钾对兰州百合鳞茎中多酚类物质积累代谢及其抗氧化活性的影响

为探究施钾对兰州百合鳞茎中多酚类物质的积累、抗氧化能力及差异代谢物的影响,该研究以兰州百合鳞茎为试材,通过固定氮素(N)和磷素(P)用量,设置不同钾(K)浓度处理,即K_(0)(不施肥)、K_(1)(447.6 mg·L^(-1))、K_(2)(671.4 mg·L^(-1))、K_(3)(895.2 mg·L^(-1)),采用福林-肖卡法、溴甲酚绿比色法、香草醛比色法、DPPH法、铜离子还原能力(CUPRAC)法测定不同K浓度处理下兰州百合鳞茎中多酚类物质含量及其抗氧化活性,并采用LC-MS法分析多酚类物质的差异代谢物,并进行差异代谢物筛选,功能注释及富集分析,为兰州百合的优质栽培提供理论依据。结果表明:(1)不同K浓度处理下兰州百合鳞茎中多酚类物质的含量及其抗氧化活性存在显著差异(P<0.05),与K_(0)相比,K_(1)、K_(2)、K_(3)均能促进鳞茎多酚类物质的积累及其抗氧化能力的提高,其中以K_(2)(671.4 mg·L^(-1))效果最佳。(2)相关性分析表明,兰州百合鳞茎多酚类物质含量与抗氧化活性指标呈极显著(P<0.01)相关关系,相关系数为0.451~0.959。(3)K_(0)、K_(2)浓度处理下兰州百合鳞茎中存在89种多酚类及相关化合物,其中52种相对含量显著上调,37种相对含量显著下调,且显著富集到黄酮类及苯丙类化合物生物合成的通路上。研究认为,兰州百合的最佳施钾量(671.4 mg·L^(-1))能有效促进鳞茎中多酚类物质的积累并提高其抗氧化能力。

Effects of Potassium on Accumulation and Metabolism of Polyphenols and Antioxidant Activity in Bulbs of Lilium davidii var. unicolor

To investigate the effects of potassium application on the accumulation of polyphenols, antioxidative capacity and differential metabolites in bulbs of Lilium davidii var. unicolor, this study experimented with bulbs of L. davidii var. unicolor and used fixed application amounts of N and P, and different treatment levels of K (K₀, 0 mg·L^-1; K₁, 447.6 mg·L^-1; K₂, 671.4 mg·L^-1; and K₃, 895.2 mg·L^-1) to determinate the polyphenol contents and the antioxidative effects in bulbs of L. davidii var. unicolor at varying K concentrations through the use of the foline ciocalteu colorimetric method, the aluminum chloride colorimetric assay, the vanillin colorimetric method, DPPH method, and CUPRAC method. We also analyzed the differential metabolites of polyphenols by LC-MS, and performed differential metabolite screening, functional annotation and enrichment analysis to provide a theoretical basis for the quality cultivation of L. davidii var. unicolor. The main findings were shown as follows: (1) there were significant difference in the contents of polyphenols and antioxidative activity in bulbs under different K concentrations (P<0.05); compared with K₀, the K levels at K₁, K₂, and K₃ could promote the accumulation of polyphenols and the antioxidative capacity of bulbs, where K₂ (671.4 mg·L^-1) had the best effect. (2) Correlation analysis showed that the content of polyphenolic substances in bulbs of L. davidii var. unicolor was highly significantly (P<0.01) correlated with the index of antioxidant activity, with correlation coefficients ranging from 0.451 to 0.959. (3) There were 89 types of polyphenols and related compounds identified in bulbs of L. davidii var. unicolor treated at K₀ and K₂ concentrations, among which 52 types of polyphenols had significantly up-regulated relative contents while 37 had significantly down-regulated relative contents, which were significantly enriched in flavonoids and phenylpropanoids biosynthetic pathways. It was concluded that the optimal potassium application rate (671.4 mg·L^-1) of L. davidii var. unicolor could effectively promote the accumulation of polyphenols in the bulbs and improve their antioxidant capacity.