Calcium-dependent mechanism of somatic embryogenesis in Panax ginseng cell cultures expressing the rolC oncogene

The Panax ginseng 2c3 embryogenic cell culture was earlier obtained by callus cell transformation with Agrobacterium rhizogenes rolC. Calcium channel blockers (LaCl3, verapamil, and niflumic acid) reduced the production of somatic embryos in the 2c3 culture, implicating the Ca2+ signaling system in plant somatic embryogenesis. The protein kinase inhibitors W7 and H7 also decreased the yield of somatic embryos in the 2c3 culture. The total CDPK expression in the 2c3 culture was 1.2-to 1.5-fold lower than in a control callus culture as a result of a silencing of the genes belonging to the PgCDPK1 (PgCDPK1a and PgCDPK1b) and PgCDPK3 (PgCDPK3a) subfamilies. Expression of the PgCDPK2 subfamily genes (PgCDPK2b and PgCDPK2d) was increased. It was assumed that some genes of the PgCDPK1, PgCDPK2, and PgCDPK3 subfamilies were responsible for generation of embryogenic cells in the 2c3 culture. For the first time, rolC expression and embryogenesis were associated with changes in the expression of certain CDPK genes.