PDF(Pubmed)
Abstract：
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.
摘要：
苯并恶嗪（BXs）是玉米中独特的生物活性代谢产物，具有保护和化感特性，可响应多种胁迫。BXs的生产涉及BXs生物合成基因簇（BGC）的精细调控。然而,关于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。这里,对玉米BGC进行了系统研究，在7条染色体上鉴定出26个BGC基因成员，其中Bin4.00-4.01/4.03-4.04/7.02是最丰富的区域。所有的BX蛋白被明确地分为三类和七个亚类,在这些蛋白质中进一步鉴定了10个保守基序。这些蛋白质位于叶绿体的亚细胞区室，内质网，或者细胞质，它们的催化活性是专门执行的。三个独立的RNA测序（RNA-Seq）分析显示，大多数BGC基因成员的表达谱明显受到多种处理的影响。包括光谱质量，低温,24-表油菜素内酯诱导，和亚洲玉米虫侵扰。在三个RNA-Seq中通常检测到13个具有高和特异性表达水平的差异表达基因（DEGs），作为核心保守的BGC成员，用于在多种非生物/生物刺激下调节BXs的生物合成。此外，实时定量PCR(qRT-PCR)验证了BGC中6个核心保守基因在4种处理的幼苗叶片中显著差异表达,在黑暗和伤口处理下，导致2,4-二羟基-7-甲氧基-1,4-苯并恶嗪-3-酮（DIMBOA）含量显着增加，而在低温处理下观察到DIMBOA含量明显下降。总之,玉米中BX代谢产物的变化受多种胁迫状态下BGC基因成员的调控。因此,生物/非生物胁迫下与BX积累相关的关键基因的鉴定将为选育具有增强适应能力的玉米品种提供有价值的基因资源。
