二年生三七中黄酮含量对砷胁迫的响应及其酶学机理

Response of flavonoid content in Panax notoginseng to As and its enzymological mechanism

为了向三七[Panax notoginseng(Burk.)F.H.Chen]生产及品质保障提供理论和实践依据,采用大田试验和室内分析相结合的方法,研究不同的砷(As)浓度[As(V):0、20、80、140、200和260 mg kg-1,Na3As O4配制]处理对二年生三七不同部位(主根、须根、剪口)As含量和黄酮含量的影响,探讨三七黄酮代谢关键酶苯丙氨酸解氨酶和查尔酮合酶活性对As胁迫的响应.结果表明:(1)三七黄酮含量与As含量的分布规律一致:须根>剪口>主根.各部位As含量与As处理浓度之间呈显著的正相关(P<0.01).各部位中黄酮含量与As含量、As处理浓度之间显著的负相关性与生长时期有关.(2)除在As处理浓度80-260 mg kg-1时,须根中As含量超过1 mg kg-1外,各部位As含量均符合优质三七As的限量标准(≤2.0 mg kg-1).在开花期和成熟期三七黄酮含量大于生长期,As处理浓度为260 mg kg-1时,三七剪口、主根和须根中黄酮含量比对照分别降低5.30%-11.51%、6.42%-12.93%和4.33%-12.36%.(3)As处理浓度≤200 mg kg-1时,剪口和主根中苯丙氨酸解氨酶和查尔酮合酶的活性没有显著的变化,须根中查尔酮合酶活性提高,苯丙氨酸解氨酶活性降低.在As处理浓度为260 mg kg-1时,三七剪口、主根和须根中苯丙氨酸解氨酶和查尔酮合酶活性显著下降.总之,三七剪口、主根和须根中黄酮的含量对As胁迫的响应与As胁迫浓度、生长时期和部位有关,其中,须根最敏感,三七黄酮含量及其关键酶活性能够在As处理浓度为200 mg kg-1范围内维持一定的抗性.

In order to improve production and guarantee quality ofPanax notoginseng, this paper aimed to study the effects of As stress （As（V）： 0, 20, 80, 140, 200 and 260 mg kg-1） on the phenylalanine ammonia lyase （PAL） and chalcone synthase （CHS） activities and contents of As and flanovoids in the main root, fibrous root and rhizome of two-year old P. notoginseng. Field experiments and lab analysis were conducted in Wenshan Prefecture, Yunnan Province, China. The results showed that： （1） The As and flavonoids contents in P. notoginseng were both as fibrous root 〉 rhizome 〉 main root. Significant positive relationships between the As content and As treatment concentration were observed. Significant negative relationships between flavonoids and As treatment concentration existed in plant growth stages. （2） The As content in different parts ofP. notoginseng met the standard value （〈 1.0 mg kg-1） for good quality P. notoginseng, except for that of fibrous root under As treatment concentration 80 - 260 mg kg-1. Flavonoids contents in different parts at flowering and mature stages were higher than in growing stage. Compared with the control （As 0 mg kg-1 treatment）, flavonoids contents in rhizome, main root and fibrous root were 5.30-11.51%, 6.42-12.93% and 4.33-12.36%, respectively, lower under As 260 mg kg-1 treatment. （3） Under As 0-200 mg kgx treatment, no significant change of PAL and CHS activities in rhizome and main root was observed, with PAL activity decreased and CHS activity increased in fibrous roots. Activities of PAL and CHS in all parts decreased with As 260 mg kg-1 treatment. The results indicated that the responses of flavonoids in rhizome, main root and fibrous root to As stress depend on As concentration, growth stage and plant parts. The fibrous root is the most sensitive part to As stress. Flavonoids contents and activities of key metabolism enzyme are tolerant to As stress of ≤ 200 mg kg-1.