Expression profiling of a novel calcium-dependent protein kinase gene, LeCPK2, from tomato (Solanum lycopersicum) under heat and pathogen-related hormones

Abstract

A full-length cDNA LeCPK2 (GenBank GQ205414) from tomato (Solanum lycopersicum) encoding a calcium- dependent protein kinase (CDPK) was cloned by in silico cloning using NtCPK5 (AY971376) as a virtual probe. The deduced amino acid sequence of LeCPK2 contained the kinase, autoinhibitory, and calmodulinlike domains typical of CDPKs. Expression profiling indicated that LeCPK2 expressed predominantly in flowers and responded divergently to heat and cold stress, in which obvious mRNA accumulation was detected at 4 h under 42°C stress, but no change in LeCPK2 mRNA levels was observed in 6 h at 4°C. Mechanical wounding and phytohormones including ethylene, methyl jasmonate, and salicylic acid were also observed to arouse the expression of LeCPK2 in a similar pattern. mRNA accumulation was enhanced at 30 min and reached a maximum at 3 h, followed by a decrease to the normal level. All the results suggest that LeCPK2 is a novel versatile isoform of tomato CDPKs.