Applicata

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“…Of the two copies of the gene corresponding to the single step in the asparagine pathway (6.3.5.4), both copies are weakly expressed (Table 1). Because asparagine is the dominant amino acid found in phloem of A. pisum host plants (2,19,20), it is expected to be present in excess, making its biosynthesis unimportant. All four nonessential amino acid pathways (glutamate, glutamine, aspartate, and serine) that generate required amino group donors for Buchnera's essential amino acid pathways are significantly up-regulated in the bacteriocyte relative to the body ( Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies (21,22) showed that glutamine and asparagine are the most abundant amino acids in pea aphid hemolymph. Because phloem concentrations of amino acids do impact hemolymph amino acid levels (23), this potentially results from the high concentrations of these two amino acids in ingested phloem (2,19,20) but may also reflect their generation within aphid tissues. Ammonia waste from aphid tissues may be used for glutamine production via GS, with the resulting glutamine imported into bacteriocytes, where it can contribute to glutamate production.…”

Section: And Table 1)mentioning

confidence: 99%

“…As a diet, phloem sap is low in nitrogen and especially low in essential amino acids (1)(2)(3). Phloem-feeding insects require microbial symbionts to synthesize essential amino acids (4,5).…”

mentioning

confidence: 99%

“…Most nitrogen available in phloem sap is in the form of free amino acids, predominantly a small subset of nonessential amino acids (15). In phloem sap directly obtained from pea aphid stylets, a few nonessential amino acids, including asparagine, glutamine, and glutamate, dominate in several host plant species used by this aphid (2). Seven nonessential amino acids (glutamate, aspartate, serine, glutamine, alanine, proline, and asparagine) are not synthesized by Buchnera; therefore, the host aphid must synthesize these amino acids and/or obtain them from the diet.…”

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confidence: 99%

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Aphid genome expression reveals host–symbiont cooperation in the production of amino acids

Hansen

Moran

2011

Proc. Natl. Acad. Sci. U.S.A.

365

478

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The evolution of intimate symbiosis requires the coordination of gene expression and content between the distinct partner genomes; this coordination allows the fusion of capabilities of each organism into a single integrated metabolism. In aphids, the 10 essential amino acids are scarce in the phloem sap diet and are supplied by the obligate bacterial endosymbiont ( Buchnera ), which lives inside specialized cells called bacteriocytes. Although Buchnera ’s genome encodes most genes for essential amino acid biosynthesis, several genes in essential amino acid pathways are missing, as are most genes for production of nonessential amino acids. Additionally, it is unresolved whether the supply of nitrogen for amino acid biosynthesis is supplemented by recycling of waste ammonia. We compared pea aphid gene expression between bacteriocytes and other body tissues using RNA sequencing and pathway analysis and exploiting the genome sequences available for both partners. We found that 26 genes underlying amino acid biosynthesis were up-regulated in bacteriocytes. Seven of these up-regulated genes fill the gaps of Buchnera ’s essential amino acid pathways. In addition, genes underlying five nonessential amino acid pathways lost from Buchnera are up-regulated in bacteriocytes. Finally, our results reveal that two genes, glutamine synthetase and glutamate synthase, which potentially work together in the incorporation of ammonium nitrogen into glutamate (GOGAT) cycle to assimilate ammonia into glutamate, are up-regulated in bacteriocytes. Thus, host gene expression and symbiont capabilities are closely integrated within bacteriocytes, which function as specialized organs of amino acid production. Furthermore, the GOGAT cycle may be a key source of nitrogen fueling the integrated amino acid metabolism of the aphid– Buchnera partnership.

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Solute Transport in the Phloem

Pritchard¹

2007

Plant Solute Transport

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Amino acid composition of phloem sap and the relation to intraspecific variation in pea aphid (Acyrthosiphon pisum) performance

Cited by 203 publications

References 24 publications

The effect of different plant nutrient regimes on the aphid Macrosiphum euphorbiae growing on petunia

The effect of different plant nutrient regimes on the aphid Macrosiphum euphorbiae growing on petunia

Aphid genome expression reveals host–symbiont cooperation in the production of amino acids

Solute Transport in the Phloem

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