不同光照对荞麦芽黄酮类化合物及相关代谢酶基因表达的影响

通过分析不同品种荞麦的发芽形态及发芽后总酚、总黄酮的含量，从10 个荞麦品种（7 个苦荞和3 个甜荞）中筛选出2 个最适合生产荞麦芽的品种：‘蒙古2号’苦荞和‘西农9976’甜荞。将筛选出的品种进行不同发光二极管（light-emitting diode，LED）光照发芽处理，比较荞麦芽中总酚及黄酮的含量，同时分析不同光照下苦荞芽中苯丙氨酸解氨酶、黄酮醇合酶、查耳酮合酶及查耳酮异构酶的基因表达，探讨其作用机理。结果表明，‘蒙古2号’提高黄酮类化合物含量的最佳处理方式是白光光照，其中荭草苷、异荭草苷含量分别提高了63%、69%（发芽6 d），总黄酮含量提高了40%～53%（发芽2～6 d）；‘西农9976’提高黄酮类化合物含量的最佳处理方式是红光光照，其中芦丁含量提升70%（发芽6 d），总黄酮含量最多提高111%（发芽2～6 d）。荞麦芽中总酚含量均是在红光作用下提高最多，其中‘西农9976’总酚含量最多提高83%（发芽2～6 d），且光照处理可明显上调4 种代谢酶基因的表达水平。

Effects of Different Illumination Treatments on Flavonoids and Gene Expression of Related Metabolic Enzymes in Buckwheat Sprouts

In this study, the morphology, total phenols and total flavonoids contents of buckwheat sprouts from seven tartary buckwheat cultivars and three common buckwheat cultivars were evaluated. As a result, the tartary buckwheat cultivar ‘Mongolia 2’ and the common buckwheat cultivar ‘Xinong 9976’ were selected as the most suitable for the production of buckwheat sprouts. The selected cultivars were germinated under different conditions of light-emitting diode (LED) illumination. The contents of total phenols and flavonoids in buckwheat sprouts were determined and the expression levels of the genes encoding phenylalanine synthase (PAL), flavonol synthase (FLS), chalcone synthase (CHS) and chalcone isomerase (CHI) were analyzed. Furthermore, the underlying mechanism was elucidated. It turned out that white light was identified as the optimal LED illumination for ‘Mongolia 2’, increasing the contents of orientin and isoorientin by 63% and 69% after 6-days’ of germination, respectively, and increasing total flavonoid content by 40%–53% on days 2 to 6. However, the optimal LED illumination for ‘Xinong 9976’ was red light, increasing the contents of rutin and total flavonoids by 70% and up to 111% after 6-days’ germination and on days 2 to 6, respectively. Red light was the optimal LED illumination treatment for improving the content of total phenols in buckwheat sprouts from both cultivars (by up to 83% on days 2 to 6 for ‘Xinong 9976’). Moreover, the expression levels of PAL, FLS, CHS, and CHI were significantly up-regulated in buckwheat sprouts after LED illumination treatment.