叶面喷施丝氨酸缓解三七热胁迫机制初探

Preliminary Study on the Mechanism of Foliar Spraying of Serine to Alleviate Heat Stress in Panax notoginseng

【目的】探索叶面喷施丝氨酸对三七热胁迫的缓解效应及潜在机制。【方法】室内利用光照培养箱设置36℃高温处理盆栽三七15 d,期间每2 d分别喷施1次1、3和5 mmol/L的丝氨酸溶液,处理结束后调查三七病叶率。在田间利用自然高温环境胁迫三七,每3 d分别喷施1次与室内相同浓度的丝氨酸溶液,胁迫时间延长至30 d,调查三七病叶率以及高温对三七生物量和皂苷含量的影响。测定室内盆栽的三七抗氧化酶活性及代谢物含量变化,阐释丝氨酸缓解三七热胁迫的初步机制。【结果】喷施3和5 mmol/L丝氨酸可显著降低盆栽三七病叶率(P<0.05);1、3和5 mmol/L丝氨酸均可显著降低田间三七病叶率(P<0.05),增加其单株干质量以及人参皂苷Rg_(1)、Re、Rb_(1)和Rd含量。1和3 mmol/L丝氨酸可显著提高盆栽三七叶片超氧化物歧化酶(SOD)活性(P<0.05),3 mmol/L丝氨酸可显著提高其过氧化物酶(POD)活性(P<0.05)。KEGG富集分析表明:丝氨酸处理后一些非酶抗氧化代谢物如糖醇和氨基酸在叶片中大量积累;与植物耐热性相关的糖类物质如蔗糖和海藻糖积累量增加;三羧酸循环中重要代谢产物如柠檬酸、乌头酸和琥珀酸的积累也增加,有助于改善三七的能量供应。【结论】外源喷施丝氨酸能降低热胁迫下三七病叶率,提高三七生物量和皂苷积累,初步认为其机制与提高三七的抗氧化能力以及增强碳水化合物代谢相关。

[Purpose]To explore the alleviating effect and potential mechanism of foliar spraying serine on heat stress of Panax notoginseng.[Methods]Indoor potted P.notoginseng plants were subjected to a 36℃high-temperature treatment for 15 days using a light incubator.During the treat-ment period,serine solutions with concentrations of 1,3 and 5 mmol/L were sprayed every two days,and the rate of diseased leaves of P.notoginseng was investigated at the end of treatment.In the field,P.notoginseng was exposed to natural high-temperature conditions,and serine solution with the same concentrations as used indoors were sprayed every three days.The duration of the heat stress treat-ment was extended to 30 days,the rate of diseased leaves of P.notoginseng and the effects of high temperature on the biomass and saponin content of P.notoginseng were examined.Antioxidant en-zyme activity and metabolite changes in indoor potted P.notoginseng plants were measured to elucid-ate the preliminary mechanism by which serine alleviates heat stress in P.notoginseng.[Results]Spraying serine at concentrations of 3 and 5 mmol/L significantly reduced the rate of dis-eased leaves in potted P.notoginseng(P<0.05).Spraying 1,3,and 5 mmol/L serine significantly re-duced the rate of diseased leaves in field-grown P.notoginseng plants(P<0.05),and increased the dry weight of per plant as well as the content of ginsenosides Rg_(1),Re,Rb_(1),and Rd.Spraying 1 and 3 mmol/L serine significantly increased the activity of superoxide dismutase(SOD)in potted P.noto-ginseng leaves(P<0.05),while spraying 3 mmol/L serine significantly increased peroxidase(POD)activity(P<0.05).KEGG enrichment analysis showed that non-enzymatic antioxidant metabolites such as sugar alcohols and amino acids accumulated in large amounts in the leaves after serine treat-ment.The accumulation of heat stress-related carbohydrates such as sucrose and trehalose also in-creased.In addition,important metabolites in the tricarboxylic acid cycle such as citric acid,aconitic acid,and succinic acid showed increased accumulation,which contributed to improve energy supply in P.notoginseng.[Conclusion]Exogenous foliar application of serine reduces the incidence of diseased leaves,increases biomass,and enhances saponin accumulation in P.notoginseng under heat stress.These effects are likely associated with improved antioxidant capacity and enhanced carbo-hydrate metabolism in P.notoginseng.