Abstract
Cultured cell line, GTH4, of Nicotiana gossei x N. tabacum which showed hybrid lethality at seedling stage, induces cell death at 26 C, but not at 37 C. The cell death was promoted by Okadaic acid and Calyculin A, inhibitors of serine/threonine protein phosphatase, while suppressed by the protein kinase inhibitor Staurosporine. Phosphorylation of salicylic acid-induced protein kinase (SIPK), a type of mitogen-activated protein kinase (MAPK), was detected by anti-ACTIVE MAPK antibody in the GTH4 cells after transfer the cells from 37 C to 26 C. The U0126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene), a specific inhibitor of MAPK kinase which is upstream of MAPK, strongly reduced both phosphorylation level of the SIPK and cell death. The inhibitor also suppressed the temporal generation of hydrogen peroxide that was implicated in the death of hybrid cells. These results suggested that activation of MAPK pathway provoke death of the hybrid cells through induction of oxidative burst.
