The transcriptome of StRIK-silenced periderms suggests a role of this potato gene in RNA processing and stress
The periderm is a protective barrier crucial for land plants survival, but genetic factors involved in its regulation are fairly unknown. In a previous transcriptomic approach in the cork oak periderm (Quercus suber) we identified a RS2-INTERACTING KH PROTEIN (RIK) homolog, of unknown function and with a K homology (KH)-domain RNA-binding protein, as a regulatory candidate gene in the periderm. To gain insight into the function of RIK in periderm, the potato (Solanum tuberosum) tuber periderm was used as a model. The StRIK transcript profile showed ubiquitous accumulation in all vegetative tissues analyzed, including periderm and other suberized tissues such as root and wound-healing tissues. Downregulation of StRIK in potato by RNA interference (StRIK-RNAi) did not show evident effects in tuber periderm anatomy but unexpectedly unlike Wild type, the transgenic plants flowered. Nevertheless, the periderm of StRIK-RNAi lines did show altered expression of genes associated with RNA metabolism, stress and signaling, mirroring the biological processes found enriched within the in silico co-expression network of the Arabidopsis ortholog. Altogether those findings suggest that the potato StRIK might play roles in RNA maturation and stress response throughout diverse plant developmental processes such as flowering and periderm formation. Overall design: Sample: Tuber skin (periderm) of freshly-harvested potatoes of plants growing in soil under long-day conditions (12 h light/12 h dark)  Replicates: 3 Wild-type potato (Solanum Tuberosum) plants; 3 StRIK-RNAi transgenic line 9 potato plants, 3 StRIK-RNAi transgenic line 12 potato plants, 3 StRIK-RNAi transgenic line 47 potato plants.