摘要
为探究叶面喷施碳点(CDs)对低磷胁迫下甘薯幼苗生长发育的影响,发掘CDs调控甘薯根系响应低磷胁迫的关键基因,解析根系代谢产物与关键基因的协同变化,探讨CDs缓解甘薯低磷胁迫的机制,本研究以商薯19和徐薯32为研究对象,设置低磷水平下(0.01 mmol L-1 KH2PO4)叶面喷施超纯水(CK1)、喷施丹参碳点(CDs)和正常磷水平下(1mmolL-1 KH2PO4)喷施超纯水(CK2)3个处理,对不同处理甘薯根系进行转录组和代谢组学分析,同时考查不同处理中甘薯叶、茎和根系生物量和磷含量的变化.结果表明,叶面喷施丹参CDs显著增加了低磷胁迫下甘薯幼苗叶、茎和根系的生物量,提高了根系磷含量,增强了甘薯幼苗的耐低磷性.转录组分析结果显示,磷酸盐吸收和转运基因(PHO1、PHT1-4)、根系构型调控基因(Z4T6、ZFP5、PLT5)和肌醇磷酸盐生物合成基因(VIP2)在缓解甘薯低磷胁迫中发挥着关键作用.代谢组分析结果显示,CDs处理较CK1处理甘薯根系磷酸肌醇的表达量均显著降低.这表明,低磷胁迫下,叶面喷施CDs通过诱导甘薯根系高亲和磷吸收转运系统、优化根系构型等以提高甘薯对磷素的吸收能力,同时通过调整植株体内的磷代谢过程来维持磷稳态.但CDs介导下不同甘薯品种的低磷胁迫反应也存在差异.与CK1处理相比,CDs处理中还观察到商薯19根系磷酸乙醇胺和4-磷酸肌醇等磷酸酯的表达量显著降低;而徐薯32根系分泌的柠檬酸和草酸的表达量显著增加,它们能够活化土壤中的难溶性磷,促进植物磷吸收.这可能与不同甘薯品种本身的耐低磷性存在差异有关.研究结果可为建立甘薯磷养分高效的调控理论与调控新途径提供科学支撑和理论依据,也为后续针对纳米CDs缓解甘薯低磷胁迫的相关研究提供了候选分子资源.
Abstract
The objective of this study is to explore the effects of foliar sprayed carbon dots(CDs)on the growth and development of sweetpotato seedlings under low phosphorus(P)stress,discovery the key genes that regulate the response of sweetpotato roots to low P stress,analyze the synergistic changes between root metabolites and key genes,and explore the mechanism of CDs alle-viating low P stress in sweetpotato.In this study,Shangshu 19 and Xushu 32 were selected as the experimental materials.Three treatments,namely,foliar sprayed with ultra-purewater(CK1 treatment),Salvia miltiorrhiza CDs(CDs treatment)at low P levels(0.01 mmol L-1 KH2PO4),foliar sprayed with ultra-pure water at normal P levels(1 mmol L-1 KH2PO4)(CK2 treatment),were set up to conduct metabolomic and transcriptomic analysis of sweetpotato roots in different treatments,and analysis the changes in biomass and P content in leaves,stems and roots.Results showed that foliar sprayed Salvia miltiorrhiza CDs significantly increased the biomass of leaves,stems,and roots of sweetpotato seedlings under low P stress,increased the P content of roots,and enhanced the low P tolerance of sweetpotato seedlings.Transcriptome analysis revealed that phosphate uptake and transport genes(PHO1,PHTl-4),root configuration regulation genes(ZAT6,ZFP5,PLT5),and inositol phosphate biosynthesis genes(VIP2)play key roles in alleviating low P stress in sweetpotato seedlings.The metabolomic analysis indicated that the relative expression level of inositol phosphate in sweetpotato roots treated with CDs was significantly lower than that in CK1 treatment.These results sug-gested that foliar spraying CDs can improve the ability of sweetpotato to absorb P by inducing the high affinity P uptake and transport system of sweetpotato and optimizing root configuration,while maintaining P homeostasis by adjusting the P metabo-lism process in the plant.However,there were differences in the response of different sweetpotato varieties to low P stress medi-ated by CDs.Compared with CK1 treatment,it was also observed that the expression levels of phosphate esters such as phos-phoethanolamine and D-Myo-inositol 4-phosphate in the roots of Shangshu 19 were significantly reduced in CDs treatment,and the expression of citric acid and oxalic acid secreted by the roots of Xushu 32 significantly increased,which can activate insoluble P in the soil and promote P absorption by plants.This may be related to differences in low P tolerance among different sweetpo-tato varieties.In conclusion,these results can provide scientific support and theoretical basis for establishing efficient regulation theories and new pathways for P nutrition in sweetpotato,and also provide candidate molecular resources for subsequent research on nano CDs to alleviate low P stress in sweetpotato.
维普
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