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

Plants can prepare their defense of impending herbivory, when they previously perceived eggs deposited by herbivores insect which reliably indicates that larvae will soon hatch and feed on the plants. Using Arabidopsis thaliana and Pieris brassicae we addressed the question whether prior egg deposition affects transcriptional changes in feeding-damaged plants. We determined the transcriptomes of Arabidopsis leaves that (i) were for six days deposited with eggs and suffered larval feeding for two days, (ii) suffered larval feeding for two days without prior egg deposition or (iii) were left untreated. Arabidopsis thaliana Col-0 wild type plants were grown under short day conditions at 20°C for seven weeks (6 weeks: 10 h/14 h light/dark + 1 week: 8 h/ 16 h light/dark). Seven week old plants were (i) deposited with eggs (one egg cluster with about 40 eggs was deposited onto the lower surface of a rosette leaf within position 14-17) or were (ii) left untreated. Six days after egg deposition a defined number of larvae was allowed to feed for two days on the leaf which carried the former egg cluster or on leaf with corresponding position of the untreated plants. Control plants were left untreated. From treated and untreated plants, tissue from a leaf region proximal to the egg deposition and/or feeding site was harvested for transcriptome analysis