Barley (Hordeum vulgare L.) is one of the most important cereals worldwide. Although this crop is drought-tolerant, water deficiency negatively affects its growth and production. To detect key genes involved in drought tolerance in barley, a reconstruction of the related gene network and discovery of the hub genes would help. Here, drought-responsive genes in barley were collected through analysis of the available microarray datasets (− 5 ≥ Fold change ≥ 5, adjusted p value ≤ 0.05). Protein-protein interaction (PPI) networks were reconstructed. The hub genes were identified by Cytoscape software using three Cyto-hubba algorithms (Degree, Closeness, and MNC), leading to the identification of 17 and 16 non-redundant genes at vegetative and reproductive stages, respectively. These genes consist of some transcription factors such as HvVp1, HvERF4, HvFUS3, HvCBF6, DRF1.3, HvNAC6, HvCO5, and HvWRKY42, which belong to AP2, NAC, Zinc-finger, and WRKY families. In addition, the expression pattern of four hub genes was compared between the two studied cultivars, i.e., “Yousef” (drought-tolerant) and “Morocco” (susceptible). The results of real-time PCR revealed that the expression patterns corresponded well with those determined by the microarray. Also, promoter analysis revealed that some TF families, including AP2, NAC, Trihelix, MYB, and one modular (composed of two HD-ZIP TFs), had a binding site in 85% of promoters of the drought-responsive genes and of the hub genes in barley. The identified hub genes, especially those from AP2 and NAC families, might be among key TFs that regulate drought-stress response in barley and are suggested as promising candidate genes for further functional analysis.

中文翻译：

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大麦干旱胁迫响应关键基因的新见解：基因网络重建、枢纽和启动子分析

大麦（Hordeum vulgare L.）是世界上最重要的谷物之一。虽然这种作物耐旱，但缺水对其生长和生产产生负面影响。为了检测大麦耐旱性关键基因，相关基因网络的重建和枢纽基因的发现将有所帮助。在这里，通过分析可用的微阵列数据集收集大麦中的干旱响应基因（- 5 ≥ 倍数变化 ≥ 5，调整后的 p 值 ≤ 0.05）。重建蛋白质-蛋白质相互作用（PPI）网络。通过Cytoscape 软件使用三种Cyto-hubba 算法（Degree、Closeness 和MNC）识别hub 基因，分别导致在营养和繁殖阶段识别出17 个和16 个非冗余基因。这些基因由一些转录因子组成，如 HvVp1、HvERF4、HvFUS3、HvCBF6、DRF1.3、HvNAC6、HvCO5 和 HvWRKY42，属于 AP2、NAC、锌指和 WRKY 家族。此外，还比较了两个研究品种之间四个枢纽基因的表达模式，即“Yousef”（耐旱）和“Morocco”（易感）。实时 PCR 的结果表明表达模式与微阵列确定的表达模式一致。此外，启动子分析显示，一些 TF 家族，包括 AP2、NAC、Trihelix、MYB 和一个模块（由两个 HD-ZIP TF 组成），在 85% 的干旱响应基因和大麦中的枢纽基因。确定的枢纽基因，尤其是来自 AP2 和 NAC 家族的基因，