Towards global understanding of plant defence against aphids – timing and dynamics of early Arabidopsis defence responses to cabbage aphid (Brevicoryne brassicae) attack

Abstract

Insect feeding on plants causes a complex series of coordinated defence responses. Little is known, however, about the time-dependent aspect of induced changes. Here we present a time series-based investigation of Arabidopsis thaliana Ler subjected to attack by a specialist pest of Brassicaceae species, Brevicoryne brassicae. Transcriptome and metabolome changes were studied at 6, 12, 24 and 48 h after infestation to monitor the progress of early induced responses. The use of full-genome oligonucleotide microarrays revealed the initiation of extensive gene expression changes already during the first 6 h of infestation. Data indicated the involvement of reactive oxygen species (ROS) and calcium in early signalling, and salicylic acid (SA) and jasmonic acid (JA) in the regulation of defence responses. Transcripts related to senescence, biosynthesis of antiinsect proteins, indolyl glucosinolates (GS) and camalexin, as well as several uncharacterized to date WRKY transcription factors, were induced. Follow-up studies of defenceinvolved secondary metabolites revealed depositions of callose at the insects' feeding sites, a decrease in the total level of aliphatic GS, particularly 3-hydroxypropyl glucosinolate, and accumulation of 4-methoxyindol-3-ylmethyl glucosinolate 48 h after the attack. The novel role of camalexin, induced as a part of defence against aphids, was verified in fitness experiments. Fecundity of B. brassicae was reduced on camalexin-accumulating wild-type (WT) plants as compared with camalexin-deficient pad3-1 mutants. Based on experimental data, a model of plant-aphid interactions at the early phase of infestation was proposed.

Transcriptomics of induced defense responses to greenbug aphid feeding in near isogenic wheat lines

“…After sensing aphid feeding, Ca 2+ sensors activate downstream defense signaling cascades by increasing expression of calmodulin, calmodulin binding proteins, and calcium-dependent protein kinases (CDPKs) [21]. The role of ROS in mediating herbivore attack by either chewing or piercing/sucking insects is unquestionable; however, the nature of response depends on type of herbivory and duration and intensity of feeding [4,[22][23][24].…”

Defence mechanisms of Brassicaceae: implications for plant-insect interactions and potential for integrated pest management. A review

“…Glucosinolate levels and proportions of individual glucosinolate compounds have been demonstrated to be altered due to the damage caused by several insect pests (Koritsas et al, 1991;Bodnaryk, 1992;Hopkins et al, 1998). The glucosinolate concentration can increase in response to herbivore feeding, and this high level of glucosinolates can affect both generalist and specialist herbivores, and glucosinolates can be equally effective as stimulants as well as deterrents (Bodnaryk, 1992;Bartlet et al, 1999;Li et al, 2000;Rask et al, 2000;Agrawal and Kurashige, 2003;Kuśnierczyk et al, 2007Kuśnierczyk et al, , 2008Gols et al, 2008a).…”

Callose Synthase GSL7 Is Necessary for Normal Phloem Transport and Inflorescence Growth in Arabidopsis

“…Expression of the GSL6 gene is elevated and callose is deposited locally in response to phloem feeding by silverleaf whitefly nymphs (Bemisia sp. ; Kempema et al, 2007) and the aphid Brevicoryne brassicae (Kuśnierczyk et al, 2008). The isoform(s) responsible for the synthesis of callose in sieve plate pores has yet to be identified.…”