Isolation, Identification and Response to Abiotic Stress of CpWRKY2 Gene in Cucurbita pepo

Abstract:

In order to understand the function of WRKY2 in zucchini (Cucurbita pepo), a length of 1 071 bp cDNA, named CpWRKY2 (GenBank accession No. XM_023676898.1), was isolated from leaves by using transcriptome sequencing technology (i.e. RNA-seq). The cDNA contains an 840 bp open reading frame (ORF) encoding 279 amino acids. The nucleotide sequence of ORF was sharing over 98.51% with that from Cucurbita moschata (GenBank accession No.: XM_023091218.1), indicating a highly conservative evolution. CpWRKY2 protein was located in the nucleus, containing a conserved WRKY domain (position 201-267), a WRKY DNA binding domain (position 206-266), a zinc finger domain (position 232-264) of the C₂H₂ type, and a conserved RTGHARFRRAP (positions 76-86) amino acid sequence, which belonged to the typical IId subclass WRKY family proteins. The upstream promoter region of CpWRKY2 gene (1 513 bp before ATG) contained possible stress response cis-acting elements, such as ARE, ABRE, MBS, TC-rich repeat, and W-box. CpWRKY2 expression had tissue specificity, which was the highest in flowers, followed by roots and stems, and the lowest in leaves and fruits. Moreover, the expression of CpWRKY2 was overall up-regulated under stresses, such as 5 ℃, 10% PEG 6000, 0.1 mmol/L ABA, 50 mmol/L ETH, 10 mmol/L SA, and 50 mmol/L MeJA, suggesting CpWRKY2 gene might be involved in defense response to different abiotic stresses of C. pepo.