穿心莲不同生长发育期穿心莲内酯积累与碳氮代谢特征

Characteristics of andrographolide accumulation and carbon and nitrogen metabolisms in different growth periods of Andrographis paniculata(Burm.f.)Nees

【目的】明确穿心莲(Andrographis paniculata)不同生长发育期主要活性成分穿心莲内酯的积累和碳、氮代谢特征及其关系,为穿心莲优质高产栽培管理提供理论依据。【方法】根据穿心莲生长发育特点,将其物候期划分为塔型期、团棵期、拔节期、现蕾期、盛花期和花果期,分析大田条件下各生长发育期的生物量及穿心莲内酯积累和碳、氮代谢特征。【结果】穿心莲全株和茎秆生物量在盛花期开始稳定,叶片生物量在拔节期开始趋于稳定,相对生长速率和叶片生物量占比随着生长进程逐渐下降。叶片的穿心莲内酯含量在塔型期至现蕾期(营养生长期)逐渐上升,在现蕾期达峰值且保持稳定,单株穿心莲内酯产量在盛花期达最大。穿心莲内酯合成关键酶基因ApDXS、ApDXR、ApGGPS和ApCPS的表达量在团棵期上升,随后下降并趋于平稳,而基因ApHMGS和ApHMGR1在现蕾期后维持在高表达水平。穿心莲内酯合成可能主要受甲羟戊酸(MEP)途径调控,且穿心莲内酯积累滞后于基因表达。叶片和茎秆的氮含量随着穿心莲的生长进程逐渐下降,植株地上部氮积累量和茎秆氮积累量在现蕾期达最大值,而叶片的氮在现蕾期后向果实转移其积累量逐渐下降。塔型期和团棵期叶片氮同化相关酶中的谷氨酰胺合成酶(GS)、谷氨酸脱氢酶(NAD-GDH)和异柠檬酸脱氢酶(ICDH)活性较高,同时叶片蔗糖和可溶性总糖含量也较高,随后氮同化酶活性及蔗糖和可溶性总糖含量下降,淀粉含量的变化则相反。叶片穿心莲内酯含量和单株穿心莲内酯产量与株高、生物量、地上部氮积累量和淀粉含量呈极显著正相关(P<0.01,下同),与叶片氮含量呈极显著负相关,说明促进穿心莲营养生长期生物量积累有利于提高穿心莲内酯含量和产量。【结论】现蕾期至盛花期是采收穿心莲药材的最佳时期;营养生长期是穿心莲氮同化和积累的主要时期,在该时期适当增施氮肥促进穿心莲生物量积累可提高穿心莲内酯含量和产量。

[Objective]The present study aimed to clarify the accumulative characteristics of andrographolide,the major active component of Andrographis paniculata(Burm.f.)Nees,and carbon and nitrogen metabolism,as well as their relationship at diferent growth stages of A.paniculata,providing theoretical basis for the high-quality and high-yield cultivation management of A.paniculata.[Method]According to the growth and developmental characteristics of A.paniculata under field conditions,the phenological phase of A.paniculata was divided into six stages,tower stage,cluster stage,jointing stage,budding stage,flowering stage and fruit stage.The characteristics of biomass and andrographol-ide accumulation and carbon and nitrogen metabolisms in different growth stages were analyzed.[Result]The biomass of the whole plant and stem was stable at the flowering stage,while the biomass of leaves tended to be stable after the jointing stage.The relative growth rate and the proportion ofleaf biomass gradually decreased with the growth process.The content of andrographolide in leaves gradually increased during the tower stage-budding stage(vegetative growth period),reached the peak at the budding stage and thereafter remained stable.The yield of andrographolide per plant reached its maximum at the flowering stage.Theexpression levelsof key genes for andrographolide synthesiseg ApDXS,ApDXR,ApGGPS and ApCPS,increased at the cluster stage and then decreased and stabilized,while ApHMGS and ApHMGRI genes maintained at a high expression level after the budding stage.The synthesis of andrographolide could be mainly regulated by the mevalonate(MEP)pathway,and the accumulation of andrographolide lagged behind gene expression.The nitrogen content in leaves and stems gradually decreased with the growth of the plant,and the accumulation of nitrogen in the aboveground parts and stem reached the maximum value at the budding stage.After then,the nitrogen in leaves transferred to the fruits,resulting in gradually decreased accumulation.The activities of gluta-mine synthetase(GS),glutamate dehydrogenase(NAD-GDH),and isocitrate dehydrogenase(ICDH)in leaves were higher during the tower and cluster stages,as well as the content of sucrose and total soluble sugar in leaves.Subsequently,the activity of these enzymes and the con-tent of sucrose and total soluble sugar decreased.In contrast,starch content was increased.The content of andrographolide in leaves and the yield of andrographolide per plant were extremely significantly(P<0.01,the same as below)positively correlated with plant height,biomass,aboveground nitrogen accumulation,and starch content,but extremely significantly negatively correlated with nitrogen content in leaves,indi-cating that promoting the accumulation of biomass during the vegetative growth period of the plant was beneficial for improving the content and yield of andrographolide.[Conclusion]The optimum harvesting period for the medicinal herb of A.paniculata is from the budding stage to the flowering stage.The vegetative growth period is the main period for nitrogen assimilation and accumulation in A.paniculata.During this peri-od,increasing nitrogen fertilizer appropriately can promote the accumulation of biomass in A.paniculata,improving the content and yield of andrographolide.