Induced expression of defence-related genes in barley is specific to aphid genotype

Abstract

Understanding the mechanisms by which plants respond to attack is of great ecological and economic importance. When phloem‐feeding insects feed they can influence the expression of defence‐related genes in the plant. While it is well‐documented that the genotype of the feeding insect can influence plant fitness traits, thus far the effect of insect genotype on the induction of defence‐related genes in the plant has had relatively little attention. To investigate the molecular specificity of plant–insect interactions, the model plant Hordeum vulgare was exposed to four different genotypes of the aphid Sitobion avenae. When the plants were previously exposed to a specific aphid genotype, the population growth of other aphid genotypes was reduced. A global gene expression study of the barley genome showed that these effects can occur indirectly through physiological changes in the plant. We found 1018 transcripts to be differentially induced by different aphid genotypes, with some specific to one aphid genotype. This work identifies core and genotype‐specific plant response genes to aphids and supports the notion that the genotypic composition of the herbivore population can trigger the transcription of different defence‐related genes in the host plant, thus affecting the population structure of these herbivores and potentially the wider ecological community.

Plant Genes Benefitting Aphids—Potential for Exploitation in Resistance Breeding

“…in barley with monogenic resistance to S. graminum , pre-infestation with a non-compatible aphid biotype led to reduced feeding by a compatible biotype, indicating defense induction by the former (Hays et al, 1999). Similarly, Zytynska et al (2016) found biotype-dependant induction of numerous transcripts and reduction of aphid population growth of S. avenae in barley. In neither of these two barley studies were there aphid biotypes that induced susceptibility to another biotype though.…”

Soil microbe-induced plant resistance alters aphid inter-genotypic competition leading to rapid evolution with consequences for plant growth and aphid abundance

“…Since the temperature in the experiment was above the threshold temperature that male aphids are produced, the changes in the relative genotype frequency in aphid population are due to the differentially growth rate of the two clonally reproducing genotypes. Different aphid genotypes induce variable plant defences when feeding, with fitness consequences for other aphid genotypes (Zytynska et al 2016), and these will also vary among plant varieties (Delp et al 2009). Aphids also release salivary proteins into the plant to facilitate feeding and suppress plant defences (Yates & Michel 2018) and it is likely that genetic variation in both the aphid and plant influence the outcome of these interactions.…”

“…As aphids feed they induce plant defences, which also vary dependent on the plant (Delp et al . 2009) and aphid genotype (Zytynska et al . 2016).…”

“…Aphids are sap-sucking insects that exhibit substantial variation in acceptance and subsequent growth rates across different plant genotypes (Ninkovic & Åhman 2009). As aphids feed they induce plant defences, which also vary dependent on the plant (Delp et al 2009) and aphid genotype (Zytynska et al 2016). In response, aphids can deliver effector proteins to the plant via their saliva that suppress plant defences, enabling higher reproductive output for the feeding aphids particularly in the local area (Escudero-Martinez et al 2020).…”

Metabotype variation in a field population of tansy plants influences aphid host selection

“…Aphids are sucking insects and feed from the phloem of plants (Harrewijn, Minks, & Mollema, ; Kehr, ). Even though they do not cause as much physical damage as chewing herbivores do, they can have large effects on plants by extracting nutrients and are known to induce defence responses within the plant (Fidantsef, Stout, Thaler, Duffey, & Bostock, ; Voelckel, Weisser, & Baldwin, ; Zytynska, Jourdie, Naseeb, Delneri, & Preziosi, ), including triggering the emission of sesquiterpenes (Bernasconi, Turlings, Ambrosetti, Bassetti, & Dorn, ). Differences between plant genotypes, or between plants of different nutrient status, strongly affect aphid growth (Zytynska & Weisser, ).…”