RNA sequencing of citrus callus

Gene expression profiles in response to miR171 overexpression during SE were revealed by comparative transcriptomic analysis of a miR171 overexpression callus line (OE L21) relative to WT at 0, 29, 39 and 59 days after somatic embryos induction (DAI), before the appearance of globular embryoids. The OE callus stayed as white and friable as WT callus from 0 to 29 DAI, till it turned to light yellow color at 39 DAI, and became granulated with spherical granule appeared subsequently at 59 DAI. Large quantities of green globular-shaped embryoids were visible in the OE callus at 70 DAI. In contrast, WT G1 callus generated null somatic embryos during induction. A total of 6,491 DEGs were identified between the OE line and WT at the four sampling stages. Our result indicated that overexpression of miR171 activated the expression of many SE-related genes in citrus callus, which may provide a favorable physiological and molecular basis for somatic-to-embryogenic cell fate transition and totipotency acquisition.