Gene expression in Arabidopsis leaves after P. brassicae egg deposition, chilling, and/or herbivory by P. brassicae larvae

Plant defence against insects is well known to be affected by previous exposure to cues warning of herbivory. Using Arabidopsis thaliana and the herbivore Pieris brassicae, we addressed the question whether the maintenance of the effects of the warning cue depends on its reliability. We determined the transcriptomes of Arabidopsis leaves that were treated by P. brassicae egg deposition (i) five days after oviposition, (ii) one day after removal of the eggs following the egg treatment, (iii) three days after removal of the eggs, (iv) after two days of herbivory that started one day after removal of the eggs; or that were treated by chilling (v) five days after transfer to 4°C, (vi) one day after transfering the plants to 20°C following the chilling treatment, (vii) three days after transfering the plants to 20°C, (viii) after two days of herbivory that started one day after transfering the plants to 20°C. Arabidopsis thaliana Col-0 wild type plants were grown under short day conditions (10 h/14 h light/dark) at 20°C for 7 weeks. Subsequently (i) the plants were transferred to 4°C for 5 days, or (ii) Pieris brassicae deposited ca. 40 eggs on leaf 17 where they remained for five days, or (iii) as controls plants grew untreated for five days. Next, the plants were transferred back to 20°C and the eggs were removed, respectively. Next, all plants rested for 1 day at 20°C. Next, P. brassicae larvae were allowed to feed for 2 days on leaf 17 adjacent to the former egg deposit site or at a respective leaf region of chilling-treated or untreated plants. Control plants were not exposed to larvae. From all treated and untreated plants material from a leaf region proximal to the egg deposition and/or feeding site was harvested for transcriptome analysis.