The clade A members of serine/threonine protein phosphatase 2Cs (PP2Cs) play crucial roles in plant growth, development, and stress response via the ABA signaling pathway. But little is known about other PP2C clades in plants. Our previous study showed that maize the ZmPP2C26, a clade B member of ZmPP2Cs, negatively regulated drought tolerance in transgenic Arabidopsis. However, the upstream regulatory mechanism of ZmPP2C26 remains unclear. In the present study, the expression of ZmPP2C26 gene in maize was analyzed by quantitative real time PCR (qRT-PCR). The results showed that the expression of ZmPP2C26 in shoot and root was both significantly inhibited by drought stress. Subsequently, a 2175 bp promoter of ZmPP2C26 was isolated from maize genome (P₂₁₇₅). To validate whether the promoter possess some key cis-element and negatively drive ZmPP2C26 expression in drought stress, three 5´-deletion fragments of 1505, 1084 and 215 bp was amplified from P₂₁₇₅ and were fused to β-glucuronidase (GUS) and luciferase gene (LUC) to produce promoter::GUS and promoter::LUC constructs, and transformed into tobacco, respectively. Transient expression assays indicated that all promoters could drive GUS and LUC expression. The GUS and LUC activity were both significantly inhibited by PEG-6000 treatment. Notably, the − 1084 to − 215 bp promoter possess one MBS element and inhibits the expression of GUS and LUC under drought stress. Meanwhile, we found that the 215 bp length is enough to drive ZmPP2C26 expression. These findings will provide insights into understanding the transcription-regulatory mechanism of ZmPP2C26 negatively regulating drought tolerance.

丝氨酸/苏氨酸蛋白磷酸酶 2Cs (PP2Cs) 的进化枝 A 成员通过 ABA 信号通路在植物生长、发育和胁迫反应中起关键作用。但对植物中的其他 PP2C 进化枝知之甚少。我们以前的研究表明，玉米ZmPP2C26，的B亚型成员ZmPP2Cs转基因，负调节耐旱性拟南芥。然而，ZmPP2C26的上游调控机制仍不清楚。在本研究中，ZmPP2C26基因在玉米中的表达通过实时定量 PCR (qRT-PCR) 进行分析。结果表明，ZmPP2C26的表达干旱胁迫显着抑制了地上部和根系。随后，从玉米基因组( P ₂₁₇₅ )中分离到ZmPP2C26的2175bp启动子。为了验证启动子是否具有一些关键的顺式元件并在干旱胁迫下负驱动ZmPP2C26表达，从P ₂₁₇₅扩增了1505、1084和 215 bp 的三个 5´-缺失片段，并与 β-葡萄糖醛酸酶 ( GUS ) 和荧光素酶融合基因 ( LUC ) 产生启动子::GUS和启动子::LUC构建体，并分别转化为烟草。瞬时表达分析表明所有启动子都可以驱动GUS和LUC表达。PEG-6000 处理显着抑制了 GUS 和 LUC 活性。值得注意的是，- 1084 至- 215 bp 的启动子具有一个 MBS 元件并在干旱胁迫下抑制GUS和LUC的表达。同时，我们发现 215 bp 的长度足以驱动ZmPP2C26表达。这些发现将为理解ZmPP2C26负调节耐旱性的转录调节机制提供见解。