Barley transcriptome analyses upon interaction with different aphid species identify thionins contributing to resistance

Abstract

Aphids are phloem‐feeding insects that cause yield loss on a wide range of crops, including cereals such as barley. Whilst most aphid species are limited to one or few host species, some are able to reproduce on many plants belonging to different families. Interestingly, aphid probing behaviour can be observed on both host and non‐host species, indicating that interactions take place at the molecular level that may impact host range. Here, we aimed to gain insight into the interaction of barley with aphid species differing in their ability to infest this crop by analysing transcriptional responses. Firstly, we determined colonization efficiency, settlement and probing behaviour for the aphid species Rhopalosiphum padi , Myzus persicae and Myzus cerasi, which defined host, poor‐host and non‐host interactions, respectively. Analyses of barley transcriptional responses revealed gene sets differentially regulated upon the different barley–aphid interactions and showed that the poor‐host interaction with M. persicae resulted in the strongest regulation of genes. Interestingly, we identified several thionin genes strongly up‐regulated upon interaction with M. persicae , and to a lesser extent upon R. padi interaction. Ectopic expression of two of these genes in Nicotiana benthamiana reduced host susceptibility to M. persicae , indicating that thionins contribute to defences against aphids.

Abstract

Non‐host and poor‐host resistance to aphids is poorly understood and is key for development of novel crop resistances to insect pests. Here, we used barley as a monocot model crop plant to study the interaction with aphid species that differ in their ability to infest and analysed barley transcriptional responses during interactions. Our work provides insights into how barley responds to different types of aphid interactions. Importantly, we identified barley genes contributing to plant defences against aphids.