Comparative transcriptome analysis reveals molecular regulators underlying pluripotent cell induction and callus formation in Anthurium andraeanum “Alabama”

Shoot regeneration from pluripotent cell masses is an important process for genetic improvement of Anthurium andraeanum through Agrobacterium-mediated transformation. However, the mechanisms underlying pluripotent cell induction are not well understood. Here, three half-leaf explant samples collected after 0-, 2-, and 30-d culture on callus-inducing medium were used for RNA isolation and transcriptome profiling. In total, 225,752 non-redundant unigenes were assembled with a mean length of 1299 bp. Differentially expressed genes among the three samples were identified by comparative transcriptome analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed the greatest number of differentially expressed genes in the comparison between 0- and 2-d cultures were related to the “ribosome.” Many differentially expressed genes in the comparison between 2- and 30-d cultures were involved in “plant hormone signal transduction,” “starch and sucrose metabolism,” and “phenylpropanoid biosynthesis.” Further investigation was focused on genes related to transcription factors, epigenetic regulation, nitrous oxide metabolism, and homeostasis of plant hormones auxin, cytokinin, brassinolide, and strigolactone. Experiments were designed to confirm the effects of nitrous oxide and strigolactone on callus formation in Anthurium andraeanum. Callus formation was enhanced by exogenous application of sodium nitroprusside, which produces nitrous oxide, but was inhibited under rac-GR24 (a strigolactone analogue) treatment. Our comparative transcriptome analysis revealed that the signal molecule nitrous oxide and plant hormones auxin, cytokinin, and brassinolide act as positive regulators in promoting callus formation, while strigolactone may inhibit callus formation. Transcriptional and epigenetic regulations also play important roles in pluripotent cell induction in Anthurium andraeanum.