石灰介导下三七对镉胁迫的根部响应特征及机理研究

Soil Cd contents in Panax notoginseng (Burk) F.H.Chen production areas exceeding the national standard value,which would influence in the security of medical plant P. notoginseng, were reported. P. notoginseng as geoherbs of Yunnan Province would be chosen as research materials. The simulation pot trials would be conducted with theory and methods of pollution ecology and molecular biology. The aims are: (1) to understand biomass, Cd contents, total saponins, singal saponins R1, Rg1 and Rb1, root exudates, root spatial structure, activities of squalene synthase (SS) and its transcription expression, differential expression of proteome in main roots, branching root, fibrous roots and rhizomes of two-year-old and three-year-old P. notoginseng with different soil Cd treatments and lime application; (2) to analysis the responses of roots of P. notoginseng to Cd stress with lime application; and (3) to clarify the protoeme and molecular mechanisms of responses of roots of P. notoginseng to Cd stress with lime application based on differential expression of proteome, activities of squalene synthase and its genes expression. That would be of important and be used for establishment theory and practice roles for guarantee yields and quality of P. notoginseng and promotion industrial development and ecological security of P. notoginseng with lime regulatory.

在土壤镉超标威胁到三七质量安全的背景下，以云南道地药材三七为研究对象，应用污染生态学和分子生物学理论，采用盆栽试验的方法，在不同Cd胁迫条件和石灰处理水平下，研究原产地文山三七二年生和三年生植株主根、支根、须根和剪口中Cd含量、生物量、总皂苷含量、单体皂苷R1、Rg1和Rb1含量、根系分泌物组成与含量、根系空间结构、三七鲨烯合酶的活性和基因的转录表达、根部蛋白质组差异表达；分析石灰介导下三七根部特征对土壤Cd胁迫的响应；探讨石灰介导下三七根系对土壤Cd响应的蛋白质组和分子调控机理。构建在酸性土壤镉污染条件下，保障三七的安全生产及三七产品品质的石灰调控的理论和技术。

土壤镉污染对植物生长和生理的影响及其调控是备受关注的重要科学问题。该项目研究石灰介导下，三七对Cd胁迫的根部响应，探明石灰影响三七皂苷产量镉响应的根系分泌物、酶学及分子机理，具有重要的理论与实践意义。.（1）镉胁迫下施用石灰，显著增加土壤pH值，降低土壤有效镉含量，提高三七株高、叶面积和生物量、根长、根表面积和根体积，显著降低三七镉含量。 .（2）Cd胁迫下，在一定石灰施用范围内，根系分泌的可溶性糖、游离氨基酸柠檬酸、苹果酸、乙酸和草酸含量随石灰施用量的增加而降低。.（3）在高镉胁迫下施用石灰，增加三七R1、Rg1、Rb1和总皂苷产量。镉胁迫下，施加750 kg/hm2石灰，三七开花期和成熟期主根总皂苷含量增加。皂苷合成相关酶DS酶、SE酶、GT酶、P450酶活性都随着石灰的施用量增加而升高。通过iTRAQ分析，鉴定到差异蛋白1181个。在石灰介导镉胁迫下，UDP-糖基转移酶84B1、3-羟基-3-甲基戊二酰辅酶A合成酶、细胞色素P450 CYP376A54和71A1表达上调，对皂苷合成有促进作用。在镉胁迫下，随着石灰施用量的增加，甲羟戊酸激酶(MVK) 酶、P450还原酶、β-香树脂醇合成酶活性和表达显著下降。.（4）Cd胁迫阻碍ABC转运家族蛋白、钙转运ATP酶10、钙相关信号转导蛋白VGCC的表达，增加三七主根与转运相关的ATPase、VGCC和CAXs活性。Ca/Cd比例小于700时，钙的施用能促进P450活性和三醇型皂苷的合成。.阐明了石灰介导下，三七对Cd胁迫的根部响应，探明了石灰影响三七皂苷产量镉响应的根系分泌物、酶学及分子机理，明确了过量施用钙或镉胁迫均会抑制二醇型向三醇型皂苷转化和糖基化过程，改变皂苷单体的异质化，降低皂苷总量，指出了Ca/Cd的相对量是影响含量和相关转运蛋白的重要因素。研究结果有显著的新颖性。