Plant immunity in plant–aphid interactions

Abstract

Aphids are economically important pests that cause extensive feeding damage and transmit viruses. While some species have a broad host range and cause damage to a variety of crops, others are restricted to only closely related plant species. While probing and feeding aphids secrete saliva, containing effectors, into their hosts to manipulate host cell processes and promote infestation. Aphid effector discovery studies pointed out parallels between infection and infestation strategies of plant pathogens and aphids. Interestingly, resistance to some aphid species is known to involve plant resistance proteins with a typical NB-LRR domain structure. Whether these resistance proteins indeed recognize aphid effectors to trigger ETI remains to be elucidated. In addition, it was recently shown that unknown aphid derived elicitors can initiate reactive oxygen species (ROS) production and callose deposition and that these responses were dependent on BAK1 (BRASSINOSTERIOD INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1) which is a key component of the plant immune system. In addition, BAK-1 contributes to non-host resistance to aphids pointing to another parallel between plant-pathogen and – aphid interactions. Understanding the role of plant immunity and non-host resistance to aphids is essential to generate durable and sustainable aphid control strategies. Although insect behavior plays a role in host selection and non-host resistance, an important observation is that aphids interact with non-host plants by probing the leaf surface, but are unable to feed or establish colonization. Therefore, we hypothesize that aphids interact with non-host plants at the molecular level, but are potentially not successful in suppressing plant defenses and/or releasing nutrients.

Understanding Plant Immunity as a Surveillance System to Detect Invasion

“…Yet, it is clear that they both have the capacity to activate and suppress plant immune responses (55,66). Nematodes secrete effectors to suppress immune responses and increase virulence, and likely produce DAMPs.…”

Redox Control of Aphid Resistance through Altered Cell Wall Composition and Nutritional Quality

“…In particular, this analysis highlighted the importance of wall-associated kinases and receptor-like kinases, particularly those containing the Domain of Unknown Function26 (Foyer et al, 2015). Similarities between plant-aphid and plant-pathogen interactions have been suggested by demonstration of the involvement of plant resistance factors such as the NB-LRR domain finality proteins and the BRASSINOSTERIOD INSENSITIVE1-ASSOCIATED RECEPTOR KINASE1 in plant responses to aphids (Bos et al, 2010b;Jaouannet et al, 2014;Prince et al, 2014). The perception of environmental threats results in the production of an oxidative burst that involves the generation of reactive oxygen species (ROS) in the apoplast (Bos et al, 2010a(Bos et al, , 2010bJaouannet et al, 2014).…”

“…Similarities between plant-aphid and plant-pathogen interactions have been suggested by demonstration of the involvement of plant resistance factors such as the NB-LRR domain finality proteins and the BRASSINOSTERIOD INSENSITIVE1-ASSOCIATED RECEPTOR KINASE1 in plant responses to aphids (Bos et al, 2010b;Jaouannet et al, 2014;Prince et al, 2014). The perception of environmental threats results in the production of an oxidative burst that involves the generation of reactive oxygen species (ROS) in the apoplast (Bos et al, 2010a(Bos et al, , 2010bJaouannet et al, 2014). Increasing literature evidence suggests that aphid-induced increases in ROS levels, together with the differential expression of genes involved in ROS generation and responses to oxidative stress, are important in the plant response to aphids and to other phloem-feeding insects (Moloi and van der Westhuizen, 2006;Kerchev et al, 2012aKerchev et al, , 2012bMai et al, 2013Liang et al, 2015Borowiak-Sobkowiak et al, 2016).…”

“…While the progress of the stylets through the host cell walls is considered to be too fast to allow significant metabolism by these the enzymes, the presence of these activities will undoubtedly contribute to the generation of signals that alert the host cells to the presence of the herbivore. Moreover, these and other proteins in saliva are considered to function as effectors that manipulate host cell processes and promote infestation (Jaouannet et al, 2014).…”

OXI1 kinase plays a key role in resistance of Arabidopsis towards aphids (Myzus persicae)

“…The plant-aphid interaction is complex and highly dynamic, subject to continual change (Mello and Silva-Filho 2002). Recently, studies have shown that aphids secrete effectors that modulate plant defence responses (Bos et al 2010;Atamian et al 2013;Pitino and Hogenhout 2013) pointing to parallels between plant-pathogen and plant-insect interactions (Jaouannet et al 2014). It has been suggested that two different processes are involved in the elicitation of plant defence.…”