Osmotic Stress Induces Rapid Activation of a Salicylic Acid–Induced Protein Kinase and a Homolog of Protein Kinase ASK1 in Tobacco Cells

Abstract

In tobacco cells, osmotic stress induced the rapid activation of two protein kinases that phosphorylate myelin basic protein. Immunological studies demonstrated that the 48-kD kinase is the salicylic acid-induced protein kinase (SIPK), a member of the mitogen-activated protein kinase family. SIPK was activated 5 to 10 min after the cells were exposed to osmotic stresses, and its activity persisted for approximately 30 min. In contrast, the 42-kD kinase was activated within 1 min after osmotic stress, and its activity was maintained for approximately 2 hr. Moreover, in addition to myelin basic protein, the 42-kD kinase phosphorylated casein and two transcription factors, c-Jun and ATF-2. This latter enzyme was inactivated by a serine/threonine-specific phosphatase but, unlike SIPK, was not affected by a tyrosine-specific phosphatase. After the 42-kD kinase was purified to apparent homogeneity, tryptic peptide analysis indicated that it is a homolog of Arabidopsis serine/threonine kinase1 (ASK1).

Cinnamic acid induced changes in reactive oxygen species scavenging enzymes and protein profile in maize (Zea mays L.) plants grown under salt stress

“…Salinity and CA altered the protein profile and was responsible for induction of several osmoresponsive genes, which may be involved in adaptation to salt stress. CA induced accumulation of proteins such as 48 and 42 kDa, have a possible role in salt adaptation and osmotic adjustment as reported by Mikolajczyk et al (2000) with salicylic acid, an analog of CA. Salicylic acid and its analog can alleviate the effect of salt stress, and improve the ability of plants to adopt salt stress.…”

Mitogen-activated protein kinase signaling in plants under abiotic stress

“…The Arabidopsis genome of a 48-kDa kinase, the SIPK (salicylic acid-induced protein kinase). 24 Osmotic stress reportedly activated the expression of AtMPK3, AtMPK4 and AtMPK6 in Arabidopsis. 25,26 Recently three salt stress-induced MAPKs, ZmMPK3, ZmMAPK5 and ZmSIMK1, have been identified in Zea mays.…”

MAPK cascades and major abiotic stresses

“…Osmotic stress also induces a rapid and transient activation of the salicylic acidinduced kinase (SIPK, an Arabidopsis MPK6 homolog in tobacco) in tobacco cells within 5-10 min (Mikolajczyk et al 2000).…”