Hybrid Lethality in Interspecific F 1 Hybrid Nicotiana gossei × N. tabacum Involves a MAP‐Kinases Signalling Cascade

• Published in: Plant biology (Stuttgart, Germany) Germany), 2007-05, Vol.9 (3), p.366-373
• Main Authors: Mino, M., Kubota, M., Nogi, T., Zhang, S., Inoue, M.
• Format: Article
• Language: English
• ISSN: 1435-8603; 1438-8677
• DOI: 10.1055/s-2006-924725

A cultured cell line, GTH4 ( Nicotiana gossei Domin × N. tabacum L.), which exhibits hybrid lethality, died at 26 °C, but not at 37 °C. Pharmacological experiments using inhibitors of protein phosphatases and protein kinases indicated the involvement of a protein kinase signalling pathway in the cell death process. Immunoblot analysis revealed that salicylic acid‐induced protein kinase (SIPK) was phosphorylated soon after the shift in temperature from 37 °C to 26 °C. Cultured cells of the hybrid of N. gossei × transgenic N. tabacum harboring a steroid (dexamethasone; DEX)‐inducible NtMEK2 DD or NtMEK2 KR , constitutively active and inactive forms of NtMEK2, respectively, were established. Induction of NtMEK2 DD by DEX in the hybrid cells induced the activation of SIPK, the generation of hydrogen peroxide (H 2 O 2 ), and cell death at 37 °C. The activation of SIPK, generation of H 2 O 2 , and cell death at 26 °C were compromised by DEX treatment in hybrid cells harbouring NtMEK2 KR . This study provides evidence for the involvement of MAPK signalling in the regulation of cell death in hybrids.