Abstract:In view of the key role of NCED gene family members in regulating plant response to drought stress, this study analyzed the distribution, structure and evolution of NCED gene family from zucchini (Cucurbita pepo L.) genome by bioinformatics technology, analyzed the expression specificity of NCED gene members in different tissues and their response to simulated drought (10% PEG 6000), hormone (0.1 mmol·L-1 ABA) and natural drought (stop watering for 0, 1, 2, 3 and 4 d) stresses to understand the biological functions of NCED gene family. Experimental results show that: (1) a total of six NCED gene (i.e., CpNCED1-6) members were identified from the whole genome of zucchini; The six CpNCEDs were distributed on chromosome 1, 10, 12, 14, 19 and 20 of zucchini, and none of the NCED genes contained intron. (2) Physicochemical properties analysis showed that CpNCED1-6 proteins were 569-590 amino acids, and the theoretical molecular weight ranged from 62.64-65.54 kD. (3) Protein conserved motifs analysis showed that, the CpNCEDs containing 16 complete conserved protein motifs except for the CpNCED3 had three motifs (i.e., motif 12, motif 13 and motif 15) deletion, and CpNCED1-6 proteins conserved elements distributed within 600 amino acids, indicating most of NCED protein sequences were highly conserved. (4) The cis-acting elements analysis of NCED gene family upstream promoters (2 500 bp sequence before ATG) showed that the zucchini CpNCED1-6 genes contained potential drought stress response elements such as ABRE, W box, MBS, P-box, TCA-element, CGTCA-motif, TGA-element and TGA-box. (5) Real-time fluorescent quantitative PCR (qRT-PCR) revealed that the expression of CpNCEDs gene in different zucchini tissues was tissue specific, among which, the expression levels of CpNCED4 and CpNCED1 in stems were significantly higher than those of the other three genes, the expression levels of CpNCED2, CpNCED4 and CpNCED6 in flowers were significantly higher than those of the other three genes, and the expression level of CpNCED2 was the highest, while the expression levels of CpNCED1-6 in fruits and leaves were relatively low; The expression levels of six selected family members were induced by simulated drought, ABA hormone and natural drought stresses and increased in different degrees compared with the control group; With the emergence of drought stress, the abscisic acid (i.e., ABA) content gradually increased in leaves; This study found that six CpNCED1-6 genes played important roles in drought stress response and ABA biosynthesis of C. pepo, especially CpNCED2 and CpNCED4 genes.