Transcript profiling analysis reveals crucial genes regulating main metabolism during adventitious root formation in cuttings of Morus alba L.

Mulberry is an important economic crop spread widely in China for long time, and cutting is the most suitable method for good varieties in large scale propagation, which is limited by the low adventitious rooting rate. Currently, the regulation mechanisms in adventitious roots (AR) formation of mulberry (Morus alba L.) are not completely known. A genome-wide gene expression profiling was conducted by Solexa sequencing at pivotal stages. Differentially expressed annotated genes were obtained from the analysis of Gene Orthology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Orthology (KO). Some related genes were selected to confirm the altered expression levels by quantitative real-time PCR (qRT-PCR). By transcript profiling analysis we found differentially expressed genes associated with common pathways including hormone signal transduction, cell cycle, carbohydrate metabolism and energy metabolism that play important roles in AR formation (M. alba L), which were found more obvious in the period of root primordia formation, not initial formation of callus. In addition, the qRT-PCR confirmations agreed well with the results. The period of root primordia formation was verified to be more important during the whole procedure of AR formation in cuttings, mainly regulated by several critical signal pathways of hormones and effected by other genes in cell cycle and energy metabolism.