Transcriptome sequencing analysis of sorghum callus with various regeneration capacities

The applications of plant callus regeneration has been widely spreaded in agricultural improvement. By using immature sorghum embryos as explants, progress in successful genetic transformation has been made in sorghum. However, the underlying mechanism of callus differentiation is still largely unknown in sorghum. Here, we described three types of callus with different abilities of redifferentiation (Callus I-III), undergoing distinct induction from immature embryo in the variety of Hiro-1. In comparison to the non-embryonic Callus III who lost the ability of regeneration, the Callus I produced only some characterized adventitious roots and the embryonic Callus II is sufficient to regenerate whole plants. Genome-wide transcriptome profiles were performed to reveal the underlying mechenisms. The numbers of differentially expressed genes for the three types of callus vary from 5906 to 8029. Principal component analysis analysis demonstrated that gene expression patterns of Callus I and II were totally different from that of Callus III and differential leaves from Callus II, indicating that the compassions of Callus I and II provide clues for revealing regulations of regeneration in sorghum callus. Notably, KEGG and GO analysis showed that plant ribosome, lignin metabolic process, and metabolism of starch and sucrose are main processes that are associated with callus differentiation. Taken together, the results contributed the elucidation of molecular regulation in three types of callus with several regeneration abilities in sorghum. Overall design: mRNA profiles of three types of sorghum callus (namely Callus I, II and III) were generated by deep sequencing,using Illumina HiSeq.