NADPH氧化酶(NADPH oxidases，NOXs)是植物活性氧产生的重要酶类，在生长发育及逆境响应中具有重要作用。为阐明甜瓜(Cucumis melo L.)NOX基因家族的序列特征及其低温响应模式，本研究利用生物信息学分析、RNA-seq转录组测序和RT-qPCR技术，对甜瓜NOX家族成员进行了全基因组水平的鉴定与表达模式分析。结果表明，甜瓜基因组中共鉴定出8个NOX成员，分布在6条染色体上，均含有Ferric_reductase、FAD_binding_8、NAD_binding_6和NADPH_Ox等保守结构域，蛋白整体呈碱性亲水特征。系统发育分析将NOX蛋白划分为5个亚组；共线性分析显示，甜瓜种内仅存在1对复制基因，且受到纯化选择作用。启动子区域含有多种激素和逆境响应相关顺式作用元件，其中CmNOX2和CmNOX4含低温响应元件。4℃处理24 h和48 h后，叶片相对离子渗透率由28.33%分别提升至42.67%和52.67%；通过转录组分析分别鉴定出5,633个和6,882个差异表达基因。冷响应相关基因呈明显差异表达，其中SLAC1和CPK19的表达持续上调。RT-qPCR结果显示，CmNOX2、CmNOX5、CmNOX6和CmNOX7在低温处理后表达量显著下调，而CmNOX4在48 h表达量极显著上调。综合启动子元件和表达特征，CmNOX4可能是参与甜瓜低温响应的重要候选基因。本研究系统解析了甜瓜NOX基因家族的结构、进化及表达特征，筛选出低温响应候选基因，为进一步研究甜瓜低温适应机制提供了参考。

NADPH oxidases (NOXs) are crucial enzymes for reactive oxygen species (ROS) generation in plants and play vital roles in growth, development, and stress responses. To elucidate the sequence characteristics of the NOX gene family and its low-temperature response patterns in melon (Cucumis melo L.), this study conducted genome-wide identification and expression profiling of NOX family members using bioinformatics analysis, RNA-seq transcriptome sequencing, and real-time quantitative PCR (RT-qPCR). The results revealed that eight NOX members were identified in the melon genome, distributed across six chromosomes. All members harbored conserved domains including Ferric_reductase, FAD_binding_8, NAD_binding_6, and NADPH_Ox, and the encoded proteins were generally basic and hydrophilic. Phylogenetic analysis classified the NOX proteins into five subgroups. Synteny analysis indicated the presence of only one pair of intraspecific duplicated genes in melon, which was under purifying selection. The promoter regions contained multiple hormone- and stress-responsive cis-acting elements, with CmNOX2 and CmNOX4 harboring low-temperature responsive elements. Following treatment at 4℃ for 24 h and 48 h, leaf relative electrolyte leakage (REL) increased from 28.33% to 42.67% and 52.67%, respectively; transcriptome analysis identified 5,633 and 6,882 differentially expressed genes (DEGs), respectively. Cold-responsive genes exhibited significant differential expression, with SLAC1 and CPK19 showing sustained upregulation. RT-qPCR results demonstrated that the expression of CmNOX2, CmNOX5, CmNOX6, and CmNOX7 was significantly downregulated after low-temperature treatment, whereas CmNOX4 expression was significantly upregulated at 48 h. Integrating promoter elements and expression characteristics, CmNOX4 may represent an important candidate gene involved in melon low-temperature response. This study systematically characterized the structure, evolution, and expression patterns of the melon NOX gene family, identified candidate genes responsive to low temperature, and provides a reference for further investigation into the mechanisms underlying melon cold adaptation.