Effects of two folivorous insect species on the aliphatic glucosinolate profile in Arabidopsis thaliana ecotype crosses

Effects of two folivorous insect species on the aliphatic glucosinolate profile in Arabidopsis thaliana ecotype crosses Glucosinolates (GSs) are part of a two-component defence system, characteristic for the Brassicales, including the model species Arabidopsis thaliana (L.) HEYNH. Plants alter their GS levels dynamically in response to insect feeding by generalist and specialist insects. Therefore, we have investigated the specific biochemical and molecular plant responses of A. thaliana crosses possessing a different aliphatic GS profile. Lines were differently responsive to herbivory of the generalist Spodoptera exigua (HUBNER) and specialist Pieris brassicae L. In some but not in all lines aliphatic GS increased significantly after feeding by the caterpillars. Differently, pronounced increases within indolyl GS levels were induced in many lines after feeding of the crucifer specialist P brassicae. Especially 1-methoxy-3-indolylmethyl GS was induced by this insect. Transcript levels of genes associated with aliphatic and indolyl GS biosynthesis as well as other genes induced by insect feeding (PR4) and defence signalling (CaEF and BGL) were measured for selected lines. Alterations in GS content were often related with changes in transcript levels of GS biosynthesis genes. Herbivory of S. exigua and P brassicae leads to similar changes in transcript levels of observed genes.