钾素对紫色甘薯花青素合成的影响机制研究

Purple sweet potato is rich in anthocyanin while the fresh tuber yield of purple sweet potato is lower than normal sweet potato. Moreover, anthocyanin content in root changes greatly under different cultivation conditions. Potassium has become the important factors that affect yield and anthocyanin content of purple sweet potato. Potassium could increase anthocyanin content in plant by improving the enzyme activities of phenylalanine ammonialyase, but few studies issued for the key enzyme activity during anthocyanin biosynthesis, anthocyanin accumulation of anthocyanin in root of purple sweet potato by potassium application. In this project, new purple sweet potato varieties “Chuanzishu 1” and “Nanzishu 014”will be used as material for the experiments at different potassium application amount and stages in the pot cultivation, through the adoption of enzyme activity assay method and real-time fluorescent quantitative PCR method, to study the variation of anthocyanin content and accumulation, key enzyme activity and gene expression during anthocyanin synthesis, from the different levels such as anthocyanin content, enzymatic mechanism and activity expression of enzyme gene to reveal the effects of potassium on biosynthesis and accumulation of anthocyanin, explain the relationship among anthocyanin content, enzymatic mechanism and activity expression of enzyme gene.This project would make clear influence mechanism of potassium on anthocyanin biosynthesis of root tuber of purple sweet potato, then elucidate suitable potassium application that enhance anthocyanin content of purple sweet potato. The implementation of the project would afford important theoretical and practice basis of guiding optimum cultivation with high yield and quality for purple sweet potato.

紫色甘薯块根富含花青素，但鲜薯产量较低，且在不同栽培条件下块根花青素含量变化较大。钾素是影响紫色甘薯产量和花青素含量的重要因素，钾可以通过高苯丙氨酸解氨酶等关键酶活性来增加植物花青素含量，但有关钾素对紫色甘薯块根花青素影响的研究较少。本研究以紫色甘薯新品种川紫薯1号和南紫薯014为材料，通过盆栽试验设置不同的钾素供给量和供给时期，采用酶活性测定、实时荧光定量 PCR检测等方法，研究紫色甘薯块根花青素含量和积累量的变化规律、花青素合成关键酶活性的变化规律、不同生育时期花青素合成途径相关基因表达活性差异，从花青素含量、酶学机制、酶基因活性表达等层次阐明钾素对紫色甘薯块根花青素合成与积累的影响，探明花青素含量、酶学机制和酶基因活性表达之间的关系，揭示钾素影响紫色甘薯块根花青素合成的影响机制，明确提高紫色甘薯花青素含量适宜的钾素供给措施，为指导紫色甘薯调优高产栽培提供重要的理论和实践依据。

本研究以两个紫色甘薯新品种为材料，开展了5个不同的钾素供给量和3个供给时期的盆栽试验。.1、钾素供给影响紫色甘薯块根花青素积累规律的作用机理。（1）供给量：供钾促进了紫色甘薯块根中干物质和花青素的积累，两品种不同供钾量处理块根鲜质量、花青素含量、花青素积累量及南紫薯015的块根干质量总体随供钾量的增加呈先升后降的趋势。（2）供给时期：随着供钾时期的推迟，两品种块根鲜质量、干质量、花青素积累量和南紫薯015块根花青素含量总体呈先升后降的趋势，川紫薯2号块根花青素含量总体则呈升高。.2、钾素供给对紫色甘薯块根花青素合成关键酶活性的影响机理。（1）供给量：川紫薯2号平均块根PAL活性随供钾量增加而降低，平均块根CHI和UFGT活性随供钾量的增加先升后降，DFR活性以K120和K150处理较高。南紫薯015平均块根PAL活性以K120处理最高，平均块根CHI活性以K60和K120处理较高，平均块根UFGT活性以K60处理最高。（2）供给时期：川紫薯2号块根PAL活性和UFGT活性以6周供钾处理最高，平均CHI和DFR活性总体呈降低的趋势。南紫薯015块根PLA和DFR活性先升后降，CHI活性总体则降低。（3）块根PAL活性和花青素含量显著正相关。.3、钾素供给对紫色甘薯花青素合成相关基因表达活性的影响机制。（1）供给量：供钾对块根IbCHS基因表达量有降低的趋势。在块根膨大后期，川紫薯2号K120处理块根IbCHI、IbF3H、IbF3'H基因表达量最高，K120和K150处理块根IbDFR和IbMYB基因表达量较高。南紫薯015 K120和K150处理块根IbCHI、IbF3'H基因表达量较高，K60处理块根IbF3H基因表达量最高，K120处理块根IbDFR基因表达量最高，K150处理块根IbANS和IbMYB基因表达量最高。（2）供给时期：在块根膨大后期，川紫薯2号6周供钾处理块根IbCHS和IbDFR基因表达量最高，0周供钾处理块根IbCHI、IbF3H和IbF3'H基因表达量最高，IbANS和IbMYB基因表达量表现为3周>0周>6周。南紫薯015 3周处理7个花青素合成基因表达量均最高。（3）IbCHS、IbCHI、IbF3'H、IbDFR和IbMYB在块根中的表达量和花青素含量均极显著正相关。.研究结果为紫色甘薯调优高产栽培提供了数据支撑。