State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China.
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2024 Jul 7;25(13):7460. doi: 10.3390/ijms25137460.
Benzoxazinoids (BXs) are unique bioactive metabolites with protective and allelopathic properties in maize in response to diverse stresses. The production of BXs involves the fine regulations of BXs biosynthetic gene cluster (BGC). However, little is known about whether and how the expression pattern of BGC members is impacted by biotic and abiotic stresses. Here, maize BGC was systemically investigated and 26 BGC gene members were identified on seven chromosomes, for which Bin 4.00-4.01/4.03-4.04/7.02 were the most enriched regions. All BX proteins were clearly divided into three classes and seven subclasses, and ten conserved motifs were further identified among these proteins. These proteins were localized in the subcellular compartments of chloroplast, endoplasmic reticulum, or cytoplasmic, where their catalytic activities were specifically executed. Three independent RNA-sequencing (RNA-Seq) analyses revealed that the expression profiles of the majority of BGC gene members were distinctly affected by multiple treatments, including light spectral quality, low-temperature, 24-epibrassinolide induction, and Asian corn borer infestation. Thirteen differentially expressed genes (DEGs) with high and specific expression levels were commonly detected among three RNA-Seq, as core conserved BGC members for regulating BXs biosynthesis under multiple abiotic/biotic stimulates. Moreover, the quantitative real-time PCR (qRT-PCR) verified that six core conserved genes in BGC were significantly differentially expressed in leaves of seedlings upon four treatments, which caused significant increases in 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) content under darkness and wound treatments, whereas a clear decrease in DIMBOA content was observed under low-temperature treatment. In conclusion, the changes in BX metabolites in maize were regulated by BGC gene members in multiple stress presences. Therefore, the identification of key genes associated with BX accumulation under biotic/abiotic stresses will provide valuable gene resources for breeding maize varieties with enhanced capability to adapt to environmental stresses.
苯并恶嗪类（BXs）是玉米中具有保护和化感特性的独特生物活性代谢物，可响应多种胁迫。BXs 的产生涉及 BXs 生物合成基因簇（BGC）的精细调控。然而，人们对于 BGC 成员的表达模式是否以及如何受到生物和非生物胁迫的影响知之甚少。在这里，我们系统地研究了玉米 BGC，并在 7 条染色体上鉴定了 26 个 BGC 基因成员，其中 Bin 4.00-4.01/4.03-4.04/7.02 是最富集的区域。所有 BX 蛋白都明显分为 3 类和 7 个亚类，并在这些蛋白中进一步鉴定了 10 个保守基序。这些蛋白定位于叶绿体、内质网或细胞质的亚细胞区室，在这些区室中执行其催化活性。3 个独立的 RNA 测序（RNA-Seq）分析表明，大多数 BGC 基因成员的表达谱受到多种处理的明显影响，包括光质、低温、24-表油菜素内酯诱导和亚洲玉米螟侵害。在三个 RNA-Seq 中，普遍检测到 13 个差异表达基因（DEG），它们具有高且特异的表达水平，这些基因被认为是在多种非生物/生物刺激下调节 BXs 生物合成的核心保守 BGC 成员。此外，定量实时 PCR（qRT-PCR）验证了 BGC 中的 6 个核心保守基因在 4 种处理下幼苗叶片中的表达水平显著不同，这导致黑暗和伤口处理下 2,4-二羟基-7-甲氧基-1,4-苯并恶嗪-3-酮（DIMBOA）含量显著增加，而低温处理下 DIMBOA 含量明显减少。总之，在多种胁迫存在下，玉米中 BX 代谢物的变化受 BGC 基因成员的调节。因此，鉴定与生物/非生物胁迫下 BX 积累相关的关键基因将为培育具有增强适应环境胁迫能力的玉米品种提供有价值的基因资源。
