适度紫外辐射增强对白鲜光合特性和药用活性成分的影响

Effects of moderate ultraviolet radiation enhancement on photosynthetic characteristics and medicinal active components of Dictamnus dasycarpus

关键词:  紫外辐射, 白鲜, 次生代谢, 药用成分, 光合特性

Key words:  ultraviolet radiation, Dictamnus dasycarpus, secondary metabolism, medicinal ingredients, photosynthesis characteristics

摘要:

次生代谢成分环境调控是药用植物优质栽培的理论和实践基础。然而,迄今为止,短期紫外光诱导对药用活性成分积累效应方面的研究仍然比较薄弱。该文以光环境敏感植物白鲜(Dictamnus dasycarpus)为研究对象,探索短期不同强度(低剂量和中剂量)紫外(UV)辐射增强对其根、茎和叶中黄柏酮、梣酮、白鲜碱和柠檬苦素4种有效成分的诱导效应。结果表明:(1)无论是低剂量还是中剂量UV-A和UV-B辐射条件下,白鲜叶片光系统Ⅱ(PS Ⅱ)最大光化学量子产量(F_v/F_m)均大于0.76; PS Ⅱ实际光合量子产量Y(Ⅱ)、调节性能量耗散的量子产量Y(NPQ)、基于“湖泊模型”光化学淬灭系数(qL)和非光化学淬灭系数(NPQ)与对照(未经紫外辐射处理)相比均没有显著差异; 低剂量与中剂量UV-B辐射均显著增加白鲜PS Ⅱ的非调节性能量耗散的量子产量Y(NO)。(2)适度短期紫外辐射增强能够诱导白鲜药用活性成分快速积累,根中4种有效成分最高可提升51%,主要在白鲜根中积累。其中,中剂量UV-A辐射和低剂量UV-B辐射效果最明显,不仅根中黄柏酮、梣酮、白鲜碱和柠檬苦素4种活性成分明显提升,还促进茎中白鲜碱和叶中梣酮的积累。综上所述,该研究结果表明短期紫外辐射增强能有效诱导白鲜药用活性成分的积累,并通过提升白鲜PS Ⅱ非光化学效率来提升白鲜光强耐受性。

Abstract:

The theory and practice of artificial cultivation are based on the environmental regulation of the secondary metabolism of medicinal plants. However, so far, the research on the accumulation effect of short-term ultraviolet radiation on the medicinally active ingredients was still relatively weak. In this study, the light environment-sensitive plant Dictamnus dasycarpus was taken as the research object, and the inductive effect of short-term enhanced ultraviolet radiation(UV)on four active ingredients, obacunone, fraxinellone, dictamnine, and limonin in the roots, stems, and leaves of D. dasycarpus was explored. The results were as follows:(1)Under whether low- or medium-intensity UV-A and UV-B radiation conditions, the maximum quantum yield of photosystem Ⅱ(F_v/F_m)of D. dasycarpus was always over 0.76 during the experimental period; Compared with the control(without ultraviolet radiation enhancement treatment), there was no significant differences in the actual photosynthetic quantum yield of photosystem Ⅱ Y(Ⅱ), regulated energy dissipation quantum yield Y(NPQ), photochemical quenching coefficient based “lake model”(qL)and the non-photochemical quenching coefficient(NPQ); Low- and moderate-intensity UV-B radiation significantly promoted the increase of non-regulated energy dissipation quantum yield Y(NO)of D. dasycarpus.(2)An appropriate enhanced amount of short-term ultraviolet radiation could promote the rapid accumulation of the active ingredients of D. dasycarpus, the four active ingredients in the roots could be increased by up to 51%, the accumulation was mainly in the D. dasycarpus roots. The effects of moderate intensity UV-A radiation and lower intensity UV-B radiation were the most obvious, and it not only promoted the accumulation of four active ingredients of obacunone, fraxinellone, dictamnine, and limonin in the roots, but also promoted the accumulation of dictamnine in the stems and fraxinellone in the leaves. The results reveal that the effectiveness of the accumulation of active ingredients in D. dasycarpus is improved under short-term enhanced ultraviolet radiation conditions. It also reveals that an effective way to improve the tolerance of the D. dasycarpus to light intensity and promote the accumulation of active ingredients is to increase the non-photochemical efficiency of the D. dasycarpus photosynthetic system.