Activation of a mitogen-activated protein kinase pathway is involved in disease resistance in tobacco.
Hypersensitive response (HR), a form of programmed cell death, is frequently associated with plant disease resistance. It has been proposed that mitogen-activated protein kinase ( MAPK) cascades regulate HR cell death based on pharmacological studies by using kinase inhibitors. However, direct evidence is lacking. Here, we demonstrate that NtMEK2, a MAPK kinase, is upstream of salicylic acid-induced protein kinase (SIPK) and wounding-induced protein kinase (WIPK), two tobacco MAPKs that are activated by various pathogens or pathogen-derived elicitors. Expression of a constitutively active mutant of NtMEK2 induces HR-like cell death in tobacco, which is preceded by the activation of endogenous SIPK and WIPK. In addition, NtMEK2-SIPK/WIPK cascade appears to control the expression of 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) and l-phenylalanine ammonia lyase (PAL), two defense genes encoding key enzymes in the phytoalexin and salicylic acid biosynthesis pathways. These results demonstrate that a plant MAPK cascade controls multiple defense responses against pathogen invasion.[1]References
- Activation of a mitogen-activated protein kinase pathway is involved in disease resistance in tobacco. Yang, K.Y., Liu, Y., Zhang, S. Proc. Natl. Acad. Sci. U.S.A. (2001) [Pubmed]
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