Differential Expression of Candidate Defense Genes of Poplars in Response to Aphid Feeding

Abstract

Species belonging to the genus Populus (poplars) produce a series of defensive proteins in response to insect damage. Proteinase inhibitors, polyphenol oxidases, and chitinases are the most relevant and intensively studied proteins. Most of the knowledge about the relation between these proteins and herbivores has been obtained from studies with chewing insects. Nothing is known about whether phloem-feeder insects such as aphids are able to trigger a comparable response. In the current study, the expression of genes encoding a Kunitz trypsin inhibitor 3 (KTI3), a polyphenol oxidase 1 (PPO1), and a class I chitinase (CHI) was characterized in two poplar hybrids (one resistant hybrid and one susceptible hybrid, to aphids) attacked by the aphid Chaitophorus leucomelas Koch. The expression pattern was analyzed using a semiquantitative reverse transcription-polymerase chain reaction approach. The expression of KTI3 was increased by aphids only in the aphid-susceptible hybrid. Differently, PPO1 expression was increased by aphids in the aphid-resistant hybrid. The expression of CHI was down-regulated by aphids in the susceptible hybrid. This is the first study to report the differential expression of poplar defense genes in response to phloem-feeder insects such as aphids. The findings from the current study suggest that the expression levels of defensive proteins are affected by poplar genotype and by aphid infestation.

Comparative transcriptome analysis of Gossypium hirsutumL. in response to sap sucking insects: aphid and whitefly

“…The mechanisms are either inherent constitutive defenses, which include physical barriers such as cell wall and cuticle, or induced defense mechanisms in response to insect attacks [3]. The induced defense mechanisms also include the activation of proteinase inhibitor [4], polyphenol oxidase, chitinases, and so on [5] and the release of secondary metabolites, which attract the parasitoid of attacked insects [3]. The induced defense mechanism has recently been demonstrated to be mediated through SA (Salicylic acid) [6], JA (Jasmonic acid) [7], or ET (Ethylene) pathway [8].…”

Peroxidase and Polyphenol Oxidase Activity in Moderate Resistant and Susceptible Vicia faba Induced by Aphis craccivora (Hemiptera: Aphididae) Infestation

“…The increased activities of these enzymes in a plant are considered as a resistant state of the plant to the insect pest ( Wei et al. 2007 , Ramírez et al. 2009 , Gulsen et al.…”

Influence of Genotype, Environment, and Gypsy Moth Herbivory on Local and Systemic Chemical Defenses in Trembling Aspen (Populus tremuloides)

“…A number of studies (e.g., Glynn et al 2003;Haruta et al 2001;Osier and Lindroth 2004;Ramirez et al 2009;Stevens and Lindroth 2005) have considered either local or systemic induction of carbon-or protein-based defenses in Populus, and a few (Boeckler et al 2013;Haruta et al 2001;Philippe et al 2010) have differentiated between concurrent induction of local and systemic defenses. Finally, one study measured transcription of genes associated with a variety of chemical defenses in P. nigra (Babst et al 2009), but did not measure the actual defense chemicals.…”