Maintenance of energy metabolism is critical for rice (Oryza sativa) tolerance under submerged cultivation. Here, OsHXK7 was the most actively induced hexokinase gene in the embryos of hypoxically germinating rice seeds. Suspension-cultured cells established from seeds of T-DNA null mutants for the OsHXK7 locus did not regrow after 3-d-hypoxic stress and showed increased susceptibility to low-oxygen stress—in terms of viability—and decreased alcoholic fermentation activities compared to those of the wild-type. The promoter element containing the TGACG-motif, a well-known target site for the basic leucine zipper (bZIP) transcription factors, was responsible for sugar regulation of the OsHXK7 promoter activity. Systematic screening of the OsbZIP genes showing the similar expression patterns to that of OsHXK7 in the transcriptomic datasets produced two bZIP genes, OsbZIP38 and 87, belonging to the S₁ bZIP subfamily as the candidate for the activator for this gene expression. Gain- and loss-of-function experiments through transient expression assays have demonstrated that these two bZIP proteins are indeed involved in the induction of OsHXK7 expression under starvation or low-energy conditions. Our finding suggests that C/S₁ bZIP network-mediated hypoxic deregulation of sugar-responsive genes may work in concert for the molecular adaptation of rice cells to submergence.

维持能量代谢对于水稻 ( Oryza sativa ) 水下栽培的耐受性至关重要。在此，OsHXK7是缺氧发芽水稻种子胚胎中最活跃诱导的己糖激酶基因。由OsHXK7基因座的 T-DNA 无效突变体种子建立的悬浮培养细胞在 3 天缺氧胁迫后不会重新生长，并且与那些细胞相比，在活力方面对低氧胁迫的敏感性增加，并且酒精发酵活性降低野生型的。含有 TGACG 基序的启动子元件是众所周知的碱性亮氨酸拉链 (bZIP) 转录因子的靶位点，负责OsHXK7启动子活性的糖调节。对转录组数据集中显示与OsHXK7相似表达模式的OsbZIP基因进行系统筛选，产生了两个 bZIP 基因OsbZIP38和 87，属于 S ₁ bZIP 亚家族，作为该基因表达激活剂的候选基因。通过瞬时表达测定进行的功能获得和功能丧失实验表明，这两种 bZIP 蛋白确实参与了饥饿或低能量条件下OsHXK7表达的诱导。我们的研究结果表明，C/S ₁ bZIP 网络介导的糖反应基因的缺氧失调可能与水稻细胞对淹没的分子适应协同作用。