砷胁迫对三七皂苷和黄酮含量、关键酶活性的影响及其蛋白质组分析

通过田间小区试验,研究不同As浓度(0、20、80、140、200和260 mg·kg^-1)连续2年处理对3年生三七根茎(主根、须根、剪口)和茎叶中皂苷、黄酮和As含量、三七鲨烯合酶、苯丙氨酸解氨酶和查尔酮合酶活性,以及叶片蛋白质组的影响,探讨连续2年砷胁迫对三七主要药效成分影响的酶学和蛋白质组学机制.结果表明: 三七须根中总皂苷含量随砷处理浓度的增加而降低.140 mg·kg^-1As处理下,茎叶和剪口总皂苷大于对照.根茎部三七鲨烯合酶活性较茎叶高.三七各部位黄酮含量均随砷处理浓度的增加而降低.140 mg·kg^-1As处理下,根茎部查尔酮合酶和苯丙氨酸解氨酶活性较茎叶高.茎叶和剪口查尔酮合酶活性低于对照,苯丙氨酸解氨酶的活性高于对照.三七各部位砷含量均随砷处理浓度增加而增加.须根中砷含量大于其他部位.140 mg·kg^-1As处理下,与对照相比,差异表达的蛋白质点达21个.叶片蛋白质组中下调的蛋白质包括磷酸核酮糖激酶、热激蛋白、NAD(P)-结合酶、单脱氢抗坏血酸还原酶和细胞色素b6-f复合物铁硫亚基.上调的蛋白质为CDC27家族蛋白、酸性内切壳多糖酶、共生受体激酶、异黄酮还原酶、DAHP合成酶、蛋白激酶、苹果酸脱氢酶、乙二醛酶和谷氨酰胺合成酶.经过连续2年的砷胁迫, 三七各部位砷含量增加,不仅影响了三七叶片光合作用和能量的合成,还减弱了抗氧化和抗逆能力,诱导了代谢解毒物质的酶表达,导致皂苷和黄酮含量降低.三七对砷的耐受阈值为140 mg·kg^-1.

Effects of As stress on contents of saponin and flavonoid,key enzymes activities of Panax notoginseng and its proteomic analysis

Field plot experiments were conducted to study the effect of two-year consecutive As stress As(V): 0, 20, 80, 140, 200 and 260 mg·kg^-1] on contents of As, saponin and flanovoids, the enzyme activities of phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), and squalene synthase (SS) in main root, fibrous root and rhizome and shoot, and proteome of three-year old Panax notoginseng in Wenshan prefecture, Yunnan Province, China. The results showed that total saponin content of fibrous root decreased with increase in As treatment concentration. Total saponin contents of shoot and rhizome increased with 140 mg·kg^-1 As treatment compared with control. SS activity of rhizome was higher than that of shoot. Flavonoid contents of diffe-rent plant parts decreased with increase in As treatment concentration. With 140 mg·kg^-1 As treatment, activities of PAL and CHS in rhizome were higher than that in shoot. CHS activities in shoot and rhizome were lower, and PAL activities were higher than those of the control. As contents in different plant parts of P. notoginseng increased with increase in As treatment concentration. The highest As content was observed in fibrous root. With 140 mg·kg^-1 As treatment, twenty-one diffe-rential proteins (ratio >2, P<0.05) were identified in the inoculated compared to the control. The down-regulated proteins included phosphoribulokinase, heat shock protein, NAD(P)-binding rossmann-fold superfamily proteinisoform, monodehydroascorbate reductase and cytochrome b6-f complex iron-sulfur subunit. The up-regulated proteins included CDC27 family protein, acidic endochitinase isoform, symbiosis receptor-like kinase precursor, isoflavone reductase-like protein, phospho-2-dehydro-3-deoxyheptonate aldolase, putative protein kinase superfamily protein, malate dehydrogenase, glyoxalase I isoform and glutamine synthetase cytosolic isozyme. In general, with two-year consecutive As stress, As contents in different plant parts of P. notoginseng increased, which not only affected the photosynthesis and energy, but also decreased the antioxidation and resilience, and induced the increased expression of protein involved in detoxication, resulted in decrease in the contents of flavonoid and saponin. The tolerant threshold value of P. notoginseng for As was 140 mg·kg^-1.