Transcriptome analysis of apple rootstocks with different stem-root gravitropic setpoint angles.

Our objective was to study the differentially expressed genes (DEGs) of apple (Malus. sp.) rootstock with different gravitropic setpoint angles (GSAs), during the formation of stem-root GSAs. The annual shoots of eight years hybrid seedlings of Malus pumila'Ralls' and M. sp. were used as experimental materials, and softwood cutting was carried out in mid-May. Different strains of adventitious root GSA were screened and shoot cuttings were carried out again the following year. The cuttings were randomly selected at 24 day after cutting, and then the transcriptome analysis was carried out. The results show that: (1) according to the difference of stem-root GSA of cutting seedlings, the seedlings of apple rootstock were divided into 3 groups: deep root type (SC), intermediate root type (ZC) and shallow root type (QC). (2) Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that 2613 genes from shallow- and deep-rooted rootstock, 2091 from deep- and intermediate-rooted rootstock, and 3114 from intermediate- and shallow-rooted rootstock, were annotated into 125 pathways. Among these pathways, plant hormone signal transduction, biosynthesis of secondary metabolites, and phenylpropanoid biosynthesis pathways were significantly enriched (P < 0.01). [ABSTRACT FROM AUTHOR]