Abstract: 【Objective】The main producing areas of maize is mostly located on the arid or semi-arid region that relying on the rainfed farming in China. The maize production losses caused by drought is a great threaten to food security. As a cross-pollinating crop, maize is mostly sensitive to water stress during flowering time. Drought at flowering stage will lead to asynchronous development between the male and female flower and cause massive grain yield loss. Thus, mining drought resistance related genes at flowering stage is important for maize drought resistance improvement and breeding. 【Method】In the present study, the phylogenic tree of 24 ZCN genes in maize genome, which is homologs of Arabidopsis FT gene, was build. The gene expression patterns of ZCN7 were analysis using qRT-PCR and in vivo GFP fluorescence imaging. A maize natural population consisting of 118 diverse inbred lines were planted in three environments, Beijing in 2021 and 2022 and Urumqi in 2022, to identify the flowering time related traits under different water treatments. The genomic variants around ZCN7 were detected by PCR and Sanger sequencing. The candidate gene association analysis was performed based on mixed linear model and the significant associated variants with drought induced anthesis-silking interval was obtained. The gene expression level of ZCN7 in natural population at flowering time was also measured by qRT-PCR. The differences of drought resistance traits and ZCN7 expression were compared between different haplotypes of significant associated variant. The Ubi1:ZCN7 overexpression transgenic maize were obtained, and the phenotypic performance was identified under different water treatments. 【Result】The 24 ZCN genes in maize genome included 15 FT like genes, 6 TFL1 like genes and 3 MFT like genes. The protein sequence of ZCN genes varied from 111 nn to 193 nn. The ZCN7 showed close relationship with ZCN8 and the protein sequence identity was 83.3% between the two genes. ZCN7 showed highest gene expression in the leaf blade at V12 stage. And the ZCN7-promoter:GFP vector was transformed to Arabidopsis and the GFP showed enriched signal at the blade edge of mature leaf. The candidate gene association analysis revealed a SNP variant at 1001 bp upstream of ZCN7 start codon had highest association signal with drought induced anthesis-silking interval under drought. The A/A and G/G haplotypes of SNP-1001 included 78 and 27 inbred lines, respectively. The anthesis-silking interval of A/A haplotype lines were significantly lower than G/G lines. And the ZCN7 gene expression of A/A haplotype lines were significantly higher than G/G lines. In addition, the ZCN7 overexpression transgenic lines showed significantly decreased anthesis-silking interval than wild type lines. Under drought, the anthesis-silking intervals of OE1 and OE2 were 2.3 and 2.6 days shorter than wild type lines. And the grain yield per plant and kernel number per plant of transgenic lines were significantly higher than wild type lines under drought, while the hundred kernel wight, kernel length and kernel width showed no significant difference. 【Conclusion】The maize ZCN7 played positive role in drought resistance and its overexpression improved grain yield by reducing anthesis-silking interval under drought.

Key words: maize (Zea mays L.), drought resistance, flowering time, ZCN