Effect of Serendipita indica-infection on the gene expression in wild-type and YUC9 overexpressing Arabidopsis thaliana plants

The root-colonizing fungal endophyte Serendipita indica, formerly known as Piriformospora indica, is well known to promote plant biomass production and stress tolerance of its host plants. Moreover, previous studies highlighted an important impact of the fungus on auxin homeostasis during the infection of Arabidopsis thaliana plants. Auxin is a key determinant of plant growth, including the growth of the root system. Auxin overproducing mutants, like for instance YUC9oe (Hentrich et al., 2013 Plant J.), show a pronounced root phenotype that can be restored by the co-cultivation with S. indica. We here report the comparative analysis of the effect of a mock- and S. indica-infection on both wild-type Arabidopsis plants (Col-0) and YUC9 overexpressing mutants. Our data provide evidence for the induction of GRETCHEN HAGEN 3 (GH3) genes that are involved in conjugating active free indole-3-acetic acid with amino acids. The fungus triggered induction GH3s is suggested to be involved in affecting the cellular auxin homeostasis. To investigate differential gene expression in mock- (WOP) and S. indica-infected (WP) Arabidopsis wild-type plants (Col-0) and YUC9 overexpression mutants