Ye Zhangqin, Zhang Jing, Tian Xin, Yang Zhengfei, Zhu Jiangyu, Yin Yongqi
College of Food Science and Engineering, Yangzhou University, Yangzhou 225009, China.
Plants (Basel). 2025 Jul 16;14(14):2201. doi: 10.3390/plants14142201.
Finger millet ( L.) is a nutrient-dense cereal with high flavonoid content, yet the mechanisms regulating its secondary metabolite biosynthesis remain underexplored. Various exogenous stimuli can readily activate the enzymatic pathways and gene expression associated with flavonoid biosynthesis in plants, which are regulated by developmental cues. Research has established that methyl jasmonate (MeJA) application enhances secondary metabolite production in plant systems. This investigation examined MeJA's influence on flavonoid accumulation and physiological responses in finger millet sprouts to elucidate the molecular mechanisms underlying MeJA-mediated flavonoid accumulation. The findings revealed that MeJA treatment significantly suppressed sprout elongation while enhancing the biosynthesis of total flavonoids and phenolic compounds. MeJA treatment triggered oxidative stress responses, with hydrogen peroxide and superoxide anion concentrations increasing 1.84-fold and 1.70-fold compared to control levels at 4 days post-germination. Furthermore, the antioxidant defense mechanisms in finger millet were upregulated following treatment, resulting in significant enhancement of catalase and peroxidase enzymatic activities and corresponding transcript abundance. MeJA application augmented the activities of key phenylpropanoid pathway enzymes-phenylalanine ammonia-lyase (PAL) and cinnamate 4-hydroxylase (C4H)-and upregulated their respective gene expression. At 4 days post-germination, and transcript levels were elevated 3.67-fold and 2.61-fold, respectively, compared to untreated controls. MeJA treatment significantly induced the expression of downstream structural genes and transcriptional regulators. This study provides a deeper understanding of the mechanism of flavonoid accumulation in foxtail millet induced by MeJA, and lays a foundation for exogenous conditions to promote flavonoid biosynthesis in plants.
龙爪稷（L.）是一种营养丰富的谷物，黄酮类化合物含量高，但其次生代谢物生物合成的调控机制仍未得到充分探索。各种外源刺激可以很容易地激活与植物黄酮类生物合成相关的酶促途径和基因表达，这些途径受发育线索调控。研究表明，施用茉莉酸甲酯（MeJA）可提高植物系统中次生代谢物的产量。本研究考察了MeJA对龙爪稷芽中黄酮类物质积累和生理反应的影响，以阐明MeJA介导黄酮类物质积累的分子机制。研究结果表明，MeJA处理显著抑制了芽的伸长，同时增强了总黄酮和酚类化合物的生物合成。MeJA处理引发了氧化应激反应，发芽后4天，过氧化氢和超氧阴离子浓度分别比对照水平增加了1.84倍和1.70倍。此外，处理后龙爪稷的抗氧化防御机制上调，导致过氧化氢酶和过氧化物酶的酶活性及相应转录本丰度显著增强。施用MeJA增强了关键苯丙烷途径酶——苯丙氨酸解氨酶（PAL）和肉桂酸4-羟化酶（C4H）的活性，并上调了它们各自的基因表达。在发芽后4天，与未处理的对照相比， 和 转录水平分别提高了3.67倍和2.61倍。MeJA处理显著诱导了下游结构基因和转录调节因子的表达。本研究为深入了解MeJA诱导谷子黄酮类物质积累的机制奠定了基础，并为外源条件促进植物黄酮类生物合成提供了依据。
