Abstract: WRKY transcription factors are involved in the regulation of transcriptional reprogramming associated with plant immune responses,and play a regulatory role in plant disease resistance. To identify the role of WRKY transcription factor in resistance of Cucumis metuliferus against root-knot nematode (RKN),full-length cDNA sequence of CmWRKY20 was cloned from the roots of C. metuliferus by RT-PCR combined with RACE tecnology. Two softwares of DNAStar and DNAMAN were used for amino acid sequence and phylogenetic evolutionary analyses. Tissue-specific expression characteristics and induced expression profiles of the gene were determined through qRT-PCR,and Agrobacterium-mediated transformation of tobacco leaf cells was used to investigate subcellular localization of its coding proteins. The results showed that full cDNA sequence of CmWRKY20 was 1 603 bp in length,including 5' untranslated part of 646 bp,3' untranslated part of 320 bp,an open reading frame of 1 017 bp encoding a protein of 338 amino acids consisting of a conserved WRKY domain with a nuclear localization signal and a zinc finger motif of C₂H₂,belonging to the WRKY subgroup Ⅱ. CmWRKY20 was deposited in GenBank with Accession No. MN365875,and the amino acid sequence of CmWRKY20 was highly homologous and closely related to cucumber and melon. CmWRKY20 showed higher relative expression in the resistant than the susceptible response,and higher in roots and stems than in leaves. CmWRKY20 was rapidly induced by root-knot nematode infection,salicylic acid (SA) and methyl jasmonate (MeJA) had synergistic or antagonistic effects on the expression of CmWRKY20. CmWRKY20 protein was localized on the cell membrane. CmWRKY20 may be involved in the regulation of defense response to root-knot nematode through SA/JA signal transduction.

Key words: Cucumis metuliferus, Root-knot nematodes, CmWRKY20, Cloning, Gene expression, Subcellular localization

CLC Number: 

• Q78

• S436.421