Transcriptomic changes in the crown (stem base) of barley (Hordeum vulgare L. cv. Golden Promise) during crown-root initiation and development

Purpose: The goal of this study was to investigate the mechanisms involved in the initiation and development of crown-roots (CRs) in barley and to estimate the role of cytokinins (CKs) in this process. Method: stranded libraries were obtained from RNA extracted from the stem base of 1 day-after-germination (DAG) and 10DAG-seedlings of wild-type (WT) and AtCKX-overexpressing barley lines (OE-CKX). OE-CKX lines have a reduced content of endogenous CKs and are characterized by a higher number of CRs. Libraries were deep sequenced on Illumina HighSeq platform. Each sample was investigated in three independent biological replicates. Results: Using a data analysis workflow optimized for barley, we identified more than 4000 transcripts differentially expressed in the stem base of 1DAG and 10DAG-seedlings. Expression as determined by RNA-seq was validated by real-time PCR. Our data were compared to the transcriptomic profiling obtained from rice and we were able to identify genes potentially involved in the initiation/development of CRs in barley. Also the use of the transgenic line with altered endogenous CK content allowed us to conclude about the role of CKs in the process. Conclusions: Our study represents the first analysis aiming to understand the initiation and development of CRs in barley. Overall design: mRNA profiles of stem base of 1 day-after-germination (DAG) and 10DAG seedling were generated by deep sequencing, in triplicate, using Illumina HighSeq the analysis was performed on wild-type (WT) as well as on AtCKX1-overexpressing lines, accumulating lower amount of cytokinins