Mitogen-activated protein kinase (MAPK) cascades are highly conserved signaling modules that transduce the externally perceived signals and play crucial role in plant defense against pathogen attack. In the present study, a turmeric (Curcuma longa L.) complementary DNA (cDNA) encoding a MAPK gene responsive to Pythium aphanidermatum infection was isolated using rapid amplification of cDNA ends (RACE)-PCR. It was designated as ClMPK6 based on its high homology with Arabidopsis AtMPK6. The full-length cDNA of 1484 bp length carried an open reading frame (ORF) of 1176 bp encoding a 391 amino acid polypeptide. ClMPK6 protein contains Thr-Glu-Tyr (TEY) motif on its activation loop with a common docking (CD) domain at the C-terminal end and belong to subgroup A of MAPK family. Southern hybridization revealed single copy of ClMPK6 in turmeric genome, and its intron-exon composition showed highly conserved nature of these signaling kinases across different species. Quantitative RT-PCR showed high expression of ClMPK6 in rhizome tissues of mature turmeric plants. Analysis of temporal expression revealed significant induction of ClMPK6 transcript in response to defense signaling molecules and pathogen attack at the early stages. Ectopic overexpression of ClMPK6 in Arabidopsis plants resulted in enhanced resistance to Botrytis cinerea and constitutively high expression of defense responsive genes like PDF1.2, PAD3, AOS, ACS2, ACS6, etc. Our results suggest that ClMPK6 substantiate the characteristics of AtMPK6 orthologs in defense against necrotrophic infection in plants.